Characteristics of urinary tract infection pathogens and their in vitro susceptibility to antimicrobial agents in China: data from a multicenter study

OBJECTIVE: This study assessed the characteristics of pathogens identified in clinical isolates from patients with urinary tract infection (UTI) and their in vitro sensitivity to commonly used antibiotics in the clinical setting in China. DESIGN AND SETTING: Multicenter study was conducted between January and December 2011 in 12 hospitals in China. PARTICIPANTS: Urine samples were collected from 356 symptomatic patients treated in the study hospitals for acute uncomplicated cystitis, recurrent UTI or complicated UTI. PRIMARY AND SECONDARY OUTCOME MEASURES: Minimal inhibitory concentrations (MICs) were measured using broth microdilution according to the Clinical and Laboratory Standards Institute 2011 guidelines. Thirteen antimicrobial agents were tested: fosfomycin tromethamine, levofloxacin, moxifloxacin, cefdinir, cefixime, cefaclor, cefprozil, cefuroxime, amoxicillin/clavulanic acid, cefotaxime, azithromycin, nitrofurantoin and oxacillin. Escherichia coli isolates were screened and extended spectrum β-lactamases (ESBL) production was confirmed by a double-disk synergy test. RESULTS: 198 urine samples were culture-positive and 175 isolates were included in the final analysis. E coli was detected in 50% of cultures, followed by Staphylococcus epidermidis (9%), Enterococcus faecalis (9%) and Klebsiella pneumoniae (5%). The detection rate of ESBL-producing E coli was 53%. Resistance to levofloxacin was the most common among all the isolates. Nitrofurantoin and fosfomycin tromethamine had the greatest activity against E coli; overall, 92% and 91% of isolates were susceptible to these antimicrobials. E faecalis had the highest susceptibility rates to fosfomycin tromethamine (100%). CONCLUSIONS: The most frequently identified pathogens in our patients were ESBL-producing E coli and E faecalis. Fosfomycin tromethamine and nitrofurantoin showed a good antimicrobial activity against UTI pathogens. They may represent good options for the empiric treatment of patients with UTI.