Characterization of extended-spectrum β-lactamase (ESBL) producing Escherichia coli strains isolated from animal and human clinical samples in Hungary in 2006-2007

The proportion of Escherichia coli non-susceptible to 3(rd) generation cephalosprins from invasive clinical samples has risen in Hungary from 5.1 per cent in 2006 to 15.5 per cent in 2011. The prevalence of ESBL-production in E. coli of animal origin remains unknown. During the first stage of a probe forty-five human and 18 animal ESBL-producing E. coli strains isolated in 2006-2007 were investigated. The human strains were representatively selected from a collection of 113 ESBL-producing isolates sent to the national reference center from local laboratories across the country. A variety of ESBLs were detected (SHV-2, -5, -12, CTX-M-32) with CTX-M-15 being the most common in human and CTX-M-1 the dominant in animal isolates. Genetic characterization revealed that thirty-six human isolates (80 per cent) belonged to either the phylogenetic group (PG) B2 or D. Conversely, 15 animal isolates (83 per cent) proved to be members of the A and B1 commensal PGs. Furthermore 46 per cent of human isolates (21/45) from 12 centres belonged to the international O25-ST131/B2 clone while nine isolates from seven centers showed the O15 serotype. Pulsed-field gel electrophoresis (PFGE) detected 22 and 11 diverse pulsotypes among 45 human and 18 animal isolates, respectively. The human and animal strains did not share any pulsotypes.

Expansion and countrywide dissemination of ST11, ST15 and ST147 ciprofloxacin-resistant CTX-M-15-type beta-lactamase-producing Klebsiella pneumoniae epidemic clones in Hungary in 2005--the new 'MRSAs'?

OBJECTIVES

To investigate the molecular epidemiology of ciprofloxacin-resistant CTX-M-15-producing Klebsiella pneumoniae epidemic clones (ECs) isolated from six nosocomial outbreaks and sporadic cases during 2005 in Hungary.

METHODS

Two hundred and eighty-one extended-spectrum beta-lactamase (ESBL)-producing K. pneumoniae clinical isolates collected from 41 centres were submitted to the National ESBL Reference Laboratory for further investigations. Of the 281 strains, 75 isolates proved to be SHV producers, whereas 6 isolates were ciprofloxacin-susceptible CTX-M-type ESBL producers. One hundred and ninety-six ciprofloxacin-resistant CTX-M-type beta-lactamase-producing isolates collected from 35 centres were subjected to macrorestriction profile analysis. Furthermore, molecular typing was performed by PCR and sequencing of several antibiotic resistance genes, plasmid profile analysis, transfer of resistance determinants and multilocus sequence typing (MLST).

RESULTS

PFGE revealed the existence of three genetic clusters defined as ECs, where 129 isolates belonged to the previously described Hungarian EC (HEC), 46 isolates to epidemic clone II (EC II) and 21 isolates to epidemic clone III (EC III), respectively. All isolates harboured plasmids ranging from 2.0 to 230 kb. PstI digestion of plasmid DNA from transconjugants/transformants revealed diverse restriction patterns from distinct ECs. Sequence analysis of beta-lactamase genes from 19 selected isolates detected bla(CTX-M-15) and bla(OXA-1) in strains from all three ECs and bla(TEM-1) in EC III isolates located on large plasmids. ISEcpI associated with CTX-M-15 was detected only on a 50 kb non-conjugative plasmid from EC III. MLST identified three allelic profiles: ST 15 (HEC), ST 11 (EC III) and the novel ST 147 (EC II), which correspond to the PFGE clusters, respectively.

CONCLUSIONS

In 2005, 97% of all CTX-M-producing K. pneumoniae isolates detected across Hungary were highly ciprofloxacin-resistant CTX-M-15 producers and represented just three stable genetic clones.