Chlorhexidine Bathing to Reduce Central Venous Catheter-associated Bloodstream Infection: Impact and Sustainability

CLINICAL RESEARCH STUDY

Chlorhexidine Bathing to Reduce Central Venous Catheterassociated Bloodstream Infection: Impact and Sustainability Marisa A. Montecalvo, MD,a,b Donna McKenna, MS,a,b Robert Yarrish, MD,c Lynda Mack, MSN,a George Maguire, MD,d Janet Haas, DNSc,a,b Lawrence DeLorenzo, MD,d Norine Dellarocco, MSN,e Barbara Savatteri, RN,f Addie Rosenthal, MS,g Anita Watson, RN,h Debra Spicehandler, MD,g Qiuhu Shi, PhD,i Paul Visintainer, PhD,j Gary P. Wormser, MD,b a

Infection Prevention and Control Department, Westchester Medical Center, Valhalla, New York; bDivision of Infectious Diseases, Department of Medicine, New York Medical College, Valhalla, New York; cDepartment of Medicine, Sound Shore Medical Center, New Rochelle, New York; d Pulmonary and Critical Care Medicine, Department of Medicine, New York Medical College, Valhalla, New York; eInfection Control, Sound Shore Medical Center, New Rochelle, New York; fHudson Valley Hospital Center, Cortlandt Manor, New York; gMount Vernon Hospital, Mt Vernon, New York; hPhelps Memorial Hospital Center, Sleepy Hollow, New York; iNew York Medical College School of Health Sciences and Practice, Valhalla, New York; jBaystate Medical Center, Springfield, Mass.

ABSTRACT BACKGROUND: Chlorhexidine bathing has been associated with reductions in healthcare-associated bloodstream infection. To determine the impact and sustainability of the effect of chlorhexidine bathing on central venous catheter-associated bloodstream infection, we performed a prospective, 3-phase, multiple-hospital study. METHODS: In the medical intensive care unit and the respiratory care unit of a tertiary care hospital and the medical-surgical intensive care units of 4 community hospitals, rates of central venous catheter-associated bloodstream infection were collected prospectively for each period. Pre-intervention (phase 1) patients were bathed with soap and water or nonmedicated bathing cloths; active intervention (phase 2) patients were bathed with 2% chlorhexidine gluconate cloths with the number of baths administered and skin tolerability assessed; post-intervention (phase 3) chlorhexidine bathing was continued but without oversight by research personnel. Central venous catheterassociated bloodstream infection rates were compared over study periods using Poisson regression. RESULTS: Compared with pre-intervention, during active intervention there were significantly fewer central venous catheter-associated bloodstream infections (6.4/1000 central venous catheter days vs 2.6/1000 central venous catheter days, relative risk, 0.42; 95% confidence interval, 0.25-0.68; P ⬍ .001), and this reduction was sustained during post-intervention (2.9/1000 central venous catheter days; relative risk, 0.46; 95% confidence interval, 0.30-0.70; P ⬍ .001). During the active intervention period, compliance with chlorhexidine bathing was 82%. Few adverse events were observed. CONCLUSION: In this multiple-hospital study, chlorhexidine bathing was associated with significant reductions in central venous catheter-associated bloodstream infection, and these reductions were sustained post-intervention when chlorhexidine bathing was unmonitored. Chlorhexidine bathing was well tolerated and is a useful adjunct to reduce central venous catheter-associated bloodstream infection. © 2012 Published by Elsevier Inc. • The American Journal of Medicine (2012) 125, 505-511 KEYWORDS: Central venous catheter-associated bloodstream infection; Chlorhexidine bathing; Healthcare-associated bloodstream infection.

Reduction of healthcare-associated infections is a top priority for hospitals. In intensive care units, infection is com-

mon and associated with significant morbidity and mortality.1 Healthcare-associated infections are often device-

Presented in part at: the Society for Health Care Epidemiology of America 5th Decennial International Conference on Healthcare-Associated Infections, 2010, Atlanta, Georgia. Funding: New York State Department of Health Hospital-Acquired Infection Reporting Program. Interpretations of data do not necessarily represent interpretation or policy of the New York State Department of Health. Chlorhexidine cloths were provided by Sage Products Inc, Cary, Ill.

Conflict of Interest: None. Authorship: All authors had access to the data and played a role in writing this manuscript. Reprint requests should be addressed to: Marisa A. Montecalvo, MD, Infection Prevention and Control, Macy Pavilion 2095, Westchester Medical Center, Valhalla, NY 10595. E-mail address: [email protected].

0002-9343/$ -see front matter © 2012 Published by Elsevier Inc. doi:10.1016/j.amjmed.2011.10.032

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associated and can be caused by antibiotic-resistant pathogens that in Westchester County, New York. The study units were the flourish in the hospital environment. Preventing healthcare-assomedical intensive care unit of the tertiary care hospital, ciated infections requires rigorous infection control efforts that are which houses oncology and critically ill medical patients usually focused on the healthcare provider.2 A complementary but does not include trauma/surgical patients; the respirainfection control measure is to reduce the number of patients tory care unit of the tertiary care hospital, which houses colonized with a hospital pathogen medical and surgical patients rethrough decolonization strategies. quiring ongoing mechanical ventiThis is known as “source control,” but lation or respiratory care; and CLINICAL SIGNIFICANCE its use has been limited by few availmedical-surgical intensive care able modalities. units of the 4 community hospi● This 3-phase (pre-intervention, interBathing patients with the antiseptals, each of which houses a varivention [chlorhexidine bathing], posttic chlorhexidine is a potential tool for ety of critically ill medical and intervention), multiple-hospital study source control. The mechanism of ansurgical patients. found a statistically significant reductibacterial action involves attachment The study end point was hospition in central venous catheter-associof the positively charged chlorhexital-acquired central venous catheated bloodstream infection during chlordine to the negatively charged bacteter-associated bloodstream infechexidine bathing, and the reduction rial cell causing leakage of cytoplasm, tion rates. The inclusion criterion was sustained during the post-intervenresulting in bactericidal or bacteriofor chlorhexidine bathing was adtion period. static activity. Chlorhexidine reduces mission to the study unit. Excluboth resident and transient skin flora sion criteria were pregnancy, ● Chlorhexidine bathing was well tolewith a residual effect that lasts at least breast feeding, chlorhexidine alrated. 6 hours.3,4 lergy, and severely denuded skin. 5 ● Chlorhexidine bathing seems to be a usedemonstrated that The study was approved with a Vernon et al cleansing medical intensive care unit waiver for written informed conful adjunctive measure for reducing cenpatients with 2% chlorhexidine-satusent by the New York Medical tral venous catheter-associated bloodrated cloths resulted in significantly College Committee for Protection stream infection. fewer colonies of vancomycin-resisof Human Subjects and by the intant enterococci on patients’ skin and stitutional review board of each significantly less contamination of the hospital. environment and healthcare workers’ hands. The incidence of Phase 1 (pre-intervention) started April 1, 2008, at all acquisition of vancomycin-resistant enterococci was reduced by hospitals and lasted for 6 to 9 months on each unit; the 60%.5 Subsequently, studies of chlorhexidine bathing in the same different time intervals allowed units to transition to phase 2 separately. During phase 1, patients were bathed accordunit and in another medical intensive care unit found that the ing to hospital protocol; nonmedicated bathing cloths were period of chlorhexidine bathing was associated with significant 6 used at sites A, B, and E, and soap and water in a basin bath reductions in primary bloodstream infections and central venous 7 were used at sites C, D, and F. catheter-associated bloodstream infections. By using an alterna8 Phase 2 (active intervention) began immediately after tive method to the chlorhexidine saturated cloths, Climo et al evaluated the effect of adding 4% liquid chlorhexidine to paphase 1 and lasted for 8 months on each unit. During phase tients’ bath water. In that multiple-hospital study, there were 2, bathing was performed with 2% chlorhexidine gluconate significantly fewer vancomycin-resistant enterococcal bloodcloths (Sage Products Inc, Cary, Ill) provided to the hospital stream infections and fewer patients acquired vancomycinat no charge. The bathing protocol was to use 1 package of resistant enterococci and methicillin-resistant Staphylococcus 6 cloths with 1 cloth for each of the following anatomic aureus during the period of chlorhexidine bathing. areas: the neck/shoulders and chest, both arms and hands, To extend our understanding of the efficacy of chlorhexiabdomen/groin/perineum, right leg/foot, left leg/foot, and dine bathing, we performed a prospective, 3-phase, multiback and buttocks. If needed, more than 1 package was ple-hospital study designed to evaluate the effect of chloused. The face was cleansed with nonmedicated cloths. rhexidine bathing on central venous catheter-associated During the week before chlorhexidine bathing began, all bloodstream infection and the sustainability of any effect nursing staff received in-service education on bathing prodetected. In addition, skin tolerability and frequency of cedures, study requirements to record the chlorhexidine bathing were assessed during the active intervention period. baths administered on a research flow sheet, and how to assess skin tolerability (at each shift) in consultation with research personnel. Research personnel made rounds on all MATERIALS AND METHODS study units at least weekly. Study Design, End Points, and Setting Phase 3 (post-intervention) began immediately after The study was a prospective, 3-phase study performed from phase 2 and lasted for 12 months on each unit. During phase April 1, 2008, to August 31, 2010. This study was per3 hospitals could continue chlorhexidine bathing, but the formed at 1 tertiary care hospital and 4 community hospitals product was no longer supplied by the study. All 6 units

Montecalvo et al Table 1

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Study Unit Characteristics During the Pre-Intervention, Active Intervention, and Post-Intervention Periods Average Length of Stay in Days*

Unit

Unit No. of Beds

Unit Type

Pre-Intervention

Active Intervention

Post-Intervention

A B C D E F

7, 11† 20 12 5 10 12

Medical intensive care Respiratory care Medical surgical intensive Medical surgical intensive Medical surgical intensive Medical surgical intensive

6.1 16.6 4.4 4.7 4.9 7.3

6.4 16.8 5.2 5.7 5.4 8.0

6.0 11.2 4.9 4.6 7.3 6.9

care care care care

*Derived from the number of patient days divided by the number of admissions. †On the first day of the active intervention period, the unit moved from a 7-bed unit to an 11-bed unit.

chose to continue chlorhexidine bathing using the same product and bathing protocol. Research personnel kept track of whether chlorhexidine bathing was in use, but the baths administered were no longer recorded on research forms. Research personnel continued to be available for any questions regarding skin tolerability. Throughout all phases of the study, the Infection Prevention and Control Department at each site had policies and procedures in the intensive care unit that emphasized the importance of insertion checklists9 to reduce central venous catheter-associated bloodstream infection. During the pre-intervention period of the study, site C began using an antibiotic impregnated central venous catheter 5 months before chlorhexidine bathing began, and site D began using a chlorhexidine-impregnated central venous catheter dressing 3 months before chlorhexidine bathing began.

Definitions All positive blood cultures were reviewed by infection prevention and control staff at each site and classified as central venous catheter-associated bloodstream infection and as hospital-acquired using the National Healthcare Safety Network of the Centers for Disease Control and Prevention definition.10 A central venous catheter-associated bloodstream infection was defined as a patient with a central venous catheter in place with a recognized pathogen cultured from one or more blood cultures AND the organism was not related to an infection at another site; or a common skin organism was cultured from 2 or more blood cultures drawn on separate occasions (within 2 days of each other) AND at least 1 of the following signs or symptoms was present: fever (⬎38°C), chills, or hypotension, AND the signs and symptoms and positive blood cultures were not due to infection at another site. Central venous catheterassociated bloodstream infection was defined as acquired on the study unit if the signs and symptoms of infection were not incubating at the time of admission and the positive blood culture was drawn while the patient was housed on the unit or within 48 hours of the time of discharge from the unit. The denominator for the central venous catheter-associated bloodstream infection rates was 1000 central venous

catheter days. Days eligible for a bath included the day of admission to the unit, the day of discharge from the unit, and all days hospitalized on the unit.

Statistical Methods The sample size estimate was derived from a known rate of 4 healthcare-associated bacteremias per 1000 patient days at the tertiary care medical center during the year before the study began. On the basis of published studies, it was assumed that chlorhexidine bathing would result in a 50% reduction of healthcare-associated bloodstream infection.6 To achieve a statistically significant reduction (P ⫽ .05) in central venous catheter-associated bloodstream infection with a power of 80%, the sample size estimate was 12,700 patient days each for the pre-intervention period and 12,700 patient days for the active intervention period. Infection rates were modeled over the 3 study periods using Poisson regression.11 In this approach, total infection counts are adjusted for total central venous catheter days, stratified by hospital and study period. Both hospital and study period were modeled using indicator variables. Results are expressed as adjusted incidence rate ratios with accompanying 95% confidence intervals (CIs). Pairwise comparison of rates over study periods was conducted using the Wald test with Bonferroni’s adjustment to the P value. We conducted a subanalysis that excluded the 2 sites (C and D) that had initiated parallel interventions that may have influenced study results. The subanalyses were conducted as described above. Analyses were conducted using Stata version 11.1 (StataCorp, College Station, Tex) and SAS version 9.1 (SAS Institute Inc, Cary, NC). A critical test level of 5% was considered statistically significant, unless adjusted for multiple comparisons.

RESULTS The study unit characteristics, number of beds, and average length of stay during each period of the study are shown in Table 1. The number of patient days and the number of admissions for each study phase was 12,603 patient days, 1808 admissions for the pre-intervention period; 13,864 patient days, 1832 admissions for the active intervention period; and 19,914 patient days and 2834 admissions for the

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Table 2 Rates of Central Venous Catheter-associated Bloodstream Infection During the Pre-Intervention, Active Intervention, and Post-Intervention Periods Active Intervention Chlorhexidine Bathing

Post-Intervention* Chlorhexidine Bathing

Central Venous Catheter Days Rate†

No. of Central Venous Catheter-associated Bloodstream Infections

Central Venous Catheter Days Rate

No. of Central Venous Catheter-associated Bloodstream Infections

Central Venous Catheter Days Rate

940 1688 717 205 1063 655 5268

9 14 0 0 2 0 25

1772 2022 646 397 943 686 6466

14 18 2 3 2 0 39

2892 2755 909 299 1457 976 9288

Pre-Intervention

Site

No. of Central Venous Catheter-associated Bloodstream Infections

A 6 B 25 C 6 D 2 E 4 F 3 Total 46 Adjusted rate‡

6.4 14.8 8.4 9.8 3.8 4.6 8.7 6.4

5.1 6.9 0.0 0.0 2.1 0.0 3.9 2.6

4.8 6.5 2.2 10.0 1.4 0 4.2 2.9

*Post-intervention all sites continued chlorhexidine bathing; sites E and F had periods of bathing without chlorhexidine of 4 and 5 months, respectively. †Rate ⫽ number of central venous catheter-associated bloodstream infections per 1000 central venous catheter days. ‡The central venous catheter-associated bloodstream infection rate is adjusted for total central venous catheter days, stratified by hospital and study period.

days; relative risk [RR], 0.42, 95% CI, 0.25-0.68; P ⬍ .001) (Table 2). This reduction was sustained during the postintervention period (2.9/1000 central venous catheter days; RR, 0.46; 95% CI, 0.30-0.70; P ⬍ .001) (Figure 1). There was little difference in the rates of central venous catheterassociated bloodstream infection between the active intervention period and the post-intervention period (P ⫽ .9). During the lapse in chlorhexidine bath supply at sites E and F during the post-intervention period, 1 site had 2 infections (Table 2). These numbers were considered too small to reassess the chlorhexidine effect. A subanalysis was performed excluding sites C and D, which had begun using other products that may reduce central venous catheter-

Central venous catheter-associated bloodstream infec
on rate per 1000 central venous catheter days

post-intervention period. On the first day of the active intervention period, site A moved the intensive care unit from a 7-bed unit to a new 11-bed unit. Exclusions from chlorhexidine bathing occurred for 2 patients during the active intervention period, 1 due to pregnancy and 1 due to StevensJohnson syndrome. Chlorhexidine bathing was discontinued in 3 patients because of skin rash and restarted in 2 of the 3 patients without adverse event; the third patient also had thrombocytopenia that resolved with the discontinuation of multiple medications and chlorhexidine. During the active intervention period, chlorhexidine baths were given on 12,196 (82%) of 14,942 days that patients were eligible for a bath. A total of 18,357 chlorhexidine baths were given, indicating an average of 1.5 chlorhexidine baths daily. The reasons recorded for not administering a chlorhexidine bath included the patient being admitted to or discharged from the unit that day (54% of missed baths) or unknown (46% of missed baths). During the post-intervention period, chlorhexidine baths were in use by study units for 17,519 (88%) of 19,914 post-intervention study days. Two units, E and F, did not use chlorhexidine for bathing for 4 and 5 months, respectively, because of lapses in product supply at the beginning of the post-intervention period when chlorhexidine baths were no longer provided by the study. Rates of central venous catheter-associated bloodstream infection, unadjusted and adjusted for study center, are shown in Table 2. Compared with the pre-intervention period adjusted rate (6.4/1000 central venous catheter days), there was a significant reduction in the rate of central venous catheter-associated bloodstream infection during the active intervention period (2.6/1000 central venous catheter

10 9 8 7 6 5 4 3 2 1 0 Pre-intervention

Active Intervention

Post-intervention

Figure 1 Adjusted rates of central venous catheter-associated bloodstream infection with limits of the 95% CI range for each point estimate.

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Table 3 Microorganisms Isolated in Blood Cultures from Patients with Central Venous Catheter-associated Bloodstream Infection During the Pre-Intervention and Active Intervention Periods of the Study Central Venous Catheter-associated Bloodstream Infection

Microorganism

Pre-Intervention

Active Intervention Chlorhexidine Bathing

Gram-positive bacteria Coagulase negative Staphylococci Staphylococcus aureus (No. ⫽ methicillin resistant) Enterococcus spp. (No. ⫽ vancomycin-resistant) Streptococcus viridians Gram-negative bacteria Klebsiella spp. (No. ⫽ extended spectrum beta-lactamase producer or resistant to multiple antibiotics) Acinetobacter spp. Enterobacter spp., Escherichia coli, Proteus spp. Pseudomonas spp. Candida spp. Infections with ⬎ 1 microorganism isolated

21 7 3 (3) 10 (5) 1 21 14 (6)

15 2 4 (1) 9 (6) 0 6 5 (2)

associated bloodstream infection during the pre-intervention period. By excluding sites C and D, compared with the pre-intervention rate (2.5/1000 central venous catheter days), there was still a significant reduction in the rate of central venous catheter-associated bloodstream infection during the active intervention period (1.3/1000 central venous catheter days; RR, 0.54; 95% CI, 0.33-0.90; P ⫽ .02), and this reduction was sustained during the post-intervention period (1.2/1000 central venous catheter days; RR, 0.49; 95% CI, 0.31-0.78; P ⫽ .003). The relative frequency of specific central venous catheter types in use at the time of infection was as follows: preintervention: peripherally inserted central catheter 46%, triple lumen catheter 50%, hemodialysis catheter plus a triple lumen catheter or peripherally inserted central catheter 2%, hemodialysis catheter alone 2%; active intervention period: peripherally inserted central catheter 40%, triple lumen catheter 32%, hemodialysis catheter plus a triple lumen catheter or peripherally inserted central catheter 24%, subcutaneous venous access device 4%; post-intervention period: peripherally inserted central catheter 33%, triple lumen catheter 28%, hemodialysis catheter plus a triple lumen catheter or peripherally inserted central catheter 31%, hemodialysis catheter alone 3%, subcutaneous venous access device 5%. During the pre-intervention period, the number of central venous catheter-associated bloodstream infections in which gram-negative bacteria were recovered and the number in which gram-positive bacteria were recovered were the same (n ⫽ 21) (Table 3). Klebsiella spp. was the most common gram-negative bacteria, and Enterococcus spp. was the most common gram-positive bacteria. During the active intervention period, the number of central venous catheter-associated bloodstream infections in which gram-negative bacteria were recovered was reduced to 6. The number of central

0 3 4 11 7

0 1 0 7 2

venous catheter-associated bloodstream infections in which gram-positive bacteria were recovered decreased from 21 to 15, with no reduction in the number of infections involving enterococci, including vancomycin-resistant enterococci. Of note, during the active intervention period central venous catheter-associated bloodstream infection due to vancomycin-resistant enterococci occurred predominantly in severely neutropenic oncology patients and severely immunosuppressed patients housed in a single unit, whereas pre-intervention the cases of vancomycin-resistant enterococci causing central venous catheter-associated bloodstream infection were dispersed throughout several units.

DISCUSSION In this prospective, multiple-hospital study, there was a significant reduction in central venous catheter-associated bloodstream infection during the active intervention period in which chlorhexidine bathing was used, compared with pre-intervention when patients were bathed with soap and water or nonmedicated bathing cloths. This reduction was sustained during the 1 year post-intervention period during which chlorhexidine bathing was continued for 88% of the time and there was no direct supervision by study staff. The reduction in central venous catheter-associated bloodstream infection was presumably due to less patient skin colonization with hospital pathogens, resulting in fewer opportunities for central venous catheter contamination, colonization, and subsequent bacteremia. We quantified the number of chlorhexidine baths given and found that patients often received more than 1 bath per day. Compliance with chlorhexidine bathing was high, and chlorhexidine bathing was well tolerated. This study adds to the developing body of evidence associating chlorhexidine bathing with reductions in health-

510 care-associated bacteremia.6-8,12,13 Our study is the first prospective, multiple-hospital study evaluating the use of chlorhexidine bathing as a measure to reduce central venous catheter-associated bloodstream infection. It also is the first study to include a post-intervention period as part of the prospective study. In contrast with the active intervention period when baths administered were recorded on a research flow sheet, during the post-intervention period this was no longer done to allow for a more “real-life” situation. The sustainability of central venous catheter-associated bloodstream infection rate reductions post-intervention lends support to the concept that the infection reduction was related to the use of chlorhexidine bathing; however, we cannot exclude improved or more frequent bathing overall as the principal factor. When the units that had initiated other measures to reduce central venous catheter-associated bloodstream infection were excluded, the subanalysis still demonstrated significant reductions in central venous catheter-associated bloodstream infection rates during both the active intervention and the post-intervention periods. Studies of chlorhexidine bathing have been limited by the before and after study design. One study, however, used a stronger cross-over study design in which there was a simultaneous control in which 2 sides of a medical intensive care unit alternated between chlorhexidine bathing and nonmedicated bathing.6 In this study, Bleasdale et al6 found significantly fewer primary bloodstream infections during the period of chlorhexidine bathing, and these infections were mostly central venous catheter-associated. The bloodstream infections were primarily due to coagulase-negative staphylococci and enterococci. The only study involving more than a few central venous catheter-associated bloodstream infections due to gram-negative bacteria was performed at a long-term acute care hospital where 19 (32%) of the infections pre-intervention involved gram-negative bacteria. As in our study, these gram-negative central venous catheter-associated bloodstream infections were reduced during chlorhexidine bathing, as were central venous catheter-associated bloodstream infections due to coagulasenegative staphylococci.12 The respiratory care unit patients in our study had the highest rate of central venous catheter-associated bloodstream infection during the pre-intervention period and the greatest reduction in central venous catheter-associated bloodstream infection (Table 2). Characteristics specific to respiratory care patients could affect central venous catheter-associated bloodstream infection. For example, tracheostomy can be a risk factor for central venous catheterassociated bloodstream infection, particularly when the central venous catheter is located in the internal jugular vein in close proximity to tracheal secretions,14 and mechanical ventilation alone has been associated with central venous catheter-associated bloodstream infection.12 We did not attempt to study these factors prospectively during the study, but subsequently reviewed data for the unit. Although the percentage of patients receiving mechanical ventilation was the same for the pre-intervention and active intervention

The American Journal of Medicine, Vol 125, No 5, May 2012 periods, the percentage of patients with tracheostomy was significantly greater (P ⬍ .01) during the active intervention period. One could speculate that the reduction of central venous catheter-associated bloodstream infection on this unit might have been even larger if the percentage of patients with tracheostomies had been similar. Although we did not attempt to formally study the cost benefit of chlorhexidine bathing, given an attributable cost estimate of $45,000 per central venous catheter-associated bloodstream infection,9 the cost of chlorhexidine bathing is easily outweighed by the savings from preventing a few central venous catheter-associated bloodstream infections. By using the bathing data collected from the active intervention period, had the hospitals paid for the chlorhexidine baths, there would have been a $4.10 per bath higher cost for the hospitals that switched to chlorhexidine-impregnated cloths from nonmedicated bathing cloths, and a $4.94 to $5.10 per bath increased cost for the hospitals that switched to chlorhexidine-impregnated cloths from soap and water, resulting in an overall increased expenditure ranging from $79,867 to $81,006. There were 21 fewer central venous catheter-associated bloodstream infections during the active intervention period compared with the pre-intervention period. This would be equivalent to a savings of $945,000, which is more than 10 times the cost of chlorhexidine bathing. Nursing staff also found the baths easy to administer and preferable to soap and water in a basin.

Limitations The limitations of this study are the lack of patient-specific data and severity of illness data to determine whether the patient population changed between periods. The need for patient-specific data is apparent as discussed above regarding the respiratory care patients, and others have found discrepant results in different populations. For example, Popovich et al15 found no reduction in central venous catheter-associated bloodstream infection during chlorhexidine bathing of surgical intensive care unit patients, whereas medical intensive care unit patients at the same hospital had significant reductions in central venous catheter-associated bloodstream infection with chlorhexidine bathing.7 In addition, it might have been useful to have the denominator of central venous catheter days stratified by central venous catheter type to uncover patient population or practice changes for the study periods. This was not done because such a stratification is substantially more labor-intensive. Our study was not a randomized double-blind trial, and thus we cannot fully exclude confounding variables. Any bias on the interpretation of bacteremia as central venous catheterassociated during the different study periods should have been minimized because central venous catheter-associated bloodstream infection was publicly reported during the timeframe of this study and application of the National Healthcare Safety Network definition of this infection was monitored by the New York State Department of Health.

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CONCLUSIONS In the 2011 Guidelines for the Prevention of Intravascular Catheter-Related Infections by the Centers for Disease Control and Prevention, daily cleansing with 2% chlorhexidine was given a category II recommendation, which means it is supported by suggestive clinical or epidemiologic studies.16 Our multiple-hospital, 3-phase study demonstrates that chlorhexidine bathing is a simple, well-tolerated infection control intervention that seems to significantly reduce central venous catheter-associated bloodstream infection in intensive care unit/respiratory care unit settings. Chlorhexidine bathing is likely to be an important adjunctive infection control measure for the prevention of central venous catheter-associated bloodstream infection.

ACKNOWLEDGMENTS The authors thank the nursing staff of the study units for careful attention to the chlorhexidine bathing study procedures.

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511 6. Bleasdale SC, Trick WE, Gonzalez IM, Lyles RD, Hayden MK, Weinstein RA. Effectiveness of chlorhexidine bathing to reduce catheter associated bloodstream infections in medical intensive care unit patients. Arch Intern Med. 2007;167:2073-2079. 7. Popovich KJ, Hota B, Hayes R, Weinstein R, Hayden M. Effectiveness of routine patient cleansing with chlorhexidine gluconate for infection prevention in the medical intensive care unit. Infect Control Hosp Epidemiol. 2009;30:959-963. 8. Climo MW, Sepkowitz KA, Zuccotti G, et al. The effect of daily bathing with chlorhexidine on the acquisition of methicillin-resistant Staphylococcus aureus, vancomycin resistant enterococcus and healthcare-associated bloodstream infections: Results of a quasi-experimental multicenter trial. Crit Care Med. 2009;37:1858-1865. 9. Pronovost P, Needham D, Berenholtz S, et al. An intervention to decrease catheter-related bloodstream infections in the ICU. N Engl J Med. 2006;355:2725-2732. 10. Centers for Disease Control and Prevention, National Healthcare Safety Network, Patient Safety Manual. Guidelines and procedures for monitoring CLABSI. March 2010. Available at: http://www.cdc.gov/ nhsn/PDF/pscManual/4PSC_CLABScurrent. Accessed June 7, 2011. 11. Selvin S. Statistical Analysis of Epidemiologic Data. 3rd ed. New York: Oxford University Press, Inc; 2004. 12. Munoz-Price LS, Hota B, Stemer A, Weinstein RA. Prevention of bloodstream infections by use of a daily chlorhexidine baths for patients at a long term acute care hospital. Infect Control Hosp Epidemiol. 2009;30:1031-1035. 13. Evans HL, Dellit T, Chan J, Nathans AB, Maier RV, Cuschieri J. Effect of chlorhexidine whole-body bathing on hospital-acquired infections among trauma patients. Arch Surg. 2010;145:240-246. 14. Lorente L, Jimenez A, Martin MM, et al. Influence of tracheostomy on the incidence of central venous catheter-related bacteremia. Eur J Clin Microbiol Infect Dis. 2009;28:1141-1145. 15. Popovich KJ, Hota B., Hayes R, Weinstein RA, Hayden MK. Daily skin cleansing with chlorhexidine did not reduce the rate of central venous catheter associated bloodstream infection in a surgical intensive care unit. Intensive Care Med. 2010;36:854-858. 16. O’Grady N, Alexander M, Burns L, et al. Health care practices advisory committee, Centers for Disease Control and Prevention. Guidelines for the prevention of intravascular catheter-related infections, 2011. Available at: http://www.cdc.gov/hicpac/BSI/BSI-guidelines2011.html. Accessed June 7, 2011.