Long-term resistance trends of uropathogens and association with antimicrobial prophylaxis

The aim of this study was to identify long-term resistance trends of uropathogens and determine the effect of prophylaxis in a pediatric patient population. A total of 638 uropathogens were isolated from urine samples collected from children hospitalized for urinary tract infection during the 12-year study period (1997-2008) and analyzed. The most frequent uropathogen identified was Escherichia coli (69 %), followed by Klebsiella spp. (9.7 %), Pseudomonas aeruginosa (6.7 %), Enterococcus spp. (5.6 %), and Proteus spp. (4.4 %). High resistance rates were observed for common agents used for empiric treatment, such as amoxicillin, cotrimoxazole, and ceftriaxone. Resistance increased over time for nitrofurantoin, ceftriaxone, and piperacilin-tazobactam (chi-square for trend p < 0.0002, p < 0.0034 and p < 0.014, respectively) and decreased for cefuroxime (p < 0.016) and gentamicin (p < 0.014). The use of prophylaxis was related to an increased proportion of non-E. coli pathogens (46.9 vs. 26.9 %; odds ratio 2.4, 95 % confidence interval 1.61-3.55; p < 0.0001), as well as to increased resistance of non-E. coli pathogens, and was a major risk factor associated with resistance to amoxiclav (p < 0.005), cotrimoxazole (p < 0.0001), cefuroxime (p < 0.0001), ceftriaxone (p < 0.0001), gentamicin (p < 0.0001), and nitrofurantoin (p < 0.0001). Our findings point to considerable changes in the long-term resistance patterns of uropathogens and an association of prophylaxis with resistance. Our results suggest the need for continuous surveillance, re-evaluation of empiric regimens and further assessment of the role of prophylaxis in the treatment of urinary tract infection.