Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae: In vitro Susceptibility to Fosfomycin, Nitrofurantoin and Tigecycline

Objective: To assess the susceptibility trends of community-acquired extended-spectrum beta-lactamase (ESBL)-producing urinary isolates with particular reference to fosfomycin, nitrofurantoin and tigecycline. Materials and Methods: Seven hospitals across the United Arab Emirates participated in this study from June 2008 to March 2010. The antibiotic sensitivity of ESBL-producing uropathogens to a panel of antibiotics including tigecycline, fosfomycin and nitrofurantoin was assessed. The Hyplex ESBL identification system (h-ES-ID) was used for genotypic identification. Results: Two hundred and ninety-two ESBL-producing Enterobacteriaceae isolates were identified during the study period. Of these, 182 (62%) were urinary isolates and comprised of Escherichia coli : 149 (81.9%), Klebsiella pneumoniae : 30 (16.5%) and Proteus mirabilis : 3 (1.6%). Of the 182 urinary isolates, 179 (98.3%) were from patients with community onset urinary tract infections. The h-ES-ID system identified 172 (94.5%) of the urinary isolates as CTX-M positive. All isolates were susceptible to imipenem and meropenem. Over half of the isolates showed resistance to gentamicin (98; 53.8%), trime-thoprimsulfamethoxazole (139; 76.4%) and ciprofloxacin (143; 78.6%). Sensitivity to nitrofurantoin and fosfomycin was 90 and 100%, respectively. Two CTX-M-positive K. pneumoniae isolates with tigecycline resistance (MIC >4 mu g/ml) were identified. Conclusion: There is dissemination of CTX-M ESBL-producing urinary pathogens into the community. Fosfomycin and nitrofurantoin were active against ESBL-positive uropathogens, and emergence of tigecycline resistance needs close monitoring. Copyright (C) 2012 S. Karger AG, Basel