A nosocomial outbreak of CTX-M-15 producing E. coli in Norway

Abstract number: 1134_01_33

Haldorsen B., Natås O., Grundt H., Bue B., Naseer U., Walsh T.R., Sundsfjord A.

Objective:  

The first nosocomial outbreak of ESBL-producing E. coli in Norway involving 8 elderly patients is described.

Material and methods:  

Four ESBL-producing E. coli strains were isolated from different patients at the Department of Pulmonary Medicine, Regional Hospital of Rogaland august 2004. Additional 4 urinary tract E. coli isolates with an ESBL production phenotype were detected during the following month from out-patients that had been hospitalised in the same department in august 2004. The patients were between 66 and 93 years; 6 men and 2 women. The 8 isolates were recovered from urine samples (N = 5), blood, sputum, lung and kidney tissue at autopsy. Antimicrobial susceptibilities were tested by Etest and agar disk diffusion and interpretation was according to the Norwegian Working Group for Antibiotics. Molecular typing was performed by TEM-, SHV, CTX-M, and ISEcp1 PCRs, sequence analysis of PCR amplicons and XbaI-PFGE.

Results:  

All strains expressed a typical ESBL-cefotaximase profile (cefotaxime MIC > ceftazidime MIC) and clavulanic acid synergy. Seven strains displayed high-level resistance towards all penicillins and cephalosporines, while one strain were susceptible to ceftazidime. Multiple resistances to other antimicrobial agents including gentamicin, nitrofurantoin, trimethoprim-sulfamethoxazole, ciprofloxacin and piperacillin-tazobactam were detected. All strains were susceptible to carbapenems. Molecular characterization revealed a CTX-M-15 in 6 strains, CTX-M-3 in one strain, and one strain to be analysed. The six CTX-M-15 strains had indistinguishable XbaI-PFGE patterns and positive ISEcp1-element PCRs consistent with a clonal relationship. Three of the patients died during this period and the potential impact of the actual infection is currently being assessed. Infection control measurements were implemented and additional ESBL-producing E. coli has not been recovered. Preliminary environmental samples and additional investigations have not discerned any apparent source for this outbreak

Conclusions:  

(i) The outbreak illustrates the epidemic potential of this particular multiple-antibiotic resistant CTX-M-15 producing E. coli strain also in a country with a low prevalence of antimicrobial resistance. (ii) The clonal relationship to epidemic CTX-M-15 producing E. coli strains in other countries has to be investigated to identify potential common reservoirs and lines of resistance transmission as a basis for intervention.