Gastro-intestinal carriage of MRSA in patients with community-acquired diarrhoea

Abstract number: P651

Cope N.K., Smullen J., Kerr K.G., Snelling A.M.

Objectives: There is increasing concern about cases of infection with meticillin resistant Staphylococcus aureus (MRSA) in the community, but comparatively little work has been done on reservoirs for MRSA outside the hospital. Since S. aureus has the potential to colonise the gut and may be enterotoxigenic, we sought to determine the prevalence of MRSA in diarrhoeal samples originating from the community.

Methods: During a year-long survey, faecal samples from non-hospitalised patients submitted for standard investigation of diarrhoeal symptoms were also screened for S. aureus by the diagnostic laboratory. Samples were cultured on mannitol salt agar at 37°C in aerobic conditions for 48 hours. S. aureus isolates were identified by latex agglutination and DNAse activity, and MRSA were confirmed by resistance to cefoxitin.

Results: Of 2624 faecal samples investigated, 405 (15.4%) tested positive for the presence of S. aureus. Of these, 384 (14.6% of all samples) yielded meticillin sensitive S. aureus (MSSA) and just 21 (0.8%) yielded MRSA. The latter originated from patients aged 3 months to 95 years and 15 (71%) of these had no previous history of colonisation or infection with MRSA. However, the majority, (16/21 or 76%) of the MRSA isolates came from patients aged over 75 years. The overall carriage rate of MRSA in stool samples from non-hospitalised individuals aged over 75 years, with diarrhoea was 11% (16 of 144 specimens). This compares to an MRSA gastrointestinal prevalence of 7.6% amongst elderly patients with nosocomial diarrhoea in our hospital over the same time period.

Conclusion: MRSA colonisation is a risk factor for subsequent infection. This study has demonstrated that the gastrointestinal tract can be a significant reservoir of MRSA in the over 75s living in the community, and it is possible that strains are being disseminated via diarrhoeal episodes. This has consequences for control of MRSA in the community, where emphasis is often placed on controlling just nasal and skin colonisation. Further studies of faecal MRSA are warranted, including their enterotoxin status and risk factors for gastrointestinal colonisation.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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