Nasal and Cutaneous Flora Among Hemodialysis Patients and Personnel: Quantitative and Qualitative Characterization and Patterns of Staphylococcal Carriage

Nasal and Cutaneous Flora Among Hemodialysis Patients and Personnel: Quantitative and Qualitative Characterization and Patterns of Staphylococcal Carriage Simeon E. Goldblum, M.D., John A. Ulrich, Ph.D., Richard S. Goldman, M.D., and William P. Reed, M.D. Staphylococcal sepsis is a leading cause of morbidity and mortality among chronic hemodialysis (HD) patients. We studied nasal and cutaneous flora of HD patients and personnel and their patterns of staphylococcal carriage. HD patients had significantly increased cutaneous total bacterial colony counts (p < 0.01) as well as both nasal (p < 0.00(1) and cutaneous (p < 0.0001) carriage of Staphylococcus aureus compared to personnel. Cutaneous staphylococcal carriage could be significantly correlated with nasal carriage (p < 0.01). Cutaneous streptococcal species and gram-

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N INCREASED incidence of septic complications has been described among chronic hemodialysis (HD) patients. 1-3 Several investigators have found the majority of these infections to be vascular access-related.4-6 Because of the close proximity of the vascular access site to the skin barrier, the cutaneous flora of HD patients has been studied. 7-10 Ralston et al. first noted that vascular access site-related staphylococcal infections occurred in a small number of HD patients who were established carriers of the offending phage type on the skin of the access-bearing limb. 7 Rebel et al. found that nasal or perineal carriers of Staphylococcus aureus were predisposed to colonization and infection of the vascular access site with the same organism. 8 More recently, we have reported significantly increased nasal and cutaneous staphylococcal carriage among HD patients. 9 Nasal staphylococcal carriage could be significantly correlated with cutaneous carriage over vascular access site and cutaneous carriage with previously documented staphylococcal infections. Cutaneous carriage of either streptococcal species or gram-negative bacilli was not different from normals. The increased staphylococcal carriage among HD patients has been confirmed by Kiramani et al., 10 and corresponds with staphylococcus being the etiologic agent most frequently causing vascular access-related sepsis in HD patients. 4-6 A causal relationship between staphyococcal carriage and systemic infection has been shown among parenteral drug abusers. 11.12 These studies were longitudinally performed to quantitatively and qualitatively evaluate the nasal

negative bacilli were not different between patients and personnel. Staphylococcal phage typing of nasal isolates from staphylococcal carriers revealed a mean of 90% of isolates from each subject belonging to a predominant phage type. Predominant nasal staphylococcal phage types corresponded with respective predominant cutaneous phage types in 93% of HD patient carriers. These studies substantiate autoinoculation of S. aurells from the nasal vestibule to the skin overlying the vascular access site.

and skin flora of HD patients and personnel over a period of at least 6 mo. Staphylococcal phagetyping was used to elucide patterns of staphylococcal carriage among subjects within HD units. MATERIALS AND METHODS

Subjects Admitted to the Study HD patients and personnel in the HD units at the Albuquerque VA Medical Center and the University of New Mexico Hospital all gave informed consent. Patients admitted to the study were undergoing chronic triweekly HD, did not have dermatologic abnormalities outside the expected range of skin conditions associated with chronic renal insufficiency, and had not received systemic antibiotics during the 10 days either prior to or during the study. All subjects were interviewed and medical records reviewed to record age, sex, allergies, dermatologic problems, duration ofHD, underlying renal disease, serum creatinine, number, type, and location of vascular access(es), and the presence of any other nonrenal diseases.

Instructions to Subjects All subjects were instructed not to use any germicidal agents (excluding underarm deodrants) or lotions on their skin during the study period. Nonbacteriostatic soap (Sweetheart soap, Purex Corp., Carson, California) and shampoo (Purpose shampoo, Johnson and Johnson Products, Inc., New Brunswick, New Jersey) were given to all subjects for routine use. From the Departments of Medicine and Microbiology. Veterans Administration Medical Center and University of New Mexico School of Medicine. Albuquerque. N.M. This work was supported. in part, by the Kidney Foundation of New Mexico. Reprint requests should be addressed to Simeon E. Goldblum. M.D .. Research Service (151), VA Medical Center. 2100 Ridgecrest Drive S.E .. Albuquerque, N.M. 87108 © 1982 by The National Kidney Foundation. Inc. 0272-6386/82/020281-06$01.00/0

American Journal of Kidney Diseases, Vol. II. No.2. September 1982

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Table 1.

Subjects were instructed not to bathe or shower for at least 2 hr prior to sampling.

Skin Preparation Skin disinfection procedures for all HD patients were standardized. The vascular access-bearing limb for each HD patient was wet to above the elbow and the volar aspect of the upper extremity scrubbed from above the elbow to the wrist for one minute with the germicidal agent. Providone-iodine (Betadine) was used for the first 13 wk of the study, followed by 4% chlorhexidine gluconate in a detergent base (Hibiclens) for the next 13-wk period. Scrubbed areas were air dried and wrapped in sterile towels until the onset of the HD procedure. All scrubbing procedures were performed by a single individual in each of the two HD units.

Sampling and Culture Techniques Skin contact was made using Rodac plates (each containing 16 ml of sheep blood agar) over the sample site for 1-3 sec irpmediately prior to skin disinfection. 9.13.14 The HD patients were sampled once a week over the vascular access site and over the analogous site on the contralateral limb. After the longest interdialysis interval (66-68 hr). The HD personnel were similarly cultured over both ventral wrists. Skin contact plates were then aerobically incubated at 3rC for 48 hr and quantitatively and qualitatively evaluated for total colony counts, S. aureus, streptococcal species, and gram-negative bacilli. Total colony counts too numerous to accurately quantitate were assigned a count of 500 colonies and overgrown confluent plates were discarded. Polyester fiber-tipped swab cultures from the anterior nasal vestibule were also obtained weekly from both HD patients and personnel. The swabs were immediately streaked on sheep blood agar plates and aerobically incubated for 48 hr at 3rC. The nasal cultures were qualitatively evaluated for the presence of S. aureus.

Bacteriophage Typing of Isolates of Staphylococcus Aureus Isolates of S. aureus from nasal and cutaneous cultures obtained from HD patients and personnel were bacteriophagetyped as previously described 17·19 with several modifications. A standardized collection of S. aureus and typing bacteriophages (Center for Disease Control, Atlanta, Ga.) together with a Steer's replicator (Melrose Machine Shop, Woodlyn, Pa.) were used. Phages were titred to the highest dilution just failing to give confluent lysis and this dilution was then used as the routine test dose (RTD). Each S. aureus isolate was subcultured and incubated in the presence of a panel of the standardized, titred bacteriophages. The isolates were typed by their patterns of susceptibility to lysis by the phages. Nonreacting isolates were retested using phage titres of 100 RTD.

RESULTS

Subjects Admitted to the Study

A total of 46 HD patients and 24 HD personnel were initially entered into the study. Four subjects

Subjects Admitted to Study

Initial entry into study Completion of total study Mean Age (years) Range (years) Male: Female Ratio Glucose intolerance (% subjects)

HD Patients

HD Personnel

46 30 53 18-37 3:2

24 12 35 21-59 1 :2

33%

0%

from the patient group and three from the personnel group were discarded from the study because of adverse reactions to either disinfectant. Of the remaining 42 patients, 30 had complete (>23 of 26 samplings) baseline predisinfection data and 25 had complete postdisinfection data. Of the remaining 21 personnel, none had complete predisinfection data throughout the duration of the study. The characteristics of the study population are summarized in Table 1. Quantitative Predisinfection Cultures

HD patients had significantly higher mean predisinfection total bacterial colony counts (232.1 ± 46.3) compared to HD personnel (97.9 ± 29.9) at p < 0.01. This difference could be demonstrated over the entire study period (Fig: 1). In each subject, the vascular access-bearing limb was compared to the contralateral limb. Predisinfection total colony counts could not be statistically correlated with site of vascular access(es). The means of these weekly total colony counts showed no statistically significant downward or upward linear time trend over the entire 26-wk study period using skin cultures obtained from either HD patients or personnel. The single most numerically important aerobic organism contributing to total colony counts was coagulase negative staphyloCoCCI.

Qualitative Predisinfection Cultures

The results of nasal and cutaneous cultures obtained from either HD patients or personnel were separately pooled and the number of cultures positive for S. au reus , streptococcal species, and gram-negative bacilli determined and expressed as percent of total interpretable cultures (i.e., not overgrown) (Fig. 2). After noninterpretable cultures were discarded (15 from patients, one from personnel), 916 nasal and 946 skin cultures from HD patients and 364 nasal and 367 skin cul-

NASAL-CUTANEOUS FLORA IN HD PATIENTS

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tures from HD personnel were included. Nasal and cutaneous isolates of S. aureus obtained from HD patients were significantly greater (p < 0.0001 andp < 0.0001, respectively) than those obtained from HD personnel. Isolates of both streptococcal species and gram-negative bacilli obtained from HD patients and personnel were not significantly different (Fig. 2). Thus , the qualitative differences in the nasal and cutaneous flora of HD patients were confined to S. aureus . Epidemiologic Patterns of Staphylococcal Carriage Within the HD Unit

In this study, we have shown nasal and cutaneous carriage to be significantly increased among

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HD patients compared to personnel. Of 30 patients with complete data, percent positive interpretable nasal cultures for S. au reus were determined (Fig. 3). Clearly demarcated subpopulations based on percent nasal staphylococcal carriage could not be demonstrated. A positive correlation could be demonstrated between nasal and cutaneous staphylococcal isolates in these same 30 patients with a Spearman correlation coefficient of +0.90 (Fig. 4) , a correlation significant at p < 0 ;01. Data from - 1100 samplings in which simultaneous nasal and cutaneous cultures were obtained and evaluated for S. aureus, were examined for predictive value in the clinical setting. A pa-

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tient with a positive nasal culture had a 26% probability of having a simultaneously positive skin culture. A negative nasal culture was associated with a negative skin culture in 97.5% of simultaneous samplings. The presence or absence of S. aureus could not be significantly correlated with vascular access site(s). Staphylococcal phage typing was performed on all interpretable nasal and cutaneous isolates of S. aureus. Seventeen subjects (three personnel and

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14 patients) who each grew S. au reus from > 50% of their nasal cultures (mean = 85.2%) were analyzed (Fig. 5). Each of these 17 subjects' predominant phage type persisted > 50% of the study period (mean = 89.9%). Only 11 of the 14 patients had complete data (Fig. 3) . Predominant nasal staphylococcal phage types corresponded with their respective predominant cutaneous phage types in 13 of the 14 (92.9%) HD patients but in only one of the three (33 .3%) HD personnel. These data substantiate the phenomenon of autoinoculation of S. aureus from the nasal vestibule to the skin overlying the vascular access site. The increased nasal-cutaneous phage type correspondence among HD patients suggests an altered skin barrier more hospitable to S. aureus . Of 26 HD patients who initially had nasal cultures negative for S. aureus, only three became persistent nasal staphylococcal carriers. All three acquired phage types found exclusively among HD patients (phage type 3A-3C-55"71). Both of the two phage types found among HD personnel were also found among patients. Multiple phage types were found in each of the two separate HD units with partial phage type overlap, including phage types 29, 71 , and 96. Eleven of 30 (37%) HD patients completing the whole study had > 50% of their nasal cultures positive for S. aureus. Characteristics of these staphylococcal carriers have been summarized in Table 2. When 10 patients with > 60% of their nasal cultures positive for S. aureus were compared with 12 patients with < 10% culture posi-

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NASAL-CUTANEOUS FLORA IN HD PATIENTS

Table 2. Characteristics of Staphylococcal Carriers Versus Noncarriers Among Hemodialysis Patients

Mean age (years) Sex (M:F) Race (W:AI* :8) Mean duration HD (months) Glucose intolerance Insulin depndence

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Noncarriers

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tivity, no significant differences could be demonstrated between the two groups for mean age, male-to-female ratio, race, mean duration of HD glucose intolerance, or insulin dependence. ' DISCUSSION

HD-associated sepsis is often due to vascular access site-related staphylococcal infections. 4-7 We have compared the nasal and cutaneous flora of HD patients to HD unit personnel and have longitudinally studied their patterns of staphylococcal carriage over an extended period of time. HD patients displayed significantly increased total aerobic bacterial colony counts on the skin and increased nasal and cutaneous carriage of S. au reus compared to HD personnel; cutaneous carriage of either streptococcal species or gramnegative bacilli was not significantly different between the two groups. Local disinfection did not alter the predisinfectant total bacterial counts over the study period. Cutaneous staphylococcal carriage was significantly higher among nasal carriers but could not be statistically correlated with site of vascular access. Staphylococcal phagetyping revealed persistence of one predominant staphylococcal phage type within each respective subject throughout the study period. Seventeen staphylococcal carriers had a mean of 90% of their isolates belonging to the predominant phage type of each subject. Persistent staphylococcal carriage could not be correlated with the duration of HD. This increased staphylococcal carriage among HD patients remains unexplained. St'aphylococcal carriage was not more likely over vascular accessbearing limbs than analogous non-bearing sites. This suggested that triweekly skin disinfection or vascular access cannulation did not exert significant local effects to promote staphylococcal carriage. Increased staphylococcal carriage has been reported among parenteral drug abusers 11,12

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and insulin-dependent diabetics. 20,21 The inc.reased staphylococcal carriage among HD patIents could not be ascribed to either glucose intolerance or insulin dependence (Table 2). Neither could HD unit exposure alone explain this increased staphylococcal carriage. HD patients have 12-18 hr/wk exposure to the in-hospital environment compared to at least 40 hr for pers?nnel; y.et, the former group display a sigmficantly Increased carriage rate. It is possible that metabolic abnormalities associated with chronic renal insufficiency might alter patterns of nasal and skin flora. Excretion of an altered sweat,22-24 increased quantities of urea nitrogen in the skin 25 and saliva 26-29 and the abnormal biochemical profile of uremic breath 30 all might alter the nutritional opportunities or exert inhibitory influence for bacterial growth on skin or within the nasal vestibule. Alternatively, bacterial adherence of S. aureus to nasal epithelial cells might be enhanced in patients with renal insufficiency. In conclusion, a subpopulation of HD patients are persistent nasal staphylococcal carriers over an extended period of time. Since there appears to be a relationship between qualitative 8 ,12 and quantita. nasaI cultures 31 and subsequent staphylococcal tIve sepsis, perhaps this HD patient subpopulation should be routinely identified with serial nasal cultures and prophylactic measures instituted. The risk of staphylococcal infection could not be addressed as our patient popUlation exhibited no staphylococcal infection over the 6-month study period. Antibiotic nasal ointments and sprays, 32-35 or parenteral vancomycin 35 might be studied in this setting. Staphylococcal-produced coagulase could playa role in vascular access thromboses. Thus, the potential morbidity and mortality related to coagulase positive staphylococcus among HD patients might prove great. Additional understanding of the staphylococcal-HD patient interaction might offer prophylactic and/or therapeutic modalities of intervention for this group of patients. ACKNOWLEDGMENTS -:he authors thank Dr. Pratap Avasthi for contributing patients to the study and the hemodialysis unit personnel at both the Albuquerque VA Medical Center and University of New Mexico Hospital for their cooperation with patient scheduling and culture sampling. We thank Ms. G. Zastro for her administrative and microbiologic contribution.

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19. DHEW, PHS, CDC. Staphylococcus typing phages. B39: 1-9; B40:1-15, June, 1976 20. Smith JA, O'Connor JJ, Willis AT: Nasal carriage of staphylococcus aureus in diabetes mellitus. Lancet 11:776777, 1%6 21. Tuazon CU, Perez A, Kishaba T , et al: Staphylococcus aureus among insulin-injecting diabetic patients. An increased carrier rate . JAMA 231:1272, 1975 22 . Lobitz WC Jr , Mason HL: Chemistry of palmar sweat. Arch Dennatol Syph 57:907-915 , 1948 23. Gorden RS Jr, Thompson RH, Thrasher D, et al: Genesis of the sweat: Plasma urea concentration gradient. J Invest Derm 66:218-221, 1976 24. Prompt CA, Quinton PM, Kleeman CR: High concentrations of sweat calcium, magnesium and phosphate in chronic renal failure. Nephron 20:4-9, 1978 25. Bollinger A, Gross R: Water soluble compounds (nonkeratins) associated with the skin flakes of the human scalp. Aust J Exp Bioi Med Sci 34:219-224, 1956 26. Dahlberg WH , Sreebny LM , King B: Studies of parotid saliva and blood in hemodialysis patients . J Appl Physiol 23: l00~ 108, 1967 27 . Blum M, Zurkowsky S, Gilad J , et al: Salivary phosphate and calcium concentrations in uremia. Clin Neph 12: 191- 192, 1970 28. Goll RD, Uthman AA, Mookerjee BK: Comparison of salivary and serum biochemical parameters in chronic uraemia and during hemodialysis. Kidney lnt (Abstr) 8:425. 1975 29 . Shannon IL, Feller RP, Eknoyan G, et al: Human parotid saliva urea in renal failure and during dialysis . Arch Oral Bioi 22:83-86, 1977 30. Simenhoff ML, Burke IF, Saukkonen n, et al: Biochemical profile of uremic breath. N Engl J Med 297:132~ 135, 1977 3 I. White A: Relationship between quantitative nasal CUltures and dissemination of staphylococci. J Lab Clin Med 58:273-277, 1961 32. Stratford B, Rubbo SD, Christie R et al: Treatment of the nasal carrier of staphylococcus aureus with framycetin and other antibacterials. Lancet II: 1225- 1227, 1960 33 . Varga DT, White A: Suppression of nasal, skin and aerial staphylococci by nasal application of methicillin . J Clin Invest 40:2209-2214, 1961 34 . White A: The use of gentamicin as a nasal ointment. Am J Med Sci 248:86/52-89/55, 1%4 35 . William ill, Waltho CA, Ayliffe GAJ, et al: Trials of five antibacterial creams in the control of nasal carriage of staphylococcus aureus. Lancet TI:390-392, 1967 36. Morris AJ, Bilinsky RT: Prevention of staphylococcal shunt infections by continuous vancomycin prophylaxis. Am J Med Sci 262:87-92, 1971