Epidemiology of hospital-acquired Klebsiella pneumoniae producing CTX-M b-lactamases in Slovenia

Abstract number: 1733_174

Me[scaron]ko Meglic K., Koren S., Palepou M.F.I., Karisik E., Livermore D.M., Andlovic A., Jeverica S., Kri[zcaron]an-Hergouth V., Mueller-Premru M., Seme K., Woodford on behalf of the Slovenian ESBL Study Group N.

Objectives: The epidemiology of extended-spectrum b-lactamases (ESBLs) has changed dramatically, with the emergence of CTX-M enzymes. They have accumulated rapidly in Escherichia coli, including those from the community. Less has been reported on the spread of CTX-M ESBLs in K. pneumoniae though evidence suggests they are replacing TEM/SHV ESBLs, e.g. in the UK. We investigate the emergence and epidemiology of CTX-M ESBLs in K. pneumoniae in Slovenian hospitals.

Methods: From January 2005 to May 2006, isolates of ESBL-producing K. pneumoniae causing nosocomial infections and/or colonisation were collected at 11 hospitals in Slovenia (one isolate per patient). ESBL production was detected by double-disc synergy tests and ESBL Etests. MICs were determined and interpreted according to CLSI criteria. Isolates were screened for blaCTX-M genes using multiplex PCR and were compared by PFGE of XbaI-digested genomic DNA. Data were analysed using BioNumerics software.

Results: A total of 177 ESBL-producing K. pneumoniae isolates were collected. Of these, 60 (33.9%), from 8 hospitals, were positive for blaCTX-M, all with group-1 enzymes. Clonal relationships among these 60 isolates were studied in comparison with 27 CTX-M-negative strains from the same hospitals. The isolates represented multiple strains, but several clusters of related isolates (>80% similarity) were observed, some of them including isolates from more than one centre. The largest cluster consisted of 26 clonally-related isolates with group-1 CTX-M enzymes, 24 of them from one hospital. This outbreak needs further investigation. Two isolates of this outbreak strain were identified in further hospitals, suggesting inter-site transmission. Most isolates had substantial resistance to both cefotaxime (>128 mg/L) and ceftazidime (>16 mg/L), possibly indicating CTX-M-15.

Conclusion:K. pneumoniae with CTX-M enzymes are an emerging problem in Slovenian hospitals, but currently represent a minority of ESBL producers of this species. This contrasts with the dominance of CTX-M enzymes among ESBL-producing E. coli in most European countries. The epidemiology of K. pneumoniae with CTX-M enzymes was complex, with the spread of several strains within and between hospitals. Since K. pneumoniae is an important hospital pathogen this worrying development merits closer monitoring.