Survey of the susceptibility of urinary isolates to antibacterial agents in 2003

In 2003, 826 uropathogenic strains were obtained from the urine of our patients. We assessed their activities to antibacterial agents based on the minimal inhibitory concentration (MIC) breakpoints recommended by the National Committee for Clinical Standards (NCCLS). Methicillin-resistant strains accounted for about 70% of Staphylococcus aureus and Staphylococcus epidermidis. The most common gram-positive species was Enterococcus faecalis (15.6%). Enterococcus faecium was the most resistant of the enterococcal species, and the rate of susceptibility to β-lactams (BLs), fluoroquinolones (FQs), and tetracyclines (TCs) was 0%, 6%, and less than 18%, respectively. Escherichia coli accounted for over 50% of the gram-negative bacilli. The proportion of FQ-resistant or intermediate strains was over 20%, and four of these strains (1.1%) were suspected of producing extended-spectrum β-lactamase (ESBL). All the ESBL-producing strains (ESBLs) possess resistance to FQs. Over 95% of Klebsiella pneumoniae was susceptible to all agents. The distribution of antimicrobial activity against Pseudomonas aeruginosa indicated a decrease in the number of multidrug-resistant strains and an increase in strains susceptible to all agents. Some differences existed in the resistance to antibacterial agents among Proteus species. No ESBL-producing or multidrug-resistant strain was isolated from Serratia marcescens. This survey suggests that serious clinical problems will result from the increasing number of enterococcal species with multidrug resistance in gram-positive cocci, and isolates of ESBL-producing or FQs-resistant strains in gram-negative bacilli.