Frequency and antibiotic susceptibility of extended-spectrum b-lactamase producing Enterobacteriaceae isolated from urinary tract infections in a two-year period

Abstract number: P2083

Skandami-Epitropaki V., Tsiringa A., Xanthaki A., Arida P., Dimitriou V., Toutouza M.

Objectives: To study the isolation frequency and antibiotic susceptibility of ESBL-producing enterobacteriaceae strains isolated from hospitalised and community patients with urinary tract infections (UTI).

Methods: During a two-year period (2006–2007), 976 strains of Escherichia coli and 142 strains of Klebsiella pneumoniae were isolated from midstream urine samples in our microbiology laboratory. Identification to the species level was performed with the VITEK TWO system (Bio-Merieux) and susceptibility to antimicrobial agents was tested by the disk diffusion method according to CLSI recommendations. Detection of ESBL expression was performed by two methods, the double-disk synergy (DDS) test and the VITEK TWO card MIC/AST for ESBL. From the strains tested, 696 (584 E. coli and 112 K. pneumoniae) were isolated from hospitalised patients and 422 (392 E. coli and 30 K. pneumoniae) from community patients with UTI.

Results: ESBL production was determined in 51 out of 1118 strains of Enterobacteriaceae (4.6%). The ESBL phenotype was detected in 3.4% (33 out of 976) strains of E. coli and 12.7% (18 out of 142 strains) of K. pneumoniae urine isolates. For E. coli, ESBL production was detected in 30 out of 584 strains isolated from hospitalised patients (5.1%) and 3 out of 392 patients of the community (0.8%). For K. pneumoniae, ESBL production was detected in 15 out of 112 strains from hospitalised patients (13.4%) and 3 out of 30 strains from community patients (10.0%). The antibiotic susceptibility rates for the ESBL-producing strains were for E. coli and K. pneumoniae respectively: imipenem 100%-100%, gentamicin 57.6%-66.7%, amikacin 78.8%-38.9%, netilmicin 69.7%-44.4%, tobramycin 48.5%-11.1%, chloramphenicol 57.6%-44.4%, ciprofloxacin 24.2%-11.1%, norfloxacin 24.2%-11.1%, tetracycline 18.2%-50.0%, trimethoprim/sulfamethoxazole 24.2%-5.6%. ESBL production and fluoroquinolone resistance was detected in 25 out of 33 (75.8%) strains of E. coli and 16 out of 18 (88.9%) strains of K. pneumoniae.

Conclusions: ESBL-producing bacteria are becoming an increasing therapeutic problem not only in hospitalised but also in community patients. High resistance rates to quinolones were observed among these strains, but carbapenems had a good activity. Monitoring of ESBL production and antibiotic susceptibility testing are necessary to avoid treatment failure in patients with urinary tract infections.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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