Antibiotic susceptibility of enterobacteriaceae strains isolated from urinary tract infections

Abstract

Enterobacteriaceae are the most frequent causes of urinary tract infections. We analysed the antibiotic susceptibility of urinary isolates recovered at the Microbiology Laboratory of Mures County Emergency Clinical Hospital.

Materials and methods: We collected data from the electronic data base of the laboratory. All successive non-duplicate, clinically significant Enterobacteriaceae strains tested during a one year period (2015) were included in our study. Recurrent isolates were considered for analysis only if there were phenotypically different. Pluribacterial samples were excluded from the study.

Results: A total of 672 strains from 651 patients were involved in our study. The most frequent was E. coli (n=500, 74%), followed by Klebsiella pneumoniae (90, 13%), Proteus mirabilis (34, 5%), Serratia marcescens (18, 3%) and others (5%). The highest susceptibility was registered for ertapenem (93%). The least active antibiotic was ampicillin (31%). Relatively low susceptibility was detected against fluoroquinolons (64%) and trimethoprim-sulfamethoxazol (60%). In case of E. coli the highest susceptibility was registered for ertapenem (99.8%) and nitrofurantoin (99%). In case of Klebsiella pneumoniae the most active antibiotic was ertapenem (78%).

Conclusions: The antibiotic most active against all urinary Enterobacteriaceae isolates was ertapenem. Antibiotics commonly used to treat urinary tract infections, such as fluoroquinolons and trimethoprim sulfamethoxazol were less efficient, therefore their empirical use should be avoided. Nitrofurantoin, an antibiotic used to treat uncomplicated urinary tract infections caused by E. coli, was highly active.