Investigation of a possible nosocomial urinary tract infection outbreak due to ESBLS producing E. coli

Abstract number: 1135_86

Kanellopoulou M., Giakkoupi P., Skarmoutsou N., Karakatsani S., Adamou D., Koratzanis G., Vatopoulos A.C., Papafrangas E.

Aim:  

Multiresistant E. coli are very rare in our hospital. Thus the isolation of four E. coli isolates showing the same multiresistant resistance phenotype from the urine of four patients hospitalized in the same ward during a week period (14/06/2004–21/06/2004) urged us to investigate the possible epidemiological significance of this finding.

Material and Patients:  

The E. coli strains were isolated from equal number of inpatients, two men and two women, mean aged 75 years old who were hospitalized for infections other than UTI (n : 3) and immunosuppression (n : 1). All but one had pyuria (>50 leucocytes p. f), fever (>38°C) and were receiving extended spectrum antibiotics. Indwelling catheters were present in all four patients.

Methods:  

The resistance phenotype was performed by Kirby Bauer and microdilution methods according to NCCLS guidelines. ESBLS production was confirmed by Double Disk Test (DDT) and E-test : cefepime/cefepime–clavulanic (AB BIODISK, Solna, Sweden). Biotyping was based on Wider II (Francisco SORIA Melguizo, SA) automated system results. The ERIC II PCR was used for the molecular typing of the isolates.

Results:  

Although epidemiological data (time and space clustering) as well as phenotypic data (all strains showed the same resistant phenotype and the same biotype) were consistent with possible clonal spread of the same isolate in all patients, molecular typing revealed that only two out of the four E. coli ESBLS producing strains (isolated from patients who shared the same room) were similar and thus could be associated as part of the same outbreak. The remaining two strains had different molecular patterns.

Conclusion:  

This study supports the clue that classic microbiological studies (colonial morphology, biotype and resistance phenotype) as well as molecular typing methods are both necessary and must be performed to investigate and reveal an outbreak of infection in a hospital setting.