title: Evaluation of the in vitro activity of fosfomycin tromethamine against Gram-negative bacterial strains recovered from community- and hospital-acquired urinary tract infections in Turkey.
abstract: OBJECTIVE
  The aim of this study was to evaluate the in vitro activities of antimicrobial agents including fosfomycin tromethamine against Gram-negative isolates recovered from urine samples.
  
  
  METHODS
  A total of 2334 strains (1562 Escherichia coli, 509 Klebsiella spp, 85 Proteus spp, 75 Pseudomonas spp, 45 Enterobacter spp, 37 Acinetobacter baumannii, 8 Citrobacter spp, 7 Morganella morganii, and 6 Serratia spp) were identified by VITEK 2 during the study period, November 2008 to June 2012. Antimicrobial susceptibilities of the strains were also evaluated using the Kirby-Bauer disk diffusion method, in accordance with the Clinical and Laboratory Standards Institute guidelines.
  
  
  RESULTS
  Overall, 2160 (92.5%) of the isolates tested were susceptible to fosfomycin tromethamine. Higher resistance rates were observed among inpatients compared to outpatients. Resistance rates by strain were: 2.0% for E. coli, 4.4% for Enterobacter spp, 6.9% for Klebsiella spp, 9.4% for Proteus spp, 48.6% for A. baumannii, 56.0% for Pseudomonas spp, and 100% for Morganella morganii. All Serratia spp and Citrobacter spp strains were susceptible. Extended-spectrum beta-lactamase (ESBL)-producing isolates displayed higher fosfomycin resistance rates than negative strains (19.2% vs. 2.9%). The highest in vitro activity was detected for amikacin, piperacillin-tazobactam, and imipenem for all strains including ESBL-producers.
  
  
  CONCLUSIONS
  Regardless of ESBL production, the excellent activity of fosfomycin against E. coli, Enterobacter spp, Serratia spp, and Citrobacter spp, indicates that the drug is a valuable therapeutic option for urinary tract infections, even those with co-trimoxazole- and ciprofloxacin-resistant isolates, but not in ESBL-producing Klebsiella spp, Pseudomonas spp, A. baumannii, and Proteus spp. Further studies should be carried out to determine the in vivo drug activity among Enterobacteriaceae other than E. coli.
authors.affiliation: Ahi Evran University, Research and Training Hospital, Clinical Microbiology Department, 40100 Kırşehir, Turkey. Electronic address: drtulin@yahoo.com.
authors.forename: Tulin
authors.initials: T
authors.lastname: Demir
authors.forename: Tuncay
authors.initials: T
authors.lastname: Buyukguclu
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017714:Community-Acquired Infections / Q000382:microbiology; D003428:Cross Infection / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D005578:Fosfomycin / Q000494:pharmacology*; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D014552:Urinary Tract Infections / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D005578:Fosfomycin
keywords: Antimicrobial resistance; Fosfomycin tromethamine; Urinary tract infections