Pulse-electrotypes of Listeria monocytogenes strains, isolated in Moscow

The characterization of the pulse-electrotypes of L. monocytogenes, isolated in 2003-2004 in Moscow from different sources, is presented. Among the cultures, isolated from humans, one outbreak pulse electrotype was detected and from different objects in buildings where a wide variety of food products was produced several probably related and unrelated pulse-electrotypes were obtained. The conclusion was made that several independent L. monocytogenes clones existed on the territory of Moscow, and many products supplied to retail trade and public catering enterprises were contaminated with these clones. Pulse electrophoresis was shown to be the most effective method for intraspecific typing and the study of the molecular epidemiology of listeriosis. Grounds for the necessity to improve the microbiological diagnostics of L. monocytogenes infection are given.