Prevention of Staphylococcus aureus burn wound colonization by nasal mupirocin

Abstract

Background

There are two important routes for the transmission of Staphylococcus aureus to the burn wound. In the endogenous route, patients naturally carrying S. aureus colonize their own wounds, whereas in the exogenous route burn wounds are cross-infected from other sources. In this study we evaluated the effect of blocking the endogenous route on S. aureus burn wound colonization by mupirocin application in the nose of patients at the time of admission.

Methods

From September 2000 to January 2002 all patients with burns admitted to a single dedicated Burn Centre received nasal mupirocin upon admission. This period was compared to two control periods (C1: July 1999 to July 2000 and C2: January 2002 to January 2003) for S. aureus burn wound colonization. The colonization risk was analysed, adjusting for confounding, with Cox proportional hazard regression.

Results

A total of 98 patients did not have S. aureus burn wound colonization at the time of admission and were, thus, considered at risk for S. aureus acquisition during their stay. As compared to C1, the relative risk of acquiring S. aureus in their wound was 0.48 (95% CI: 0.24–0.97) in the mupirocin period and 0.55 (95% CI: 0.28–1.1) during the C2 period. S. aureus nasal/pharyngeal colonization was a significant independent risk factor for wound colonization (RR: 2.3; 95% CI: 1.2–4.2).

Conclusion

Nasal mupirocin may contribute to risk reduction of S. aureus wound colonization in patients with burns.

Introduction

Patients with burns are at a high risk of contracting nosocomial pathogens and infection. Several studies have shown that the rate of burn wound colonization with Staphylococcus aureus varies considerably [1], [2], [3], [4], [5]. The risk of colonization is related to the total burned surface area (TBSA), the age of the patient, nasal and pharyngeal S. aureus carriage of patients as well as of their health care workers, and the type of care provided by the Burn Centre. Colonization with S. aureus has been associated with delayed wound healing, increased need for surgical interventions and prolonged length of stay at the centre [3], [6]. Transmission of S. aureus occurs often, both between patients and between patients and care takers [7]. Part of S. aureus wound colonizations in patients is of endogenous origin, i.e. their wounds become colonized by the S. aureus strain already present in the patients’ nose or throat at the time of admission [8], [9], [10], [11]. By eliminating nasal carriage, nasal mupirocin could prevent endogenous S. aureus wound colonization.

Topical mupirocin has been widely used to treat nasal S. aureus carriage, particularly during outbreaks of methicillin resistant strains (MRSA) [12], [13]. Mupirocin prophylaxis has been shown to reduce the rate of nasal carriage, and hence, clinical infection in surgical and dialysis patients and in human immunodeficiency virus (HIV) disease [14], [15], [16], [17]. In a single centre study Mackie et al. [18] found a significant reduction in S. aureus wound colonization when using nasal mupirocin combined with selective decontamination of the digestive tract in patients with more than 30% TBSA. Potentially, mupirocin could be used to prevent endogenous colonization of burn wounds. However, the efficacy of standard mupirocin prophylaxis in a Burn Centre has not yet been established.

The aim of the present investigation was to evaluate the effect of a short course of nasal mupirocin on the incidence of S. aureus burn wound colonization.