The third national Japanese antimicrobial susceptibility pattern surveillance program: Bacterial isolates from complicated urinary tract infection patients

The antimicrobial susceptibility patterns of bacterial pathogens isolated from patients with complicated urinary tract infections were analyzed using national surveillance data. The data consisted of 881 bacterial strains from eight clinically relevant species. The data were collected for the third national surveillance project from January 2015 to March 2016 by the Japanese Society of Chemotherapy, the Japanese Association for Infectious Disease, and the Japanese Society of Clinical Microbiology. Surveillance was undertaken with the cooperation of 41 medical institutions throughout Japan. Fluoroquinolone required a MIC₉₀ of 2–64 mg/L to inhibit the 325 Escherichia coli strains tested and the proportion of levofloxacin resistant E. coli strains increased to 38.5% from 29.6% in 2011 and 28.6% in 2008. The proportion of levofloxacin resistant strains of Pseudomonas aeruginosa and Enterococcus faecalis decreased from previous reports and the proportion of multidrug-resistant P. aeruginosa and carbapenem-resistant Enterobacteriaceae remained low. Among methicillin-resistant Staphylococcus aureus (MRSA) strains, strains with reduced susceptibility to vancomycin (minimum inhibitory concentration, 2 μg/mL) increased to 14.7% from 5.5%. Bacterial strains that produced extended-spectrum β-lactamase included E. coli (79 of 325 strains, 24.3%), Klebsiella pneumoniae (9 of 177 strains, 7.7%), and Proteus mirabilis (6 of 55 strains, 10.9%). The proportion of extended-spectrum β-lactamase producing E. coli and K. pneumoniae strains increased from previous surveillance reports.