Epidemiological typing of coagulase-negative staphylococci by pyrolysis mass spectrometry

Pyrolysis mass spectrometry (PMS) was evaluated for the epidemiological typing of coagulase-negative staphylococci (CNS) in situations in which it was necessary to distinguish between repeated isolation of the same strain from a single patient (genuine infection) and coincidental isolation of unrelated strains (contamination). Thirteen CNS isolates were examined, consisting of five pairs, each pair isolated from a single patient, and three unrelated strains. PMS analysis gave results equivalent to a conventional typing system comprising antibiogram, biotype and plasmid profile analysis. Both methods facilitate differentiation between genuine infection with CNS and the isolation of contaminants. The speed, reproducibility, versatility and relatively low cost of PMS suggest that it may be a valuable new technique for the epidemiological typing of CNS in routine clinical settings.