Staphylococcus aureus nasal carriage in 104 cirrhotic and control patients A prospective study

Journal of Hepatology 1999; 30:249-253 Printed in Denmark • All rights reserved Munksgaard. Copenhagen

Copyright © EuropeanAssociation for the Study of the Liver 1999 Journal of Hepatology ISSN 0168-8278

Staphylococcus aureus nasal carriage in 104 cirrhotic and control patients

A prospective study Christian Chapoutot 1, Georges-Philippe Pageaux 1, Pierre-Francois Perrigault 2, Zouberr Joomaye 3, Pascal Perney 3, Helene Jean-Pierre 4, Olivier Jonquet 5, Pierre Blanc 1 and Dominique Larrey 1 1Department of Hepato-Gastro-Enterology, 21ntensive Care Unit B, 3Department of lnternal Medicine E, 4Department o f Microbiology and 5Department of lnfectious Diseases, School of Medicine o f Montpellier, France

Background~Aims: Bacterial infections, specially Staphylococcus aureus (S. aureus) septicemia, remain a leading cause of death following liver transplantation. It has been demonstrated that nasal carriage of S. aureus is associated with invasive infections in patients undergoing hemodialysis and could be decreased by use of antibiotic nasal ointment. However, in cirrhotic patients, the frequency of nasal carriage is unknown. The aims of this study were to determine the prevalence of S. aureus nasal carriage in cirrhotic patients and to assess nosocomial contamination. Methods: One hundred and four patients were included in a prospective study, 52 cirrhotic and 52 control (hospitalized patients without cirrhosis or disease which might increase the rate of nasal carriage of S. aureus). On admission and after a few days of hospitalization, nasal specimens from each anterior naris were obtained for culture. S. aureus was identified by the gram strain, positive catalase and coagulase reactions; antibiotic susceptibility was determined using a disk-diffusion test. Results: Both groups were similar with regard to age

and sex. The prevalence of nasal colonization on hospital admission was 56% in cirrhotic patients and 13% in control patients (p=0.001). After an average of 4 days, 42% of cirrhoties and 8% of control patients were colonized (p=0.001), without any nosocomial contamination. Three strains out of 29 were oxacillin-resistant in cirrhotic patients, and none in controls (p>0.05). There was no statistical difference in carriage rate according to sex, age, cause of cirrhosis and Child-Pugh score. Previous hospitalization (OR, 6.3; 95% CI, 2.3 to 19.9; p=0.0006) and cirrhosis (OR, 4.4; 95% CI, 1.5 to 13.4; p=0.0048) were independent predictors of colonization. Conclusion: Cirrhotic patients had a higher S. aureus nasal carriage rate than control subjects. Previous hospitalization and cirrhosis diagnosis were correlated to nasal colonization. Further studies are necessary to determine if nasal decontamination could reduce S. aureus infections after liver transplantation.

ESPITE ADVANCES in prevention, diagnosis and

the 2 months after surgery, or a contributory factor to death in 29% of patients (2). About 60% of infections are caused by gram-positive microorganisms, and Staphylococcus aureus (S. aureus) represents 20% of all these bacterial infections (2,4). S. aureus is a common inhabitant of the skin, and nasal carriage is the principal endogenous reservoir for infection (5-8). The postulated sequence which leads to auto-infection is initiated with S. aureus nasal carriage. The organisms are then disseminated via hand carriage to other sites of the body where infection might occur if there is a break in the dermal surfaces by surgical incision or vascular catheterization (9). Auto-infection is common in patients undergoing hemodialysis, continuous ambulat-

D treatment, bacterial infections remain a major cause of morbidity and mortality in the weeks following a liver transplantation. Infections are the second most frequent complication after acute rejection (1). Bacterial infections occur in the first 8 weeks posttransplantation in 30 to 55% of patients (2-4). They are the main cause of death in 14% of patients who die within Received 23 February; revised 1 September; accepted 8 September 1998

Correspondence: Georges-Philippe Pageaux, D6partement d'H6pato-Gastro-Ent6rologie, H6pital St Eloi, Avenue Bertin Sans 34295 Montpellier Cedex 5, France. Tel: +33 4 67 33 70 62. Fax: +33 4 67 52 38 97.

Key words: Cirrhotic patients; Staphylococcus aureus.

Nasal

carriage;

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ory peritoneal dialysis or in surgical patients (9). In these populations, when the nares are topically treated with mupirocin to eliminate nasal carriage, in most cases S. a u r e u s also disappears from other areas of the body, and this treatment significantly reduces the incidence of infection (10-15). The prevalence of nasal carriage of S. aureus in cirrhotic patients is unknown. If this prevalence is important, nasal decontamination of S. aureus could be useful in this population before liver transplantation in order to reduce infectious mortality. The purpose of this prospective study was to determine the prevalence of nasal carriage of S. aureus among hospitalized cirrhotic patients compared to a control group, to assess the occurrence of nasal contamination during the hospitalization, and to test the susceptibility of strains to oxacillin.

Patients and Methods Selection of patients To be included in the study, volunteers had to give informed consent, and had to be able to comply with the protocol. The study population consisted of two groups of patients hospitalized in the Gastroenterology and Hepatology Department, in St Eloi Hospital, Montpellier, between May and December 1996. We enrolled all cirrhotic patients aged between 18 and 80 years. The diagnosis of cirrhosis was based on needle liver biopsy findings. Subjects were ineligible for the study if they had participated in any other investigative drug trial within 60 days or were receiving therapy with systemic antistaphylococcal antibiotics, topical intranasal antibiotic or immunosuppressive treatment, 3 months before the enrolment. The other exclusion criteria included infection with the human immunodeficiency virus, presence of renal disorders which required hemodialysis or continuous ambulatory peritoneal dialysis, insulin-dependent diabetes mellitus, atopic dermatitis, intravenous drug and addiction, and hospitalization for less than 72 h. Medical staff was also excluded. Controls were recruited among non-cirrhotic patients hospitalized at the same time and in the same department as cirrhotic subjects, and were selected on the basis of identical exclusion criteria. They were matched to cirrhotic patients for sex and age.

Study design Nasal swabs were taken within 24 h of admission in both groups, before all therapeutic or diagnosis procedures, and at the end of hospitalization, on the same day for cirrhotic and control, or within 8 days. When hospitalization was prolonged, a nasal specimen was obtained every week.

Microbiologic evaluation Nasal specimens for culture were obtained by 5 rotations in each anterior naris according to the technique described by Reagan et al. (15). All nasal swabs were sent to the bacteriological laboratory within 1 h. Both swabs were cultured on Columbia sheep-blood agar, Chapman, and incubated at 35°C for 48 h. Isolates were identified as S. aureus if staining showed gram-positive cocci in clusters, and if the results of catatase, coagulase (on rabbit plasma), and latex agglutination (Pastorex Staph Plus) tests confirmed the diagnosis. Susceptibility of all S. aureus isolates was determined by disk-diffusion testing using disks (Mueller Hinton) containing oxacillin (5/~g).

Definition of carriage We defined staphylococcal carriage as the presence of microorganisms in at least one culture for two nares. 250

Data analysis For univariate analysis of qualitative factors, Chi-square or Fisher's exact tests were used. Means were compared with Student's t-test. Multivariate analysis was done using a stepwise logistic regression model. The significant level used was 5°/,, (p