Nosocomial Infectious Bacterial Contamination onResidents' White Coats and Neckties / 대한임상미생물학회지

BACKGROUND: Doctors' white coats and neckties can become contaminated with potentially pathogenic bacteria and have a possibility of causing cross infections. Our objective was to determine the level of bacterial contamination and detect methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and Clostridium difficile present on the white coats and neckties of residents. METHODS: We sampled 28 long-sleeved white coats and 14 neckties worn by residents. The tested sites for white coats were the cuffs and lower front surfaces, and for neckties, the lower surfaces. Impressions of these sites were taken with the plates containing blood agar (BAP), mannitol salt agar supplemented with oxacillin (6microgram/mL), enterococcus screening agar supplemented with vancomycin (6microgram/mL) and phenyl ethanol agar. The colonies grown on each plate were Gram stained and identified by standard microbiological methods. RESULTS: Of the 28 white coats, 7 (25.0%) carried MRSA, and of the 14 neckties, 1 (7.1%) carried MRSA. The majority of white coats (96.4%) and all neckties (100.0%) carried methicillin-resistant coagulase negative staphylococci (MRCNS). None of the white coats and neckties carried VRE or C. difficile. CONCLUSION: Our results showed that white coats and neckties worn by residents were contaminated with MRSA and MRCNS. The preventive measures for clothing-borne cross contamination should be considered, especially when performing invasive procedures or having close contact with patients.

Evaluation of MRSASelect for Discrimination of Methicillin-resistant Staphylococcus aureus from Other Staphylococci / 임상검사와정도관리

BACKGROUND: It is now recognized that screening for methicillin-resistant Staphylococcus aureus (MRSA) in hospital is an effective infection control measure, and selective media-based methods have been commonly used. MRSASelect (MRSAS; Bio-Rad, Hercules, CA, USA) is MRSA selective agar incorporating chromogenic enzymatic substrates, and have been found to be more sensitive and specific than other selective media. The aim of present study was to evaluate MRSAS for discrimination of MRSA from other staphylococci by comparison with mannitol-salt agar with oxacillin (MSO) which is widely used as a MRSA selective medium. METHODS: Ninety-eight staphylococcal strains which were isolated from blood culture specimen, representing 16 MRSA, 6 methicillin-susceptible S. aureus, 59 methicillin-resistant coagulase- negative staphylococci (MRCNS), and 17 methicillin-susceptible coagulase-negative staphylococci were tested. The isolated colonies from pure culture were directly inoculated onto MSO and MRSAS respectively. On MRSAS any growth appearing pink after 24 hours incubation, and on MSO any growth appearing yellow after 48 hours incubation was interpreted as positive for the presence of MRSA. RESULTS: Sensitivities of MRSAS and MSO for MRSA detection were equal (93.8%). Specificities for MRSA discrimination from other staphylococci were 98.8% and 89.0%, and especially from MRCNS were 100% and 84.7%, for MRSAS and MSO, respectively. CONCLUSIONS: The MRSAS showed equal sensitivity compared with MSO for the detection of MRSA. MRSAS showed higher specificity than MSO in discrimination MRSA from MRCNS. It was suggested that the implementation of MRSAS in MRSA screening could decrease the work needed for MRCNS identification.