EFFICACY OF MICROBIAL IDENTIFICATION SYSTEM FOR EPIDEMIOLOGIC TYPING OF COAGULASE-NEGATIVE STAPHYLOCOCCI

The lack of an adequate typing system hampers our understanding of the epidemiology of infections caused by coagulase-negative staphylococci (CoNS). CoNS have become recognized as important nosocomial pathogens and the principal cause of infections associated with invasive device s. Sensitive, specific, and convenient methods are needed to evaluate whether implementing infection control guidelines reduces the risk of nosocomial infections from CoNS and other pathogens. The Microbial Ide ntification System (MIDI) (Microbial ID Inc., Newark, Del.), a semiaut omated system for fatty acid methyl ester analysis, shows considerable promise for clinical and epidemiologic applications. Its predictive a ccuracy and reliability were tested by using epidemiologically related and replicated CoNS isolates as well as CoNS from epidemiologically u nrelated clinical infections, which were obtained from five establishe d hospital culture collections in diverse geographic locations. Two hu ndred isolates were fully characterized in 5 days by one person using MIDI, and the results were similar to those produced by more expensive and time-consuming conventional typing methods. MIDI appears to be a useful screening tool that could be used before more expensive and lab or-intensive molecular methods. It offers important advantages to hosp ital epidemiologists and clinical microbiologists who must identify an d type CoNS isolates.