Drug susceptibility and treatment response of common urinary tract infection pathogens in children.

BACKGROUND/PURPOSE To document the trends of sensitivity and to find whether it is necessary to change antibiotics in selected patients according to the sensitivity test results in our clinical practice. METHODS We collected urine culture results from 0-18-year-old patients in the National Taiwan University Hospital from January 1, 2003 to October 31, 2012. Their medical chart was reviewed to identify true pathogens responsible for their urinary tract infection (UTI). We checked the percentage of susceptibility of these pathogens to ampicillin, amoxicillin-clavulanate (AMC), cefazolin, cefmetazole, ceftriaxone, gentamicin, and trimethoprim-sulfamethoxazole (TMP-SMX) according to the Clinical and Laboratory Standards Institute (CLSI) guideline. The extended-spectrum-beta-lactamases (ESBLs) rate was also checked. In addition, we reviewed the treatment response of different antibiotics. Defervescence within 48 hours after initial antibiotics use was considered responsive. RESULTS A total of 7758 urine cultures positive for Escherichia coli infection were collected during the 10-year period. The E. coli cefazolin susceptibility rate was 62-73% during 2003-2010, but it dropped to 23% in 2011 and 28% in 2012 after the new CLSI guideline (M100-S21) was released. However, other antibiotics did not show a significant difference. In UTI caused by E. coli, on average, the sensitivity rates for various antibiotics were as follows: cefmetazole, 90%; ceftriaxone, 85%; gentamicin, 77%; AMC, 61%; TMP-SMX, 47%; and ampicillin, 20%. The ESBL rate was also found to increase (2-11%; p < 0.01). The overall response rate of UTI caused by E. coli to first-line antibiotics such as first-generation cephalosporin and/or gentamicin was 78%. CONCLUSION The susceptibility of common urinary tract pathogens to cefazolin has decreased dramatically since 2010. This trend may be due to the change in the CLSI guideline. Although the susceptibility rate to first-line empirical antibiotics shows a decreasing trend, we found that the clinical response was acceptable for our first-line empirical antibiotics.