Role of age and sex in determining antibiotic resistance in febrile urinary tract infections

Objectives To identify the age- and sex-specific antimicrobial susceptibility patterns of Gram-negative bacteria (GNB) in outpatient febrile urinary tract infections (UTIs) in Korea. Methods A total 2262 consecutive samples collected from patients aged 1–101 years with febrile UTIs, during the period January 2012 to December 2014, were analyzed in this multicentre, retrospective cohort study. Results The sensitivities to cefotaxime and cefoxitin were over 85% for females but under 75% for males. Sex played an important role in the susceptibility of GNB to cefotaxime (p < 0.001) and cefoxitin (p < 0.001). The sensitivity to ciprofloxacin (age >20 years) was under 75% in both sexes, and was not influenced by sex (p = 0.204). Age distributions of the incidences of resistance to cefotaxime, cefoxitin, and ciprofloxacin (age >20 years) were similar to the age distribution of the incidence of GNB, which indicates that the resistance patterns to these drugs were not affected by age (Kolmogorov–Smirnov test, female/male: p = 0.927/p = 0.509, p = 0.193/p = 0.911, and p = 0.077/p = 0.999, respectively). Conclusions Age is not a considerable factor in determining the antibiotic resistance in febrile UTIs. Ciprofloxacin should be withheld from both sexes until culture results indicate its use. Second- or third-generation cephalosporins such as cefoxitin and cefotaxime can be used empirically only in females.