Less Treatment Failures Seen With Empiric Cephalexin in Pediatric UTI

SAN DIEGO, CA—For treatment of uncomplicated, outpatient urinary tract infection (UTI), fewer failures were seen with empiric cephalexin than with trimethoprim/sulfamethoxazole (TMP-SMX) or amoxicillin, researchers presented at IDWeek 2015.

Jonathan M. Beus, MD, MS, from The Children's Hospital of Philadelphia, Philadelphia, PA, described the institution's recommendation, in June 2011, of cephalexin as first-line therapy for uncomplicated outpatient UTI. This recommendation was based on review of susceptibility to other 1st generation cephalosporins.

In this retrospective cohort study, Dr. Beus and his team sought to determine the risk of treatment failure in children with UTI receiving empiric cephalexin due to a lack of interpretive guidelines for direct susceptibility to cephalexin in the Clinical and Laboratory Standards Institute (CLSI).

The study included children aged 2 months–11 years who presented to 1 of 27 pediatric primary care practices of the Emergency Department from January 2005–September 2013 with a positive urine culture (>100K CFU if clean-catch or >50K CFU if catheterized), pyuria, and signs/symptoms consistent with UTI (eg, fever, dysuria, abdominal or flank pain, urgency, or frequency). In children ≤2 years old, signs/symptoms included feeding difficulties, fussiness, or vomiting. Children with comorbid conditions, urologic abnormalities, UTI prophylaxis, or immunosuppression were excluded.

Study authors' analysis accounted for age, gender, race, insurance type, and practice type.

A total of 761 patients received empiric cephalexin; 1,010 received TMP-SMX; and 373 received amoxicillin. Treatment failure, defined as a switch to an alternate antibiotic within 15 days of urine culture, occurred in 12.6% of cephalexin patients, 18.7% of TMP-SMX patients, 35.8% of amoxicillin patients, 24.1% of amoxicillin-clavulanate, 11.7% of cefdinir patients, and 16% of cefixime patients. The adjusted odds ratio for treatment failure comparing cephalexin to TMP-SMX was 0.67 (95% CI: 0.49–0.89).

Treatment success was seen in 92% of cephalexin-treated patients who had a pathogen susceptible to cefazolin or cephalothin, similar to that observed in the TMP-SMX treated patients, 92.5%.

Susceptibility to other first-generation cephalosporins implied a high probability of clinical success for cephalexin, Dr. Beus and colleagues noted. However, “due to the limitations of a retrospective study, we were unable to assess the converse, that resistance to other first-generation cephalosporins was associated with a high probability of clinical failure for cephalexin.”

They concluded that “the generalizability of these results to other practices is dependent on similar patterns of antimicrobial resistance.”

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