Epidemiology of SHV-type β-lactamase-producing Klebsiella spp. from outbreaks in five geographically distant Hungarian neonatal intensive care units: widespread dissemination of epidemic R-plasmids

One hundred and twenty-six extended-spectrum β-lactamase-producing clinical isolates of Klebsiella spp. were collected in 1998, 2002 and 2003 from seven outbreaks in neonatal intensive care units (NICUs) of five Hungarian county and teaching hospitals. The isolates were multidrug resistant but were susceptible to ciprofloxacin. Pulsed-field gel electrophoresis revealed the existence of 12 distinct genetic clones, 10 of which proved epidemic in the studied NICUs. All isolates harboured plasmids ranging from 2.3 kb to 228 kb, representing 12 diverse plasmid profiles. Sequence analysis of SHV-specific polymerase chain reaction products from 13 representative isolates detected the blaSHV-2a gene in three and the blaSHV-5 gene in seven epidemic clones, respectively. In the majority of isolates the blaSHV genes were on transferable plasmids of 94 kb. EcoRI and PstI digestion of plasmid DNA from transconjugants revealed identical or closely related restriction patterns in nine blaSHV-5-harbouring R-plasmids and in two blaSHV-2a-harbouring R-plasmids carried by strains obtained from geographically distant NICUs. Endemic clones in individual wards or epidemic clones affecting multiple healthcare facilities were not found. However, similarities observed in the size and restriction pattern of the plasmids hints at the multiple transfer of epidemic R-plasmids responsible for a sequence of outbreaks in Hungary.