Serogrouping and pulsed-field gel electrophoresis analysis of Listeria monocytogenes isolates from cases of human infection In Hungary 2004–2012

Eighty isolates of Listeria monocytogenes cultured from human infections in Hungary between 2004 and 2012 were serotyped by the PCR technique of Doumith et al. [9] and characterised by pulsed-field gel electrophoresis (PFGE). Most of the isolates belonged to two serogroups: 53 isolates (66.3%) to serovar group 4b,4d,4e and 21 isolates (25.8%) to serogroup 1/2a,3a. Although many pulsotypes were identified a particular pulsotype proved highly excelling comprising of 31 isolates after digestion by both ApaI and AscI restriction enzymes. All strains from this pulsotype belonged to serovar group 4b,4d,4e. Interestingly 24% of isolates from invasive samples (cerebrospinal fluid, blood) belonged to two distinct pulsotypes in the less common serovar group 1/2a,3a. Several small clusters of cases caused by isolates with identical pulsotypes were identified.