A study of the 20-year evolution of antimicrobial resistance patterns of pediatric urinary tract infections in a single center.

Febrile urinary tract infections (UTIs) are important bacterial infections in children but increasingly difficult to treat due to antimicrobial resistance. We performed a retrospective analysis of the prevalence of uropathogens in hospitalized children with a febrile UTI between 2000 and 2019 in our university hospital to get more insight into trend and determinants of antimicrobial resistance over time. There were 1010 hospitalizations in children with a median age of 1.1 years. Thirty-six percent had an abnormal ultrasound and/or the presence of vesico-ureteral reflux, defined as CAKUT. Escherichia coli was the most prevalent pathogen (76%). However, there was an increasing prevalence towards other gram-negative organisms over time, and these pathogens were more common in children with congenital anomalies of kidney and urinary tract (CAKUT) (OR 4.26 (3.14-5.78), p < 0.001). E. coli strains demonstrated an increase in resistance against amoxicillin clavulanic acid (AMC) over time from 16% (2000-2004) to 36% (2015-2019) with an average increase of 2.0%/year; this was + 1.1%/year for third-generation cephalosporin. Multivariate analysis demonstrated that prior antibiotic use was an additional risk factor for antimicrobial resistance in E. coli. Nevertheless, increasing resistance was also observed in children without reported previous antibiotic treatment (+ 1.9%/year, p = 0.04).    Conclusion: We observed a significant pattern of increasing antimicrobial resistance of E. coli within a relatively short period of time, making it increasingly difficult to treat pediatric UTIs. This pattern was also seen in children without underlying risk factors (recent antibiotic treatment or structural urological disease). This is indicative for a larger problem in the general population and an important threat to our current standard of health care. What is Known: • Escherichia coli is the most frequent pathogen in pediatric urinary tract infections. • There is an increasing antimicrobial resistance against commonly used antibiotics in urinary tract infections. What is New: • The first 20-year retrospective, longitudinal study on characteristics of the microorganisms of pediatric urinary tract infections in a single center. • A 1-2% yearly increase in antimicrobial resistance, not only in children with congenital anomalies of the kidneys or recent antibiotic treatment but also in children without risk factors.