Antimicrobial Susceptibility and Frequency of Extended Spectrum Beta-Lactamase (ESBL) of Escherichia coli Strains Isolated from Community Acquired and Nosocomial Infections

Abstract

Introduction: Escherichia coli is one of the most important causes of nosocomial and community acquired infections. Beta-lactam antibiotics constitute one of the major therapeutic options to treat infections caused by these microorganism. Resistance to beta-lactams antibiotics is mainly caused by extended-spectrum beta-lactamases (ESBLs). The aim of this study was to determine the production rates of ESBL of E. coli isolates causing nosocomial and community acquired infections as well as to determine their antimicrobial susceptibility patterns. Materials and Methods: Between June 2006-December 2010, 555 E. coli strains isolated from clinical specimens (256 wound, 213 urine, 42 blood, 28 respiratory truct, 16 others) of inpatients, and 3052 E. coli strains isolated from urines of outpatients admitted to Cumhuriyet University Research and Training Hospital, were included to the study. Identification of the isolates and antibiotic susceptibility testings were performed by an automatic system (BD, Phoenix, USA). The production of ESBL was done by the broth microdilution method according to Clinical and Laboratory Standards Institute guidelines. Results: The rate of ESBL producers in the nosocomial isolates was approximately three times higher than the community acquired isolates (47.7% vs. 15.8%). Ciprofloxacin and piperacillin-tazobactam resistance rate were significantly different between the nosocomial and community acquired ESBL producing E. coli isolates. Ciprofloxacin resistance was higher in community acquired strains (84.3% vs. 77.7%, p= 0.026) and piperacillin-tazobactam resistance was higher in nosocomial strains (44.5% vs. 37.1%, p= 0.046). Nitrofurantoin and fosfomycine resistance in the community acquired ESBL positive E. coli strains was quite low (4.0% vs. 0.5%), and the nosocomial isolates were not studied. All nosocomial and community acquired E. coli isolates were sensitive to carbapenems. Conclusion: These results show that ESBL production is high in nosocomial E. coli isolates, and some differences can be seen in antibiotics susceptibility of nosocomial and community acquired ESBL producing E. coli strains.

Keywords

• Escherichia coli
• ESBL
• Antimicrobial susceptibility
• Nosocomial infection
• Community acquired infection