Comparison of the effect of detergent versus hypochlorite cleaning on environmental contamination and incidence of Clostridium difficile infection

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Abstract

To determine how best to decontaminate the hospital environment of Clostridium difficile, we carried out a cross-over study on two elderly medicine wards to determine whether cleaning with a hypochlorite disinfectant was better than using neutral detergent in reducing the incidence of C. difficile infection (CDI). We examined 1128 environmental samples in two years, 35% of which grew C. difficile. There was a significant decrease of CDI incidence on ward X, from 8.9 to 5.3 cases per 100 admissions (P<0.05) using hypochlorite, but there was no significant effect on ward Y. On ward X the incidence of CDI was significantly associated with the proportion of culture-positive environmental sites (P<0.05). On ward Y the only significant correlation between CDI and C. difficile culture-positive environmental sites was in patient side-rooms (r=0.41, P<0.05). The total daily defined doses of cefotaxime, cephradine and aminopenicillins were similar throughout the trial. These results provide some evidence that use of hypochlorite for environmental cleaning may significantly reduce incidence of CDI, but emphasize the potential for confounding factors.

Introduction

Clostridium difficile is the major infective cause of hospital-acquired diarrhoea. Despite increasing awareness of the need to avoid high-risk antibiotics in susceptible elderly patients, reports of C. difficile infection (CDI) continue to increase in England and Wales.1 In addition to hands, environmental contamination is considered an important factor in hospital-acquired infections.2., 3. However, there is little evidence of how best to decontaminate the hospital environment.4

Spores may persist in the hospital environment for months, and are resistant to many commonly used cleaning agents.5 We reported widespread environmental contamination of elderly medicine wards, which tends to increase when detergent-based cleaners are used.6 Daily detergent-based cleaning of side-rooms used for isolation of patients with CDI still led to 25% of all environmental samples taken over four-week periods being contaminated with C. difficile, down from 35% at the start of the study.7 Cleaning agents also show marked differences in their ability to promote sporulation of C. difficile, which can be enhanced when cultured in faeces exposed to chlorine-free cleaners.8

It is unclear, however, whether these laboratory findings have relevance in vivo. We, therefore, carried out this study to determine whether environmental cleaning with a hypochlorite disinfectant as compared with a neutral detergent could reduce the incidence of CDI.

Section snippets

Methods

We carried out a two-year (March 1999–February 2001) ward-based cross-over study to compare the effect of environmental cleaning with either hypochlorite (Saniclor, Henkel Ecolab Professional Hygiene Ltd, Wiltshire, UK; 1000 ppm available chlorine) or neutral liquid detergent (Hospec, Youngs Detergents Lancare Ltd, Cheshire, UK; 1/1000 dilution) on CDI incidence in an endemic setting, on hand carriage by healthcare workers and environmental prevalence of C. difficile. Two elderly medicine wards

Results

We examined 1128 environmental samples, of which 35% were C. difficile positive. A comparison of the two cleaning regimens indicated a significant decrease in CDI on ward X, from 8.9 to 5.3 cases per 100 admissions (P<0.05), associated with the use of hypochlorite. This represented 17 fewer cases of C. difficile cytotoxin-positive diarrhoea during hypochlorite cleaning (N=38) compared with detergent cleaning (N=21) (Figure 1). On ward Y, however, there was no similar significant effect; CDI

Discussion

In general evidence for an important role for environmental contamination in the aetiology of hospital-acquired infection is poor, and several attempts to reduce infection rates by enhancing environmental cleaning have proved unsuccessful.10., 11., 12. Not surprisingly, floor cleaning with either detergent or disinfectant did not affect nosocomial infection rates.10 Recently Pittet et al.12 also found that the incidence of nosocomial infections did not change during a four month trial of

Acknowledgements

We thank the Hospital Infection Society and the Trustees of The General Infirmary at Leeds for research grants that made this study possible. The invaluable support of nursing and domestic staff on the elderly medicine wards is also gratefully acknowledged.

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