- Email: [email protected]
The effect of surgical handwash routines on the microbial counts operating room nurses
The effect of surgical handwashing routines on the microbial counts of operating room nurses Lesley J. Pereira, RN, BAppSc (Adv. Nurs.) Gary M. Lee, BSc, PhD Ken J. Wade, BSc, DipEd, PhD Camperdown, New South Wales, Australia
Many factors may affect the efficiency of handwashing techniques. This study examined two interdependent factors: the time taken to wash the hands and the type of antiseptic solution used. A 3-minute initial scrub and 30-second consecutive scrub regimen was compared with a current standard regimen of a S-minute initial scrub and a 3-minute consecutive scrub. Chlorhexidine gluconate 4% and povidone-iodine 7.5% were the antiseptics used in the two regimens. The sample (n = 34) was drawn from nurses employed in the operating room suite of a 950-bed hospital. Chlorhexidine gluconate was found to be responsible for lower numbers of colony-forming units of bacteria than povidone-iodine. The duration of the scrub had no significant effect on the numbers of bacteria when povidone-iodine was used. The optimal regimen was found to be the S-minute initial and 3-minute consecutive scrubs with chlorhexidine gluconate. (AM J INFECT CONTROL 1990; l&354-64)
Surgical handwashing (surgical scrubbing) and the wearing of sterile gowns and gloves is an important part of operating room practice. These procedures, however, can not completely eliminate the risk of wound inoculation with microorganisms present on the hands of the surgical team. ‘2* The incidence of glove perforations, for example, has been reported to occur in as many as 24% of operations.3* 4 With this in mind, operating room personnel strive to keep the numbers of microorganisms on the hands at the lowest possible level during surgery to reduce the risk of accidental spillage of microorganisms into an open wound. The prevention of surgical wound infection is a responsibility of operating room personnel. Contamination of wounds from microorFrom the Department Nursing, Cumberland Supported by the New and the Commonwealth
of Biological Sciences and the School College of Health Sciences. South Wales Department
of
Nurses Registration Board of Veterans’ Affairs.
Reprint requests: L. J. Pereira, RN, BAppSc (Adv. Nurs.), The Children’s Hospital, Pyrmont Bridge Rd., Camperdown, Sydney 2050, Australia. 17/46/19666 354
ganisms on the hands of scrub nurses and surgeons is only one possible cause of surgical wound infection. Although an extreme example, the dramatic reductions in maternal mortality achieved by Semmelweis through handwashing highlights the importance of handwashing. Such dramatic instances no longer occur, and with the range of treatments patients undergo, causal relationships become increasingly difficult to infer. It is likely, however, that the risk of surgical wound infection caused by wound inoculation from hand microflora is lessened as reductions in the numbers of colony forming units (CFU) are achieved. For this reason an estimation of the reduction in numbers of CFU on the hands of operating room nurses has been chosen as the measure of efficacy of the scrubbing regimens under consideration. Two factors influencing the efficiency of hand disinfection were examined in this study: the duration of the surgical scrub and the type of antiseptic solution employed. Reducing the duration of surgical handwashing from 10 minutes to 5 minutes has been experimentally justified.6*7 Thus the S-minute sur-
Volume December
16 Number
6
E,fect of surgical
1990
gical scrub has been accepted as the standard method.*-” The possibility of a further reduction in the duration of surgical scrubbing was studied by Murie and Macpherson.‘4 Three minutes’ disinfection with chlorhexidine in methanol was compared with a chlorhexidine gluconate (Hibiscrub) wash for 5 minutes. More recently, Aly and Maibach” found a 2-minute surgical scrub with a chlorhexidine spongebrush to be effective in reducing the natural bacterial flora of gloved hands for a prolonged period. Although not studied directly, Dineen’ and Ayliffe16 recommend even shorter disinfection durations of I minute and 30 seconds, respectively. Antiseptic solutions have been compared in numerous studies. In general, alcohols appear to achieve greater reductions in microorganism numbers than chlorhexidine detergents, which achieve greater reductions than povidone-iodine detergents.16.18 Alcoholic preparations of chlorhexidine, however, appear to be the most effective antiseptic, achieving the greatest immediate reductions in microorganisms and providing the best residual action.14* “* lg Despite their greater antimicrobial efficacy, alcoholic antiseptics are generally banned from Australian operating rooms because of their potential to ignite if used inappropriately. Thus the use of alcoholic antiseptics could not be incorporated into the design of this study. The purpose of this study was to determine whether a shorter duration surgical scrub achieves the same reductions in CFU as a standard scrub.8 The relative effectiveness of two different but commonly used antiseptics for the two time regimens was also examined. METHODS Subject recruitment
and design
A group of operating room suite personnel who do not normally scrub (anesthetic, recovery, and “day only” ward nurses) in a large (950bed) metropolitan teaching hospital was examined. Any person with a known allergy or sensitivity to either of the antiseptics or with an obvious dermatitis of the hands was excluded from the study. Each person taking part in the study partic-
handwashing
routines
355
ipated once in each of the following four treatment groups (conditions): 1. Five-minute initial scrub and 3-minute consecutive scrub with 4% chlorhexidine gluconate (Hibiclens, ICI Australia Operations Pty. Ltd., Sydney) 2. Three-minute initial scrub and 30-second consecutive scrub with 4% chlorhexidine gluconate 3. Five-minute initial scrub and 3-minute consecutive scrub with 7.5% povidoneiodine (Betadine, F. H. Faulding & Co., Ltd., Theberton, S. Africa) 4. Three-minute initial scrub and 30-second consecutive scrub with 7.5% povidoneiodine This protocol constituted a 2 x 2 factorial design with repeated measures over both factors. Thus the two levels of the duration factor were the 5 minutes initial/3 minutes consecutive scrub regimen and the 3 minutes initial/30 seconds consecutive scrub regimen. The two levels of the antiseptic factor were chlorhexidine gluconate and povidone-iodine. Each participant was taught both scrub regimens (described in Tables 1 and 2). Subjects were randomly assigned to one of four groups, and each group was assigned to one of the four scrub regimens each week. Control of the treatment order was achieved through a Latin square design, as described by Wirier.“’ A week of nonscrubbing intervened between each test day, during which time subjects were permitted to continue their normal handwashing practices. Subjects were supervised by the investigator while they scrubbed on all test occasions. Scrubs were performed within the operating room suite, and high filtration masks were worn by all personnel during the scrubbing, gowning, and gloving procedure. Microbiologic
procedures
The Modified Peterson glove rinse sampling procedure, as described by Larson et al.?’ was used. Briefly, the subject wore a sterile surgical glove before each sampling and then 50 ml of phosphate buffer (pH 7.9) containing 1% polysorbate 80 (for neutralization22r 23) was instilled into the glove. The glove was sealed at the wrist with a tourniquet, and the gloved hand was
355
Pereira
American INFECTION
et al.
Table 1. Five-minute surgical scrub procedure Five-minute initial scrub Keep hands hither than elbows for entire procedure. 1. ‘Rinse hands and arms under running water. 2. Pump 2 ml antiseptic solution and wash hands for 30 seconds. Wash arms up to and including 3 cm past elbows with circular motion. 3. Leaving antiseptic on, clean nails well with nail cleaner under running water. 4. Rinse antiseptic off hands and arms. 5. Pump 2 ml antiseptic onto scrub sponge/brush. Scrub nails well with brush. Using sponge side, scrub each hand for 1 minute, paying attention between digits 6. Still using sponge side, scrub up arms in circular motion, finishing 3 cm below elbows. 7. Discard scrub sponge/brush and rinse off antiseptic. a. Pump 2 ml antiseptic and wash hands thoroughly. Wash up arms in circular motion, finishing midforearm. 9. Rinse off antiseptic. 10. Pump 2 ml antiseptic and wash hands thoroughly. 11. Rinse off antiseptic. 12. Dry hands and arms with sterile towel. Three-minute As for initial
consecutive scrub scrub, omitting use of sponge/brush.
Table 2. Three-minute surgical scrub procedure Three-minute initial scrub Keep hands hiaher than elbows for entire procedure 1. Rinse handsand arms under running water. 2. Pump 5 ml antiseptic solution onto scrub sponge/brush. Scrub nails well with brush for 30 seconds on each hand. 3. Discard scrub sponge/brush and rinse off antiseptic. 4. Pump 5 ml antiseptic and spread over wet hands and arms up to and including 3 cm past elbows. Leave on for 1 minute. 5. Develop suds on both hands, then both arms (finishing 3 cm below elbows) for an additional minute. 6. Rinse off antiseptic. 7. Dry hands and arms with sterile towel. Thirty-second Wash hands seconds.
consecutive scrub and arms with antiseptic
solution
for 30
massaged for 1 minute. While the glove was still on the hand, a sample of the fluid was taken. Sample dilutions were cultured according to the method of Miles et a1F4 with the use of trypticase soy agar with lecithin and polysorbate 80
Journal of CONTROL
as the culture media.” Plates were incubated aerobically for 48 hours at 37” C. Samples were collected on four occasions for each condition: (1) immediately before scrubbing (both hands), (2) immediately after the initial surgical scrub (nondominant hand only), (3) 2 hours after the initial surgical scrub, immediately before the consecutive scrub (dominant hand), and (4) 2 hours after one consecutive surgical scrub (dominant hand). Statistical
analysis
The dependent variable was CFU counts, which were transformed to base-10 logarithms (log,,) before analysis.25’ 26 Analyses were performed on the data pertaining to glove rinse specimens collected at the following times: baseline, CFU counts (log,J from specimens collected before scrubbing; time 1, CFU counts (log,,) from specimens collected from the nondominant hand immediately after the initial scrub; time 2, CFU counts (log,,,) from specimens collected 2 hours after the initial scrub was performed and immediately before the consecutive scrub (dominant hand); and time 3, CFU counts (log,,) from specimens collected 2 hours after the consecutive scrub was performed (dominant hand). To analyze for valid differences among the four conditions at times after baseline, the differences existing among the conditions at baseline must be controlled.27 This was achieved by using analysis of covariance (ANCOVA) with the baseline measures as the covariate. When differences among the conditions at time 3 were analyzed, time 2 measures were also used as a covariate. This allowed differences in CFU that existed immediately before the consecutive scrub to be controlled for; thus only the effect of the consecutive scrubs on CFU is considered. In contrast, the time 3 analysis that used the baseline data covariate considered the effect of the combined initial and consecutive scrub regimens. In ANCOVA, finding that the covariate is a significant source of variation simply reflects the strength of correlation of the covariate with the dependent variable.27 ANCOVA determined the existence of any differences among the conditions. To gain more information on the nature of the differences,
Volume 18 Number December 1990
6
specific questions were asked pertaining to the data. This was achieved statistically through the use of special contrasts, by which data not relevant to a question were excluded. The special contrasts used for the analyses of data at the latter three occasions were designed to answer the following questions: 1. Is there a difference between the postscrub CFU counts for the two methods of scrubbing when povidone-iodine antiseptic is used? 2. Is there a difference between the postscrub CFU counts for the two methods of scrubbing when chlorhexidine gluconate antiseptic is used? 3. Does the S-minute initial and 30-second consecutive scrub regimen with chlorhexidine gluconate achieve lower CFU counts than the other three regimens? To demonstrate change over time among the conditions in the CFU count of the dominant hand, ideally the CFU count pertaining to dominant hand specimens under each of the conditions at time 1 should have been measured. Because the values were not directly established, the regression equations of time 1 data on baseline data for the nondominant hand were used to estimate the value at time 1 for the dominant hand.27 By doing this one assumes that the same reductions in CFU occurred on the dominant hand at time 1 as were measured on the nondominant hand. To differentiate the time 1 data for the dominant hand from the measured data of the nondominant hand, these estimated data have been labeled estimated time I. In accordance with previous dependent variable definitions, it is defined as follows: Estimated time ;I: The estimated CFU counts (log,,) of the dominant hand immediately after the initial scrub determined through regression from the nondominant hand data RESULTS
Thirty-six subjects were recruited, but two subjects withdrew from the experiment before completing all four treatments (scrubs) because of skin reactions, including erythema, burning sensations, and local swelling. Descriptive data were collected by questionnaires distributed before participation in the study, for the pur-
Effect of surgical
handwashing
routines
357
3. Means (SD) of baseline microbial counts (loglO)
Table
No. of subjects Nondominant hand Dominant hand
34 34
Mean (SD) 5.4007 5.2151
(0.439) (0.403)
pose of external validity. The subjects who completed all scrubs comprised 6 men and 28 women between the ages of 21 and 55 years. The sample was predominantly white (n = 30). Thirty subjects were right handed and four were left handed. Handwashing frequency was estimated to be between 11 and 25 times per day in the majority of cases (n = 23). Eleven reported their skin to be dry, 21 reported normal skin, and two reported having oily skin. Table 3 details the mean microbial counts and standard deviations (SD) of the dominant and the nondominant hands before scrubbing. A paired sample t test was used to identify any differences at the baseline (before scrubbing) in CFU counts between the dominant and the nondominant hands. The mean log,, CFU count for the nondominant hand was found to be significantly higher than that of the dominant hand (t [33] = 3.88, p < 0.001). Since a significant difference between the dominant and nondominant hands at baseline was found and later analyses were to be based on the dominant hand data, it was necessary to calculate predicted microbial counts for the dominant hand immediately after the initial scrub. The estimated means and SD for the four treatment conditions have been included with the measured means and SD in Table 4. The graphic representation of the measured and predicted means for the dominant hand (Fig. 1) highlights the trends of the four treatment conditions by linking the occasions that samples were collected. Solid lines are used between measured means and broken lines are used to connect estimated means to measured means. The analyses of data at times 1,2, and 3 with the use of the baseline CFU counts as the covariate are summarized in Tables 5, 6, and 7, respectively. Table 8 contains a summary of the time 3 analysis when the time 2 CFU counts were used as the covariate.
American
358
Pereira et al.
INFECTION
Journal
of
CONTROL
6.4
i; -
4.8
z e 4.4 E* c .t: &
4.2
k J
Estimated Time 1 (Immediately following initial scrub)
Time 2
Time
3
Specimen
Fig. 1. Means of CFUs (log,,,): n , Chlorhexidine gluconate, Sminute initial, 3-minute consecutive; 0, chlorhexidine ghCOnate, 3-minute initial, 30-second consecutive; A, povidone-iodine, 5-minute initial, 3-minute consecutive; 0, povidoneiodine, 3-minute initial, 30-second consecutive.
The significant antiseptic main effect seen in each of these tables corresponds to the gap between the two chlorhexidine gluconate conditions and the two povidone-iodine conditions seen in the graph (Fig. 1). By time 3 a gap is also present between the two chlorhexidine gluconate conditions. This gap is the basis for the significant difference indicated in Tables 7 and 8. It is not surprising that all three sources of variation based on the covariate in Table 8 are significant, because there is a strong correlation between the measures at time 2 and those at time 3. As discussed previously, the analysis summarized in Table 8 controls for differences in CFU that existed immediately before the consecutive scrub whereas Table 7 shows the effect of the combined initial and consecutive scrub regimens. These results differ with respect to
the interaction effect (that is, comparing the difference in effect of the antiseptics with the difference in effect of the two scrub durations). A significant interaction effect was evident only when the initial and consecutive scrubs were considered together (Table 7), indicating that a complex relationship exists between antiseptic and duration at this stage. Inspection of the graph of the means (Fig. 1) and the presence of a significant interaction effect prompted the use of special contrasts. Covariate analyses of the three special contrasts at each of the data collection times were performed to make comparisons between selected treatment combinations. No significant difference was found between the two durations of scrubbing with povidoneiodine at any occasion of measurement. A significant difference in CFU counts between the
Volume 18 Number December 1990
6
Effect
surgical handwashing routines
of
359
Table 4. Means (SD) of CFU (IogJ retrieved from hands on each sampling Nondominant Scrub
regimen
Baseline
Chlorhexidine gluconate. 5 min initial/3 min consecutive Chlorhexidine gluconate: 3 min initial/30 set consecutive Povidone-iodine: 5 min initial/3 min consecutive Povidone-iodine: 3 min initial/30 set consecutive
Table 5. Time Source
1
Covariate Duration Error
effect
effect
difference
Time 1
hand
Estimated time 1
Baseline
Time 2
Time 3
5.404
(0.622)
3.997
(0.704)
5.154
(0.562)
3.838
(0.358)
3.606
(0.641)
3.449
(0.813)
5.408
(0.599)
4.182
(0.641)
5.227
(0.568)
4.111
(0.226)
3.833
(0.592)
4.023
(0.628)
5.491
(0.664)
4.333
(0.567)
5.282
(0.549)
4.301
(0.083)
4.356
(0.650)
4.548
(0.482)
5.300
(0.722)
4.313
(0.705)
5.198
(0.622)
4.276
(0.230)
4.239
(0.740)
4.674
(0.537)
Sum8 of squares
Covariate Interaction Error ‘Significant
Dominant
nondominant hand ANCOVA summary (baseline covariate)
of varlatlon
Within cells Covariate Antiseptic Error
hand
Degreea
of freedom
Mean square
F ratlo
Probability
0.72 1.91 8.16
1 1 32
0.72 1.91 0.26
2.81 7.50
0.103 0.010
0.40 0.33 7.31
1 1 32
0.40 0.33 0.23
1.74 1.43
0.196 0.241
1.11 0.18 7.46
1 1 32
1.11 0.18 0.23
4.76 0.76
0.037* 0.388
Mean square
F ratio
of F @)
@ < 0.05)
Table 5. Time 2 ANCOVA summary (baseline covariate) Source
of variation
Within cells Covariate Antiseptic Error Covariate Duration Error
Sum of square8
effect
effect
Covariate Interaction Error ‘Significant
difference
Degrees
of freedom
Probability
0.30 10.67 13.34
1 1 32
0.30 10.67 0.42
0.71 25.59
0.405 0.000
0.42 0.11 8.28
1 1 32
0.42 0.11 0.26
1.63 0.41
0.211 0.525
2.85 0.56 7.48
1 1 32
2.85 0.56 0.23
12.20 2.40
0.001* 0.131
of F @)
@ -z: 0.05).
two durations of scrubbing using chlorhexidine was only evident at time 3 (time 3 [time 2 covariate]: F [1,30] = 6.824, p = 0.014; time 3 [baseline covariate]: F [1,303 = 14.890, at time 2 the F ratio P = 0.001); however, approaches a value that is of interest (F [1,30] = 3.586, p = 0.068). The longer-duration
scrub regimen with chlorhexidine was associated with significantly ductions in CFU than the other mens on all sampling occasions [1,30] = 6.796, p = 0.014; time 2: 24.334, p = 0.000; time 3 [time 2 F [1,30] = 19.104, p = 0.000; time
gluconate greater rethree regi(time 1: F F [1,30] = covariate]: 3 [baseline
360
American Journal of INFECTION CONTROL
Pereira et al.
Table 7. Time 3 ANCOVA Source
of variation
Within cells Covariate Antiseptic
summary
effect
difference
Covariate Duration Error
effect
effect
Covariate Interaction Error ‘Significant
difference
0.012* 0.000’
0.11 4.18 8.87
1 1 32
0.11 4.18 0.28
0.39 15.07
0.535 o.ooo*
1.53 1.23 7.94
1 1
1.53 1.23
6.1 4.98
32
0.25
summary
Sum of squares
of variation
Within cells Covariate Antiseptic Error
2.13 23.65 0.30
7.06 78.57
9.63
1 1 32
of freedom
Probability
of F @)
0.01 a* 0.033*
@ < 0.05).
Table 6. Time 3 ANCOVA Source
F ratio
Degrees
2.13 23.65
effect
Covariate Interaction Error ‘Significant
covariate) Mean square
Sum of squares
Error Covariate Duration Error
(baseline
(time 2 covariate) Degrees
of freedom
Mean square
F ratio
Probability
4.42 27.24
0.044* o.ooo*
1.43 a.79 10.33
1 1 32
1.43 a.79 0.32
2.41 3.46 6.57
1
2.41
11.73
1 32
3.46 0.21
16.87
0.002* o.ooo*
i .a7 0.70 7.60
1 1 32
i .a7 0.70 0.24
7.87 2.95
o.ooa* 0.096
of F @)
(JJ < 0.05).
covariate]: F [1,30] = 53.552, p = 0.000). This can be seen clearly in Fig. 1, where the CFU count for Sminute initial and 3-minute consecutive scrubs with chlorhexidine gluconate is consistently lower than those in the other conditions. Analyses of time 2 and time 3 data were also performed with the estimated time 1 data as the covariate (Tables 9 and 10). These results are purely theoretical, assuming the scrub regimens to have the same effect on CFU for the dominant and nondominant hands. They have been included as an indication of the possible persistent action of the antiseptics. At time 2 (Table 9) no significant differences among the conditions were detected by ANCOVA; however, the special contrasts demonstrated a significant difference between the long- and the short-duration scrub regimens with chlorhexidine gluconate (F [1,30] = 4.873, p = 0.035). The long (S-minute initial and 3-minute con-
secutive) chlorhexidine gluconate scrub was found to be responsible for significantly smaller CFU numbers than those with the other three regimens (F [1,30] = 5.495, p = 0.026). At time 3 (Table 10) significant differences were detected between the two antiseptics irrespective of the duration of the scrub, and between the two scrub methods (durations) irrespective of the type of antiseptic used. The special contrasts demonstrated differences between the two durations of scrub with chlorhexidine gluconate antiseptic (F Cl,301 = 7.241, p = 0.012) and the long chlorhexidine gluconate scrub compared with the other treatments (F Cl,301 = 9.156,~ = 0.005). DISCUSSION The value of scrubbing to prevent surgical wound infection cannot be doubted. Current practice may, however, be somewhat ritualistic. The pursuit of more efficient and effective
Volume December
18 Number
6
1990
methods is of concern to operating room nurses, particularly when such methods save time and money. 2* It is possible that current practice may even be detrimental in that the use of prolonged surgical hand washing methods may traumatize hands unnecessarily. Thus during a period of time they may contribute to surgical sepsis rather than preventing it. Frequent handwashing (more than 25 times per day) may result in an increase in the number of microorganisms found on the hands .13r2g*31 Skin irritation and allergies caused by frequent regular use of antiseptics and traumatic scrub techniques31 prevent staff from performing their duties. Attrition of experienced operating room persotmel presents a problem to management and to patients whose surgery may be cancelled because of staff shortages. In a preliminary survey of scrub nurses in the operating room suite where this experiment was conducted, approximately one third indicated an adverse reaction to at least one of the two antiseptics. Two of 50 nurses could not use either antiseptic and used only soap. Many of the studies show soap to be significantly less effective than antiseptics for immediate reductions in microorganisms.6* I’, *‘. *L 2gf 32-34 Furthermore, soap lacks any persistent or residual effect.6, 17. 32-35 Although this study has not dealt with the related issues of skin condition or the long-term effects of compliance with the four scrub protocols, it does examine the efficacy of the surgical scrub procedure. A feature of this handwashing study is that it was conducted in a clinical setting, and, by considering two factors affecting handwashing efficacy simultaneously, it has demonstrated an interaction between factors. No distinction between pathogens and nonpathogens has been drawn in this study, because some resident skin flora may become pathogenic if introduced into a surgical wound.36 Rather, the overall reduction in the number of transient and resident hand microflora was chosen as the measure of efficacy of the handwashing regimens. This overall reduction has been documented as the aim of the surgical scrub .‘* 37-3g Initially, the four treatments were similar
Effict
of surgical
handwashing
routines
361
with respect to CFU numbers, although chlorhexidine gluconate was responsible for slightly smaller numbers than povidone-iodine. The difference in efficacy of the two antiseptics increased with time, possibly because of a difference in their persistent activity. Although this study was not designed to examine persistent activity as such, correcting for differences immediately after the initial scrub by the use of estimated time 1 data as a covariate, the analyses of times 2 and 3 data (Tables 9 and 10) provide some indication of this. That is, greater reductions in the numbers of CFU after the immediate reductions following the first scrub may be attributed to persistent effect. There is no apparent difference in action of the two antiseptics 2 hours after the initial scrub, although the action of the long scrub with chlorhexidine gluconate was significantly better than the other three regimens. When the regimens consisting of the initial and consecutive scrubs together were considered in relation to the estimated data, all analyses demonstrated significant differences, with the exception of the analysis comparing the short scrub regimen with the standard one for povidone-iodine. This indicates that chlorhexidine gluconate had a better persistent action than povidone-iodine. The longer chlorhexidine gluconate contact time on the second scrub appeared to have a cumulative effect. The longer duration scrub with chlorhexidine gluconate was the only treatment which maintained low numbers of microorganisms after consecutive scrubs. Once again, no significant difference was observed between consecutive scrubs with povidoneiodine, but there was a marked difference when chlorhexidine gluconate was used. Although the longer-duration scrub regimen appears to be better than the shorter one when chlorhexidine gluconate was used, no significant difference was observed between the long- and short-duration scrubs when povidone-iodine was used. This interdependent relationship was reflected in the following way. First, there was a significant difference between the means when grouped by antiseptic type (antiseptic main effect). Second, there was no significant difference between the means when grouped according to the duration of the scrub
362
American Journal of INFECTION CONTROL
Pereira et al.
Table 9. Time 2 ANCOVA summary (estimated time 1 covariate) Source
of variation
Sum of aquareo
Within cells Covariate Antiseptic effect Error Covariate Duration effect Error Covariate Interaction Error ‘Significant
difference
Degrees
1.64 0.18 12.00 0.01 0.05 8.70 2.23 0.00 8.10
of freedom
Mean square
1 1 32 1 1 32 1 1 32
1.64 0.18 0.37 0.01 0.05 0.27 2.23 0.00 0.25
F ratio
Probability
of F @)
4.38 0.48
0.044* 0.492
0.04 0.19
0.840 0.655
8.81 0.02
0.006 0.895
@ < 0.05).
Table 10. Time 3 ANCOVA summary (estimated time 1 covariate) Source
of varlatlon
Sum of squares
Within cells Covariate Antiseptic effect Error Covariate Duration effect Error Covariate Interaction Error “Significant
difference
1.62 1.53 10.13 0.12 2.59 8.85 0.98 0.34 8.49
Dsgrsm
of freedom
1 1 32 1 1 32 1 1
32
Mean square
1.62 1.53 0.32 0.12 2.59 0.28 0.98 0.34 0.27
F ratto
Probability
of F @)
5.12 4.82
0.031” 0.035*
0.45 9.36
0.506 0.004*
3.71 1.29
0.063 0.264
@ < 0.05)
(duration main effect) until time 3. Third, a significant interaction effect (the presence of a difference between the main effects) was noted at time 3. Overall, the long- and shortduration scrubs with chlorhexidine gluconate maintained significantly lower microbial numbers than either of the povidone-iodine regimens. Thus the results indicate that the choice of antiseptic to be used for scrubbing has a greater effect on the overall reductions in microorganisms than the time taken to scrub. In practice, however, allergies and sensitivities of personnel may prevent the use of what would seem to be the more effective antiseptic. Alcohol-based antiseptics, although not commonly used in operating room suites because the risk of ignition, have been suggested to be effective alternatives,14* M-‘~ particularly for shorter-duration handwashing. Unfortunately, alcoholic scrub antiseptics also carry the stigma of being excessively drying to the skin.
This has not been supported by the literature, particularly in view of the fact that many commercially available formulations contain emollients .40 This study has considered specific formulations of two commonly used antiseptics. Although the activity of some types of antiseptics varies according to the specific formulations,40 new light has been shed on the surgical scrub procedure. Further study with a greater variety of antiseptics of varying formulations is warranted. Although the shorter-duration scrub examined here does not achieve maximal reduction in microorganisms, it is as effective as currently used regimens. The adoption of a shorter scrub holds many potential advantages, including savings in time and money. Possibly, a less traumatic scrub with reduced contact time of antiseptics will prevent or retard the development of allergies and sensitivities to antiseptics by
Volume December
18 Number
8
Effect of surgical handwashing routines
1990
operating room personnel. At the least, operating room personnel may be expected to experience less drying and cracking of the skin of the hands, which would not only be pleasing to the staff themselves but may also promote lower baseline microbial counts. In conclusion, although the shorter-duration surgical scrub is apparently adequate with either of the scrub antiseptics tested, the longerduration surgical scrub with chlorhexidine gluconate achieves and maintains the best microbial reductions. The advantages of a shorter scrub, such as savings in time, money, and reduced trauma to skin, may, however, encourage the adoption of the shorter regimen by operating room personnel. The four scrub regimens described in this study are now being investigated to determine the effects of their prolonged use on the skin condition of the hands of operating room nursing personnel. We gratefully acknowledge the operating room nursing staff of Westmead Hospital, Sydney, for their support and cooperation. Some materials and equipment were kindly provided by Indoplas Pty. Ltd., Sydney; Disposable Products Pty. Ltd., Adelaide; ICI Australia Operations Pty. Ltd.; and Westmead Hospital Building Maintenance and Audiovisual Services Departments. Support in the form of discounts was received from Laboratory Equipment Pty. Ltd., Sydney, and Becton Dickinson Pty. Ltd., Sydney.
11.
12.
13. 14.
15.
16. 17 I,.
18. 19.
20. 21.
22.
References 1. Lowbury EJL, Lilly HA. Disinfection of the hands of surgeons and nurses. Br Med J 1960; 1445-50. 2. Mitchell AAB, Pettigrew JB, Timbury MC, Hutchison JGP. An epidemic of postoperative wound infection by type-80 staphylococci. Lancet 1959;2:503-5. 3. Devenish EA, Miles AA. Control of SfaphyZococ~~~ aureus in an operating-theatre. Lancet 1939;l: 1088-94. 4. Walter CW, Kudsin RB. The bacteriologic study of surgical gloves from 250 operations. Surg Gynaecol Gbstet 1969;129:949-52. 5. Rotter ML. Hygienic hand disinfection. Infect Control 1984;5:18-22. 6. Dineen P. An evaluation of the duration of the surgical scrub. Surg Gynaecol Obstet 1969;129:1181-5. 7. Tucci VJ, Stone AM, Thompson C, Isenberg HD, Wise L. Studies of the surgical scrub. Surg Gynaecol Obstet 1977;145:415-6. 8. Australian Confederation of Operating Room Nurses. ACORN guidelines and recommended practices. 9. AORN Recommended Practices Subcommittee. Proposed recommended practices for surgical scrubs. AORN J 1983;37:82. 10. Berry AR, Watt B, Goldacre MJ, Thomson JWW, McNair TJ. A comparison of the use of povidone-iodine
23.
24. 25.
363
and chlorhexidine in the prophylaxis of postoperative wound infection. J Hosp Infect 1982;3:55-63. Hall R. Povidone-iodine and chlorhexidine gluconate containing detergents for disinfection of the hands. J Hosp Infect 1980;1:367-8. Garner JS, ed. Guideline for Prevention of Surgical Wound Infections, 1985. (CDC guideline PB85-923403) Atlanta: U.S. Department of Health and Human Services, 1985:B. Larson E. Current handwashing issues. Infect Control 1984;5:15-7. Murie JA, Macpherson SG. Chlorhexidine in methanol for the preoperative cleansing of surgeons’ hands: a clinical trial. Scott Med J 1980;25:309-11. Aly R, Maibach HI. Comparative antibacterial efficacy of a 2-minute surgical scrub with chlorhexidine gluconate, povidone-iodine, and chloroxylenol spongebrushes. AM J INFECT CONTROL 1988;16:173-7. Ayliffe GAJ. Surgical scrub and skin disinfection. Infect Control 1984;5:23-7. Rotter ML. Povidone-iodine and chlorhexidine gluconate containing detergents for disinfection of hands. J Hosp Infect 1981;2:273-6. Sebben JE. Surgical antiseptics. J Am Acad Dermatol 1983;9:759-65. Aly R, Maibach HI. A comparison of the antimicrobial effect of 0.5% chlorhexidine (Hibistat) and 70% isopropyl alcohol on hands contaminated with Serratia marcescens. Clin Exp Dermatol 1980;5:197-201. Winer BJ. Statistical principles in experimental design. 2nd ed. Tokyo: McGraw-Hill Kogakusha, 1962:685-91. Larson E, Leyden JJ, McGinley KJ, Grove GL, Talbot GH. Physiologic and microbiologic changes in the skin related to frequent handwashing. Infect Control 1986; 7:59-63. Larson EL, Strom MS, Evans CA. Analysis of three variables in sampling solutions used to assay bacteria of hands: type of solution, use of antiseptic neutralizers, and solution temperature. J Clin Microbial 1980; Sept:355-60. Russell AD. Neutralization procedures in the evaluation of bactericidal activity. In: Collins CH, Allwood MC, Bloomfield SF, Fox A, eds. Disinfectants: their use and evaluation of effectiveness. London: Academic Press, 1981:45-59. Miles AA, Misra SA, Irwin JO. The estimation of the bactericidal power of the blood. J Hyg (Land) 1938; 38:733. Hall R, Denton G, Bucknall RA. Use and evaluation of antiseptics for the treatment of intact and broken skin (wounds) in hospital. In: Collins CH, Allwood MC, Bloomfield SF, Fox A, eds. Disinfectants: their use and evaluation of effectiveness. London: Academic Press, 1981:112.
26. LaRccca PT, LaRocca MAK. Surgical scrubs. Infect Control 1987;8:230. 27. Huck SW, Cormier WI-I, Bounds WG. Reading statistics and research. New York: Harper & Row, 1974:103-47, 151-6. 28. Brown TR, Ehrlich CE, Stehman FB, Golichowski AM; Madura JA, Eitzen HE. A clinical evaluation of chlorhexidine gluconate spray as compared with iodophor
364
29.
30. 31.
32.
33.
34.
American INFECTION
Pereira et al.
scrub for preoperative skin preparation. Surg Gynaecol Obstet 1984;158:363-366. Larson E. Effects of handwashing agent, handwashing frequency, and clinical area on hand flora. AM J INFECT CONTROL 1984;12:76-82. Larson E. Handwashing and skin physiologic and bacteriologic aspects. Infect Control 1985;6:14-23. Mitchell KG, Rawluk DJR. Skin reactions related to surgical scrub-up: results of a Scottish survey. Br J Surg 1984;71:223-4. Ayliffe GAJ, Babb JR, Davies JG, Lilly HA. Hand disinfection: a comparison of various agents in laboratory and ward studies. J Hosp Infect 1988; 11:226-243. Larson E, Mayur K, Laughon BA. Influence of two handwashing frequencies on reduction in colonizing flora with three handwashing products used by health care personnel. AM J INFECT CONTROL 1989; 17:83-g. Ojajarvi J. Effectiveness of hand washing and disinfection methods in removing transient bacteria after patient nursing. J Hyg (Camb) 1980;35:193-203.
Bound
volumes
available
35.
36.
37. 38.
39. 40.
Journal of CONTROL
Bartzokas CA, Gibson MF, Graham R, Pinder DC. A comparison of triclosan and chlorhexidine preparations with 60 percent isopropyl alcohol for hygienic hand disinfection. J Hosp Infect 1983;4:245-55. Price PB. The bacteriology of normal skin; a new quantitative test applied to a study of bacterial flora and the disinfectant action of mechanical cleaning. J Infect Dis 1938;63:301-18. Ayliffe GAJ. The effect of antibacterial agents on the flora of the skin. J Hosp Infect 1980; 1: 11 l-24. Newsom SWB, Matthews J. Studies on the use of povidone-iodine with the ‘hygienic hand disinfection’ test. J Hosp Infect 1985;6(suppl):45-50. Reybrouck G. Handwashing and hand disinfection. J Hosp Infect 1986;8:5-23. Larson E. Final guideline for use of topical antimicrobial agents. AM J INFECT CONTROL 1988;16:254-66.
to subscribers
Bound volumes of AMERICAN JOURNAL OF INFECTION CONTROL are available to subscribers (only) for the 1990 issues from the Publisher, at a cost of $19.00 ($25.00 international) for Vol. 18 (January-December). Shipping charges are included. Each bound volume contains a subject and an author index. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Drive, St. Louis, Missouri 63146-3318, USA; phone 800-325-4177, ext. 4351. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular Journal subscription.
Many factors may affect the efficiency of handwashing techniques. This study examined two interdependent factors: the time taken to wash the hands and the type of antiseptic solution used. A 3-minute initial scrub and 30-second consecutive scrub regimen was compared with a current standard regimen of a S-minute initial scrub and a 3-minute consecutive scrub. Chlorhexidine gluconate 4% and povidone-iodine 7.5% were the antiseptics used in the two regimens. The sample (n = 34) was drawn from nurses employed in the operating room suite of a 950-bed hospital. Chlorhexidine gluconate was found to be responsible for lower numbers of colony-forming units of bacteria than povidone-iodine. The duration of the scrub had no significant effect on the numbers of bacteria when povidone-iodine was used. The optimal regimen was found to be the S-minute initial and 3-minute consecutive scrubs with chlorhexidine gluconate. (AM J INFECT CONTROL 1990; l&354-64)
Surgical handwashing (surgical scrubbing) and the wearing of sterile gowns and gloves is an important part of operating room practice. These procedures, however, can not completely eliminate the risk of wound inoculation with microorganisms present on the hands of the surgical team. ‘2* The incidence of glove perforations, for example, has been reported to occur in as many as 24% of operations.3* 4 With this in mind, operating room personnel strive to keep the numbers of microorganisms on the hands at the lowest possible level during surgery to reduce the risk of accidental spillage of microorganisms into an open wound. The prevention of surgical wound infection is a responsibility of operating room personnel. Contamination of wounds from microorFrom the Department Nursing, Cumberland Supported by the New and the Commonwealth
of Biological Sciences and the School College of Health Sciences. South Wales Department
of
Nurses Registration Board of Veterans’ Affairs.
Reprint requests: L. J. Pereira, RN, BAppSc (Adv. Nurs.), The Children’s Hospital, Pyrmont Bridge Rd., Camperdown, Sydney 2050, Australia. 17/46/19666 354
ganisms on the hands of scrub nurses and surgeons is only one possible cause of surgical wound infection. Although an extreme example, the dramatic reductions in maternal mortality achieved by Semmelweis through handwashing highlights the importance of handwashing. Such dramatic instances no longer occur, and with the range of treatments patients undergo, causal relationships become increasingly difficult to infer. It is likely, however, that the risk of surgical wound infection caused by wound inoculation from hand microflora is lessened as reductions in the numbers of colony forming units (CFU) are achieved. For this reason an estimation of the reduction in numbers of CFU on the hands of operating room nurses has been chosen as the measure of efficacy of the scrubbing regimens under consideration. Two factors influencing the efficiency of hand disinfection were examined in this study: the duration of the surgical scrub and the type of antiseptic solution employed. Reducing the duration of surgical handwashing from 10 minutes to 5 minutes has been experimentally justified.6*7 Thus the S-minute sur-
Volume December
16 Number
6
E,fect of surgical
1990
gical scrub has been accepted as the standard method.*-” The possibility of a further reduction in the duration of surgical scrubbing was studied by Murie and Macpherson.‘4 Three minutes’ disinfection with chlorhexidine in methanol was compared with a chlorhexidine gluconate (Hibiscrub) wash for 5 minutes. More recently, Aly and Maibach” found a 2-minute surgical scrub with a chlorhexidine spongebrush to be effective in reducing the natural bacterial flora of gloved hands for a prolonged period. Although not studied directly, Dineen’ and Ayliffe16 recommend even shorter disinfection durations of I minute and 30 seconds, respectively. Antiseptic solutions have been compared in numerous studies. In general, alcohols appear to achieve greater reductions in microorganism numbers than chlorhexidine detergents, which achieve greater reductions than povidone-iodine detergents.16.18 Alcoholic preparations of chlorhexidine, however, appear to be the most effective antiseptic, achieving the greatest immediate reductions in microorganisms and providing the best residual action.14* “* lg Despite their greater antimicrobial efficacy, alcoholic antiseptics are generally banned from Australian operating rooms because of their potential to ignite if used inappropriately. Thus the use of alcoholic antiseptics could not be incorporated into the design of this study. The purpose of this study was to determine whether a shorter duration surgical scrub achieves the same reductions in CFU as a standard scrub.8 The relative effectiveness of two different but commonly used antiseptics for the two time regimens was also examined. METHODS Subject recruitment
and design
A group of operating room suite personnel who do not normally scrub (anesthetic, recovery, and “day only” ward nurses) in a large (950bed) metropolitan teaching hospital was examined. Any person with a known allergy or sensitivity to either of the antiseptics or with an obvious dermatitis of the hands was excluded from the study. Each person taking part in the study partic-
handwashing
routines
355
ipated once in each of the following four treatment groups (conditions): 1. Five-minute initial scrub and 3-minute consecutive scrub with 4% chlorhexidine gluconate (Hibiclens, ICI Australia Operations Pty. Ltd., Sydney) 2. Three-minute initial scrub and 30-second consecutive scrub with 4% chlorhexidine gluconate 3. Five-minute initial scrub and 3-minute consecutive scrub with 7.5% povidoneiodine (Betadine, F. H. Faulding & Co., Ltd., Theberton, S. Africa) 4. Three-minute initial scrub and 30-second consecutive scrub with 7.5% povidoneiodine This protocol constituted a 2 x 2 factorial design with repeated measures over both factors. Thus the two levels of the duration factor were the 5 minutes initial/3 minutes consecutive scrub regimen and the 3 minutes initial/30 seconds consecutive scrub regimen. The two levels of the antiseptic factor were chlorhexidine gluconate and povidone-iodine. Each participant was taught both scrub regimens (described in Tables 1 and 2). Subjects were randomly assigned to one of four groups, and each group was assigned to one of the four scrub regimens each week. Control of the treatment order was achieved through a Latin square design, as described by Wirier.“’ A week of nonscrubbing intervened between each test day, during which time subjects were permitted to continue their normal handwashing practices. Subjects were supervised by the investigator while they scrubbed on all test occasions. Scrubs were performed within the operating room suite, and high filtration masks were worn by all personnel during the scrubbing, gowning, and gloving procedure. Microbiologic
procedures
The Modified Peterson glove rinse sampling procedure, as described by Larson et al.?’ was used. Briefly, the subject wore a sterile surgical glove before each sampling and then 50 ml of phosphate buffer (pH 7.9) containing 1% polysorbate 80 (for neutralization22r 23) was instilled into the glove. The glove was sealed at the wrist with a tourniquet, and the gloved hand was
355
Pereira
American INFECTION
et al.
Table 1. Five-minute surgical scrub procedure Five-minute initial scrub Keep hands hither than elbows for entire procedure. 1. ‘Rinse hands and arms under running water. 2. Pump 2 ml antiseptic solution and wash hands for 30 seconds. Wash arms up to and including 3 cm past elbows with circular motion. 3. Leaving antiseptic on, clean nails well with nail cleaner under running water. 4. Rinse antiseptic off hands and arms. 5. Pump 2 ml antiseptic onto scrub sponge/brush. Scrub nails well with brush. Using sponge side, scrub each hand for 1 minute, paying attention between digits 6. Still using sponge side, scrub up arms in circular motion, finishing 3 cm below elbows. 7. Discard scrub sponge/brush and rinse off antiseptic. a. Pump 2 ml antiseptic and wash hands thoroughly. Wash up arms in circular motion, finishing midforearm. 9. Rinse off antiseptic. 10. Pump 2 ml antiseptic and wash hands thoroughly. 11. Rinse off antiseptic. 12. Dry hands and arms with sterile towel. Three-minute As for initial
consecutive scrub scrub, omitting use of sponge/brush.
Table 2. Three-minute surgical scrub procedure Three-minute initial scrub Keep hands hiaher than elbows for entire procedure 1. Rinse handsand arms under running water. 2. Pump 5 ml antiseptic solution onto scrub sponge/brush. Scrub nails well with brush for 30 seconds on each hand. 3. Discard scrub sponge/brush and rinse off antiseptic. 4. Pump 5 ml antiseptic and spread over wet hands and arms up to and including 3 cm past elbows. Leave on for 1 minute. 5. Develop suds on both hands, then both arms (finishing 3 cm below elbows) for an additional minute. 6. Rinse off antiseptic. 7. Dry hands and arms with sterile towel. Thirty-second Wash hands seconds.
consecutive scrub and arms with antiseptic
solution
for 30
massaged for 1 minute. While the glove was still on the hand, a sample of the fluid was taken. Sample dilutions were cultured according to the method of Miles et a1F4 with the use of trypticase soy agar with lecithin and polysorbate 80
Journal of CONTROL
as the culture media.” Plates were incubated aerobically for 48 hours at 37” C. Samples were collected on four occasions for each condition: (1) immediately before scrubbing (both hands), (2) immediately after the initial surgical scrub (nondominant hand only), (3) 2 hours after the initial surgical scrub, immediately before the consecutive scrub (dominant hand), and (4) 2 hours after one consecutive surgical scrub (dominant hand). Statistical
analysis
The dependent variable was CFU counts, which were transformed to base-10 logarithms (log,,) before analysis.25’ 26 Analyses were performed on the data pertaining to glove rinse specimens collected at the following times: baseline, CFU counts (log,J from specimens collected before scrubbing; time 1, CFU counts (log,,) from specimens collected from the nondominant hand immediately after the initial scrub; time 2, CFU counts (log,,,) from specimens collected 2 hours after the initial scrub was performed and immediately before the consecutive scrub (dominant hand); and time 3, CFU counts (log,,) from specimens collected 2 hours after the consecutive scrub was performed (dominant hand). To analyze for valid differences among the four conditions at times after baseline, the differences existing among the conditions at baseline must be controlled.27 This was achieved by using analysis of covariance (ANCOVA) with the baseline measures as the covariate. When differences among the conditions at time 3 were analyzed, time 2 measures were also used as a covariate. This allowed differences in CFU that existed immediately before the consecutive scrub to be controlled for; thus only the effect of the consecutive scrubs on CFU is considered. In contrast, the time 3 analysis that used the baseline data covariate considered the effect of the combined initial and consecutive scrub regimens. In ANCOVA, finding that the covariate is a significant source of variation simply reflects the strength of correlation of the covariate with the dependent variable.27 ANCOVA determined the existence of any differences among the conditions. To gain more information on the nature of the differences,
Volume 18 Number December 1990
6
specific questions were asked pertaining to the data. This was achieved statistically through the use of special contrasts, by which data not relevant to a question were excluded. The special contrasts used for the analyses of data at the latter three occasions were designed to answer the following questions: 1. Is there a difference between the postscrub CFU counts for the two methods of scrubbing when povidone-iodine antiseptic is used? 2. Is there a difference between the postscrub CFU counts for the two methods of scrubbing when chlorhexidine gluconate antiseptic is used? 3. Does the S-minute initial and 30-second consecutive scrub regimen with chlorhexidine gluconate achieve lower CFU counts than the other three regimens? To demonstrate change over time among the conditions in the CFU count of the dominant hand, ideally the CFU count pertaining to dominant hand specimens under each of the conditions at time 1 should have been measured. Because the values were not directly established, the regression equations of time 1 data on baseline data for the nondominant hand were used to estimate the value at time 1 for the dominant hand.27 By doing this one assumes that the same reductions in CFU occurred on the dominant hand at time 1 as were measured on the nondominant hand. To differentiate the time 1 data for the dominant hand from the measured data of the nondominant hand, these estimated data have been labeled estimated time I. In accordance with previous dependent variable definitions, it is defined as follows: Estimated time ;I: The estimated CFU counts (log,,) of the dominant hand immediately after the initial scrub determined through regression from the nondominant hand data RESULTS
Thirty-six subjects were recruited, but two subjects withdrew from the experiment before completing all four treatments (scrubs) because of skin reactions, including erythema, burning sensations, and local swelling. Descriptive data were collected by questionnaires distributed before participation in the study, for the pur-
Effect of surgical
handwashing
routines
357
3. Means (SD) of baseline microbial counts (loglO)
Table
No. of subjects Nondominant hand Dominant hand
34 34
Mean (SD) 5.4007 5.2151
(0.439) (0.403)
pose of external validity. The subjects who completed all scrubs comprised 6 men and 28 women between the ages of 21 and 55 years. The sample was predominantly white (n = 30). Thirty subjects were right handed and four were left handed. Handwashing frequency was estimated to be between 11 and 25 times per day in the majority of cases (n = 23). Eleven reported their skin to be dry, 21 reported normal skin, and two reported having oily skin. Table 3 details the mean microbial counts and standard deviations (SD) of the dominant and the nondominant hands before scrubbing. A paired sample t test was used to identify any differences at the baseline (before scrubbing) in CFU counts between the dominant and the nondominant hands. The mean log,, CFU count for the nondominant hand was found to be significantly higher than that of the dominant hand (t [33] = 3.88, p < 0.001). Since a significant difference between the dominant and nondominant hands at baseline was found and later analyses were to be based on the dominant hand data, it was necessary to calculate predicted microbial counts for the dominant hand immediately after the initial scrub. The estimated means and SD for the four treatment conditions have been included with the measured means and SD in Table 4. The graphic representation of the measured and predicted means for the dominant hand (Fig. 1) highlights the trends of the four treatment conditions by linking the occasions that samples were collected. Solid lines are used between measured means and broken lines are used to connect estimated means to measured means. The analyses of data at times 1,2, and 3 with the use of the baseline CFU counts as the covariate are summarized in Tables 5, 6, and 7, respectively. Table 8 contains a summary of the time 3 analysis when the time 2 CFU counts were used as the covariate.
American
358
Pereira et al.
INFECTION
Journal
of
CONTROL
6.4
i; -
4.8
z e 4.4 E* c .t: &
4.2
k J
Estimated Time 1 (Immediately following initial scrub)
Time 2
Time
3
Specimen
Fig. 1. Means of CFUs (log,,,): n , Chlorhexidine gluconate, Sminute initial, 3-minute consecutive; 0, chlorhexidine ghCOnate, 3-minute initial, 30-second consecutive; A, povidone-iodine, 5-minute initial, 3-minute consecutive; 0, povidoneiodine, 3-minute initial, 30-second consecutive.
The significant antiseptic main effect seen in each of these tables corresponds to the gap between the two chlorhexidine gluconate conditions and the two povidone-iodine conditions seen in the graph (Fig. 1). By time 3 a gap is also present between the two chlorhexidine gluconate conditions. This gap is the basis for the significant difference indicated in Tables 7 and 8. It is not surprising that all three sources of variation based on the covariate in Table 8 are significant, because there is a strong correlation between the measures at time 2 and those at time 3. As discussed previously, the analysis summarized in Table 8 controls for differences in CFU that existed immediately before the consecutive scrub whereas Table 7 shows the effect of the combined initial and consecutive scrub regimens. These results differ with respect to
the interaction effect (that is, comparing the difference in effect of the antiseptics with the difference in effect of the two scrub durations). A significant interaction effect was evident only when the initial and consecutive scrubs were considered together (Table 7), indicating that a complex relationship exists between antiseptic and duration at this stage. Inspection of the graph of the means (Fig. 1) and the presence of a significant interaction effect prompted the use of special contrasts. Covariate analyses of the three special contrasts at each of the data collection times were performed to make comparisons between selected treatment combinations. No significant difference was found between the two durations of scrubbing with povidoneiodine at any occasion of measurement. A significant difference in CFU counts between the
Volume 18 Number December 1990
6
Effect
surgical handwashing routines
of
359
Table 4. Means (SD) of CFU (IogJ retrieved from hands on each sampling Nondominant Scrub
regimen
Baseline
Chlorhexidine gluconate. 5 min initial/3 min consecutive Chlorhexidine gluconate: 3 min initial/30 set consecutive Povidone-iodine: 5 min initial/3 min consecutive Povidone-iodine: 3 min initial/30 set consecutive
Table 5. Time Source
1
Covariate Duration Error
effect
effect
difference
Time 1
hand
Estimated time 1
Baseline
Time 2
Time 3
5.404
(0.622)
3.997
(0.704)
5.154
(0.562)
3.838
(0.358)
3.606
(0.641)
3.449
(0.813)
5.408
(0.599)
4.182
(0.641)
5.227
(0.568)
4.111
(0.226)
3.833
(0.592)
4.023
(0.628)
5.491
(0.664)
4.333
(0.567)
5.282
(0.549)
4.301
(0.083)
4.356
(0.650)
4.548
(0.482)
5.300
(0.722)
4.313
(0.705)
5.198
(0.622)
4.276
(0.230)
4.239
(0.740)
4.674
(0.537)
Sum8 of squares
Covariate Interaction Error ‘Significant
Dominant
nondominant hand ANCOVA summary (baseline covariate)
of varlatlon
Within cells Covariate Antiseptic Error
hand
Degreea
of freedom
Mean square
F ratlo
Probability
0.72 1.91 8.16
1 1 32
0.72 1.91 0.26
2.81 7.50
0.103 0.010
0.40 0.33 7.31
1 1 32
0.40 0.33 0.23
1.74 1.43
0.196 0.241
1.11 0.18 7.46
1 1 32
1.11 0.18 0.23
4.76 0.76
0.037* 0.388
Mean square
F ratio
of F @)
@ < 0.05)
Table 5. Time 2 ANCOVA summary (baseline covariate) Source
of variation
Within cells Covariate Antiseptic Error Covariate Duration Error
Sum of square8
effect
effect
Covariate Interaction Error ‘Significant
difference
Degrees
of freedom
Probability
0.30 10.67 13.34
1 1 32
0.30 10.67 0.42
0.71 25.59
0.405 0.000
0.42 0.11 8.28
1 1 32
0.42 0.11 0.26
1.63 0.41
0.211 0.525
2.85 0.56 7.48
1 1 32
2.85 0.56 0.23
12.20 2.40
0.001* 0.131
of F @)
@ -z: 0.05).
two durations of scrubbing using chlorhexidine was only evident at time 3 (time 3 [time 2 covariate]: F [1,30] = 6.824, p = 0.014; time 3 [baseline covariate]: F [1,303 = 14.890, at time 2 the F ratio P = 0.001); however, approaches a value that is of interest (F [1,30] = 3.586, p = 0.068). The longer-duration
scrub regimen with chlorhexidine was associated with significantly ductions in CFU than the other mens on all sampling occasions [1,30] = 6.796, p = 0.014; time 2: 24.334, p = 0.000; time 3 [time 2 F [1,30] = 19.104, p = 0.000; time
gluconate greater rethree regi(time 1: F F [1,30] = covariate]: 3 [baseline
360
American Journal of INFECTION CONTROL
Pereira et al.
Table 7. Time 3 ANCOVA Source
of variation
Within cells Covariate Antiseptic
summary
effect
difference
Covariate Duration Error
effect
effect
Covariate Interaction Error ‘Significant
difference
0.012* 0.000’
0.11 4.18 8.87
1 1 32
0.11 4.18 0.28
0.39 15.07
0.535 o.ooo*
1.53 1.23 7.94
1 1
1.53 1.23
6.1 4.98
32
0.25
summary
Sum of squares
of variation
Within cells Covariate Antiseptic Error
2.13 23.65 0.30
7.06 78.57
9.63
1 1 32
of freedom
Probability
of F @)
0.01 a* 0.033*
@ < 0.05).
Table 6. Time 3 ANCOVA Source
F ratio
Degrees
2.13 23.65
effect
Covariate Interaction Error ‘Significant
covariate) Mean square
Sum of squares
Error Covariate Duration Error
(baseline
(time 2 covariate) Degrees
of freedom
Mean square
F ratio
Probability
4.42 27.24
0.044* o.ooo*
1.43 a.79 10.33
1 1 32
1.43 a.79 0.32
2.41 3.46 6.57
1
2.41
11.73
1 32
3.46 0.21
16.87
0.002* o.ooo*
i .a7 0.70 7.60
1 1 32
i .a7 0.70 0.24
7.87 2.95
o.ooa* 0.096
of F @)
(JJ < 0.05).
covariate]: F [1,30] = 53.552, p = 0.000). This can be seen clearly in Fig. 1, where the CFU count for Sminute initial and 3-minute consecutive scrubs with chlorhexidine gluconate is consistently lower than those in the other conditions. Analyses of time 2 and time 3 data were also performed with the estimated time 1 data as the covariate (Tables 9 and 10). These results are purely theoretical, assuming the scrub regimens to have the same effect on CFU for the dominant and nondominant hands. They have been included as an indication of the possible persistent action of the antiseptics. At time 2 (Table 9) no significant differences among the conditions were detected by ANCOVA; however, the special contrasts demonstrated a significant difference between the long- and the short-duration scrub regimens with chlorhexidine gluconate (F [1,30] = 4.873, p = 0.035). The long (S-minute initial and 3-minute con-
secutive) chlorhexidine gluconate scrub was found to be responsible for significantly smaller CFU numbers than those with the other three regimens (F [1,30] = 5.495, p = 0.026). At time 3 (Table 10) significant differences were detected between the two antiseptics irrespective of the duration of the scrub, and between the two scrub methods (durations) irrespective of the type of antiseptic used. The special contrasts demonstrated differences between the two durations of scrub with chlorhexidine gluconate antiseptic (F Cl,301 = 7.241, p = 0.012) and the long chlorhexidine gluconate scrub compared with the other treatments (F Cl,301 = 9.156,~ = 0.005). DISCUSSION The value of scrubbing to prevent surgical wound infection cannot be doubted. Current practice may, however, be somewhat ritualistic. The pursuit of more efficient and effective
Volume December
18 Number
6
1990
methods is of concern to operating room nurses, particularly when such methods save time and money. 2* It is possible that current practice may even be detrimental in that the use of prolonged surgical hand washing methods may traumatize hands unnecessarily. Thus during a period of time they may contribute to surgical sepsis rather than preventing it. Frequent handwashing (more than 25 times per day) may result in an increase in the number of microorganisms found on the hands .13r2g*31 Skin irritation and allergies caused by frequent regular use of antiseptics and traumatic scrub techniques31 prevent staff from performing their duties. Attrition of experienced operating room persotmel presents a problem to management and to patients whose surgery may be cancelled because of staff shortages. In a preliminary survey of scrub nurses in the operating room suite where this experiment was conducted, approximately one third indicated an adverse reaction to at least one of the two antiseptics. Two of 50 nurses could not use either antiseptic and used only soap. Many of the studies show soap to be significantly less effective than antiseptics for immediate reductions in microorganisms.6* I’, *‘. *L 2gf 32-34 Furthermore, soap lacks any persistent or residual effect.6, 17. 32-35 Although this study has not dealt with the related issues of skin condition or the long-term effects of compliance with the four scrub protocols, it does examine the efficacy of the surgical scrub procedure. A feature of this handwashing study is that it was conducted in a clinical setting, and, by considering two factors affecting handwashing efficacy simultaneously, it has demonstrated an interaction between factors. No distinction between pathogens and nonpathogens has been drawn in this study, because some resident skin flora may become pathogenic if introduced into a surgical wound.36 Rather, the overall reduction in the number of transient and resident hand microflora was chosen as the measure of efficacy of the handwashing regimens. This overall reduction has been documented as the aim of the surgical scrub .‘* 37-3g Initially, the four treatments were similar
Effict
of surgical
handwashing
routines
361
with respect to CFU numbers, although chlorhexidine gluconate was responsible for slightly smaller numbers than povidone-iodine. The difference in efficacy of the two antiseptics increased with time, possibly because of a difference in their persistent activity. Although this study was not designed to examine persistent activity as such, correcting for differences immediately after the initial scrub by the use of estimated time 1 data as a covariate, the analyses of times 2 and 3 data (Tables 9 and 10) provide some indication of this. That is, greater reductions in the numbers of CFU after the immediate reductions following the first scrub may be attributed to persistent effect. There is no apparent difference in action of the two antiseptics 2 hours after the initial scrub, although the action of the long scrub with chlorhexidine gluconate was significantly better than the other three regimens. When the regimens consisting of the initial and consecutive scrubs together were considered in relation to the estimated data, all analyses demonstrated significant differences, with the exception of the analysis comparing the short scrub regimen with the standard one for povidone-iodine. This indicates that chlorhexidine gluconate had a better persistent action than povidone-iodine. The longer chlorhexidine gluconate contact time on the second scrub appeared to have a cumulative effect. The longer duration scrub with chlorhexidine gluconate was the only treatment which maintained low numbers of microorganisms after consecutive scrubs. Once again, no significant difference was observed between consecutive scrubs with povidoneiodine, but there was a marked difference when chlorhexidine gluconate was used. Although the longer-duration scrub regimen appears to be better than the shorter one when chlorhexidine gluconate was used, no significant difference was observed between the long- and short-duration scrubs when povidone-iodine was used. This interdependent relationship was reflected in the following way. First, there was a significant difference between the means when grouped by antiseptic type (antiseptic main effect). Second, there was no significant difference between the means when grouped according to the duration of the scrub
362
American Journal of INFECTION CONTROL
Pereira et al.
Table 9. Time 2 ANCOVA summary (estimated time 1 covariate) Source
of variation
Sum of aquareo
Within cells Covariate Antiseptic effect Error Covariate Duration effect Error Covariate Interaction Error ‘Significant
difference
Degrees
1.64 0.18 12.00 0.01 0.05 8.70 2.23 0.00 8.10
of freedom
Mean square
1 1 32 1 1 32 1 1 32
1.64 0.18 0.37 0.01 0.05 0.27 2.23 0.00 0.25
F ratio
Probability
of F @)
4.38 0.48
0.044* 0.492
0.04 0.19
0.840 0.655
8.81 0.02
0.006 0.895
@ < 0.05).
Table 10. Time 3 ANCOVA summary (estimated time 1 covariate) Source
of varlatlon
Sum of squares
Within cells Covariate Antiseptic effect Error Covariate Duration effect Error Covariate Interaction Error “Significant
difference
1.62 1.53 10.13 0.12 2.59 8.85 0.98 0.34 8.49
Dsgrsm
of freedom
1 1 32 1 1 32 1 1
32
Mean square
1.62 1.53 0.32 0.12 2.59 0.28 0.98 0.34 0.27
F ratto
Probability
of F @)
5.12 4.82
0.031” 0.035*
0.45 9.36
0.506 0.004*
3.71 1.29
0.063 0.264
@ < 0.05)
(duration main effect) until time 3. Third, a significant interaction effect (the presence of a difference between the main effects) was noted at time 3. Overall, the long- and shortduration scrubs with chlorhexidine gluconate maintained significantly lower microbial numbers than either of the povidone-iodine regimens. Thus the results indicate that the choice of antiseptic to be used for scrubbing has a greater effect on the overall reductions in microorganisms than the time taken to scrub. In practice, however, allergies and sensitivities of personnel may prevent the use of what would seem to be the more effective antiseptic. Alcohol-based antiseptics, although not commonly used in operating room suites because the risk of ignition, have been suggested to be effective alternatives,14* M-‘~ particularly for shorter-duration handwashing. Unfortunately, alcoholic scrub antiseptics also carry the stigma of being excessively drying to the skin.
This has not been supported by the literature, particularly in view of the fact that many commercially available formulations contain emollients .40 This study has considered specific formulations of two commonly used antiseptics. Although the activity of some types of antiseptics varies according to the specific formulations,40 new light has been shed on the surgical scrub procedure. Further study with a greater variety of antiseptics of varying formulations is warranted. Although the shorter-duration scrub examined here does not achieve maximal reduction in microorganisms, it is as effective as currently used regimens. The adoption of a shorter scrub holds many potential advantages, including savings in time and money. Possibly, a less traumatic scrub with reduced contact time of antiseptics will prevent or retard the development of allergies and sensitivities to antiseptics by
Volume December
18 Number
8
Effect of surgical handwashing routines
1990
operating room personnel. At the least, operating room personnel may be expected to experience less drying and cracking of the skin of the hands, which would not only be pleasing to the staff themselves but may also promote lower baseline microbial counts. In conclusion, although the shorter-duration surgical scrub is apparently adequate with either of the scrub antiseptics tested, the longerduration surgical scrub with chlorhexidine gluconate achieves and maintains the best microbial reductions. The advantages of a shorter scrub, such as savings in time, money, and reduced trauma to skin, may, however, encourage the adoption of the shorter regimen by operating room personnel. The four scrub regimens described in this study are now being investigated to determine the effects of their prolonged use on the skin condition of the hands of operating room nursing personnel. We gratefully acknowledge the operating room nursing staff of Westmead Hospital, Sydney, for their support and cooperation. Some materials and equipment were kindly provided by Indoplas Pty. Ltd., Sydney; Disposable Products Pty. Ltd., Adelaide; ICI Australia Operations Pty. Ltd.; and Westmead Hospital Building Maintenance and Audiovisual Services Departments. Support in the form of discounts was received from Laboratory Equipment Pty. Ltd., Sydney, and Becton Dickinson Pty. Ltd., Sydney.
11.
12.
13. 14.
15.
16. 17 I,.
18. 19.
20. 21.
22.
References 1. Lowbury EJL, Lilly HA. Disinfection of the hands of surgeons and nurses. Br Med J 1960; 1445-50. 2. Mitchell AAB, Pettigrew JB, Timbury MC, Hutchison JGP. An epidemic of postoperative wound infection by type-80 staphylococci. Lancet 1959;2:503-5. 3. Devenish EA, Miles AA. Control of SfaphyZococ~~~ aureus in an operating-theatre. Lancet 1939;l: 1088-94. 4. Walter CW, Kudsin RB. The bacteriologic study of surgical gloves from 250 operations. Surg Gynaecol Gbstet 1969;129:949-52. 5. Rotter ML. Hygienic hand disinfection. Infect Control 1984;5:18-22. 6. Dineen P. An evaluation of the duration of the surgical scrub. Surg Gynaecol Obstet 1969;129:1181-5. 7. Tucci VJ, Stone AM, Thompson C, Isenberg HD, Wise L. Studies of the surgical scrub. Surg Gynaecol Obstet 1977;145:415-6. 8. Australian Confederation of Operating Room Nurses. ACORN guidelines and recommended practices. 9. AORN Recommended Practices Subcommittee. Proposed recommended practices for surgical scrubs. AORN J 1983;37:82. 10. Berry AR, Watt B, Goldacre MJ, Thomson JWW, McNair TJ. A comparison of the use of povidone-iodine
23.
24. 25.
363
and chlorhexidine in the prophylaxis of postoperative wound infection. J Hosp Infect 1982;3:55-63. Hall R. Povidone-iodine and chlorhexidine gluconate containing detergents for disinfection of the hands. J Hosp Infect 1980;1:367-8. Garner JS, ed. Guideline for Prevention of Surgical Wound Infections, 1985. (CDC guideline PB85-923403) Atlanta: U.S. Department of Health and Human Services, 1985:B. Larson E. Current handwashing issues. Infect Control 1984;5:15-7. Murie JA, Macpherson SG. Chlorhexidine in methanol for the preoperative cleansing of surgeons’ hands: a clinical trial. Scott Med J 1980;25:309-11. Aly R, Maibach HI. Comparative antibacterial efficacy of a 2-minute surgical scrub with chlorhexidine gluconate, povidone-iodine, and chloroxylenol spongebrushes. AM J INFECT CONTROL 1988;16:173-7. Ayliffe GAJ. Surgical scrub and skin disinfection. Infect Control 1984;5:23-7. Rotter ML. Povidone-iodine and chlorhexidine gluconate containing detergents for disinfection of hands. J Hosp Infect 1981;2:273-6. Sebben JE. Surgical antiseptics. J Am Acad Dermatol 1983;9:759-65. Aly R, Maibach HI. A comparison of the antimicrobial effect of 0.5% chlorhexidine (Hibistat) and 70% isopropyl alcohol on hands contaminated with Serratia marcescens. Clin Exp Dermatol 1980;5:197-201. Winer BJ. Statistical principles in experimental design. 2nd ed. Tokyo: McGraw-Hill Kogakusha, 1962:685-91. Larson E, Leyden JJ, McGinley KJ, Grove GL, Talbot GH. Physiologic and microbiologic changes in the skin related to frequent handwashing. Infect Control 1986; 7:59-63. Larson EL, Strom MS, Evans CA. Analysis of three variables in sampling solutions used to assay bacteria of hands: type of solution, use of antiseptic neutralizers, and solution temperature. J Clin Microbial 1980; Sept:355-60. Russell AD. Neutralization procedures in the evaluation of bactericidal activity. In: Collins CH, Allwood MC, Bloomfield SF, Fox A, eds. Disinfectants: their use and evaluation of effectiveness. London: Academic Press, 1981:45-59. Miles AA, Misra SA, Irwin JO. The estimation of the bactericidal power of the blood. J Hyg (Land) 1938; 38:733. Hall R, Denton G, Bucknall RA. Use and evaluation of antiseptics for the treatment of intact and broken skin (wounds) in hospital. In: Collins CH, Allwood MC, Bloomfield SF, Fox A, eds. Disinfectants: their use and evaluation of effectiveness. London: Academic Press, 1981:112.
26. LaRccca PT, LaRocca MAK. Surgical scrubs. Infect Control 1987;8:230. 27. Huck SW, Cormier WI-I, Bounds WG. Reading statistics and research. New York: Harper & Row, 1974:103-47, 151-6. 28. Brown TR, Ehrlich CE, Stehman FB, Golichowski AM; Madura JA, Eitzen HE. A clinical evaluation of chlorhexidine gluconate spray as compared with iodophor
364
29.
30. 31.
32.
33.
34.
American INFECTION
Pereira et al.
scrub for preoperative skin preparation. Surg Gynaecol Obstet 1984;158:363-366. Larson E. Effects of handwashing agent, handwashing frequency, and clinical area on hand flora. AM J INFECT CONTROL 1984;12:76-82. Larson E. Handwashing and skin physiologic and bacteriologic aspects. Infect Control 1985;6:14-23. Mitchell KG, Rawluk DJR. Skin reactions related to surgical scrub-up: results of a Scottish survey. Br J Surg 1984;71:223-4. Ayliffe GAJ, Babb JR, Davies JG, Lilly HA. Hand disinfection: a comparison of various agents in laboratory and ward studies. J Hosp Infect 1988; 11:226-243. Larson E, Mayur K, Laughon BA. Influence of two handwashing frequencies on reduction in colonizing flora with three handwashing products used by health care personnel. AM J INFECT CONTROL 1989; 17:83-g. Ojajarvi J. Effectiveness of hand washing and disinfection methods in removing transient bacteria after patient nursing. J Hyg (Camb) 1980;35:193-203.
Bound
volumes
available
35.
36.
37. 38.
39. 40.
Journal of CONTROL
Bartzokas CA, Gibson MF, Graham R, Pinder DC. A comparison of triclosan and chlorhexidine preparations with 60 percent isopropyl alcohol for hygienic hand disinfection. J Hosp Infect 1983;4:245-55. Price PB. The bacteriology of normal skin; a new quantitative test applied to a study of bacterial flora and the disinfectant action of mechanical cleaning. J Infect Dis 1938;63:301-18. Ayliffe GAJ. The effect of antibacterial agents on the flora of the skin. J Hosp Infect 1980; 1: 11 l-24. Newsom SWB, Matthews J. Studies on the use of povidone-iodine with the ‘hygienic hand disinfection’ test. J Hosp Infect 1985;6(suppl):45-50. Reybrouck G. Handwashing and hand disinfection. J Hosp Infect 1986;8:5-23. Larson E. Final guideline for use of topical antimicrobial agents. AM J INFECT CONTROL 1988;16:254-66.
to subscribers
Bound volumes of AMERICAN JOURNAL OF INFECTION CONTROL are available to subscribers (only) for the 1990 issues from the Publisher, at a cost of $19.00 ($25.00 international) for Vol. 18 (January-December). Shipping charges are included. Each bound volume contains a subject and an author index. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Drive, St. Louis, Missouri 63146-3318, USA; phone 800-325-4177, ext. 4351. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular Journal subscription.