Sensitivities of Cefixime, Ceftriaxone and Sulfamethoxazole/Trimethoprim in SPICE-HaM-Associated Urinary Tract Infections in Children

Background/Objectives: Third-generation cephalosporins are used to treat many infections, including urinary tract infections. Despite the risk of inducing resistance in SPICE-HaM microorganisms (Serratia, Providencia, indole-positive Proteus, Citrobacter freundii complex, Enterobacter cloacae complex, Klebsiella aerogenes, Hafnia alvei and Morganella morganii), a group of microorganisms with inducible beta-lactamase potentials, guidelines still recommend treating uncomplicated cystitis with third-generation cephalosporins. To improve outpatient pediatric antimicrobial practice, this study aimed to develop a five-year pediatric cumulative antimicrobial susceptibility testing report for SPICE-HaM microorganisms in urine and compare the in vitro sensitivity of cefixime/ceftriaxone with sulfamethoxazole/trimethoprim. Methods: Over 300 pediatric SPICE-HaM urine isolates, processed at regional microbiology laboratories of LifeLabs British Columbia between 2020 and 2024, were analyzed. Results: Compared to cefixime, sulfamethoxazole/trimethoprim demonstrated higher sensitivity against Citrobacter freundii complex (65% versus 95%, p < 0.05, n = 57), Enterobacter cloacae complex (49% versus 92%, p < 0.05, n = 89), and Morganella morganii (68% versus 92%, p < 0.05, n = 76). Compared to ceftriaxone, sulfamethoxazole/trimethoprim failed to show significantly different sensitivities for the SPICE-HaM microorganisms. Conclusions: Sulfamethoxazole/trimethoprim is possibly a more favourable oral agent for SPICE-HaM-associated urinary tract infections in the local pediatric community population compared to cefixime, a third-generation cephalosporin. However, compared to ceftriaxone, sulfamethoxazole/trimethoprim appears to have similar efficacy for SPICE-HaM-associated urinary tract infections.