Dissemination of ST274 Klebsiella pneumoniaeepidemic clone in newborn and adult hospital settings harbouring SHV-2A orCTX-M-15 type extended spectrum β-lactamases-producing knownplasmids

摘要

Molecular epidemiology and genetic features of an extended-spectrum β-lactamase (ESBL) producing Klebsiella pneumoniae epidemic clone (KP-EC) with elevated ciprofloxacin MIC (minimum inhibitory concentration) values from multiple nosocomial outbreaks and sporadic cases between 2006 and 2008 in Hungary were investigated.As a result of continuous monitoring of ESBL-producing KP-ECs, 27 isolates collected from five healthcare facilities were selected for macrorestriction profile analysis by PFGE (pulsed field gel electrophoresis). Of these, 12 strains were isolated from adult inpatients, while 15 strains were from newborns. The MIC values for several antibiotics were determined by agar dilution technique. Molecular typing was further performed by PCR (polymerase chain reaction) and sequencing of several antibiotic resistance genes, plasmid profile analysis, transfer of resistance determinants and multilocus sequence typing (MLST).All isolates showed moderate resistance to ciprofloxacin (MICs ranged from 0.5 to 8 mg L^–1). PFGE revealed the existence of only one genetic cluster defined as EC IV. PstI digestion of plasmid DNA revealed two highly diverse restriction patterns in “adult” and “newborn” isolates corresponding to plasmids from the Hungarian Epidemic Clone and plasmidsisolated from a neonatal nosocomial outbreak in 1998, respectively. Sequenceanalysis of β-lactamase genes from plasmids of 14 selected isolates detectedblaSHV–2a in strains isolated exclusively fromnewborns and blaCTX-M-15 in strains isolatedexclusively from adult inpatients. MLST established that strains of the PFGEcluster belonged to a novel sequence type ST274.ESBL-producing K. pneumoniae isolates belonging to the novelsequence type ST274 appeared in the newborn and adult hospital settings inHungary and acquired SHV-2a or CTX-M-15 type enzymes, respectively. Thus, a newantimicrobial resistance strategy for successful conformation to distincthospital settings was found.