title: Antimicrobial susceptibility pattern of extended-spectrum β-lactamase-producing bacteria causing nosocomial urinary tract infections in an Iranian referral teaching hospital.
abstract: OBJECTIVE
  Gram-negative bacilli are the most important cause of nosocomial urinary tract infections (UTIs). The production of extended-spectrum β-lactamase (ESBL) enzymes is a common mechanism of resistance among these bacteria. The aim of this study was to determine the rate of ESBL producing Gram-negative bacteria causing nosocomial UTI in a referral hospital as well as their susceptibility pattern to the most commonly used antibiotics.
  
  
  METHODS
  In a prospective cross-sectional study performed over a 6-month period, urinary specimens obtained from hospitalized patients with documented culture-proved nosocomial UTI (age range of 1-87 years). Isolated aerobic Gram-negative bacteria underwent further microbiologic tests for detection of ESBL, as well as antimicrobial susceptibility test using Kirby-Bauer (disk diffusion) and E-test methods.
  
  
  RESULTS
  During the study period, 213 urine samples were detected to have growth of Gram-negative organism. Escherichia coli was the most frequently isolated organism (61%). ESBL was detected in 102 isolates including 38.5% of E. coli, 39.5% of Klebsiella pneumonia, 88.5% of Pseudomonas aeruginosa, and 100% of Acinetobacter baumannii strains. Imipenem and meropenem were the most effective antibiotics on E. coli and K. pneumoniae strains. P. aeruginosa and A. baumannii strains showed high resistance to all tested antibiotics.
  
  
  CONCLUSIONS
  Large numbers of Gram-negative bacteria causing nosocomial UTIs produce ESBL with most being multidrug-resistant. Therefore, routine ESBL detection testing and subsequent antibiogram with disk diffusion method could be useful to determine the best treatment options for UTI.
authors.affiliation: Department of Clinical Pharmacy and Pharmacy Practice, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Rasool
authors.initials: R
authors.lastname: Soltani
authors.affiliation: Department of Clinical Pharmacy and Pharmacy Practice, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Ehsanpoor
authors.affiliation: Department of Infectious Diseases, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Farzin
authors.initials: F
authors.lastname: Khorvash
authors.affiliation: Nosocomial Infection Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Dariush
authors.initials: D
authors.lastname: Shokri
keywords: Antimicrobial; Gram-negative; extended-spectrum β-lactamase-producing bacteria; nosocomial urinary tract infection; susceptibility