Association between cephalexin dosing frequency in uncomplicated urinary tract infections and treatment failure in discharged Emergency Department patients Kameron Francis, Rachel Musgrove, Analise Williams, Fataba Gailor, Meghan Hammond, Devon Burhoe Background/Purpose: Urinary tract infections (UTI) are among the most common bacterial infections seen in the health care system. Cephalexin, commonly prescribed for UTI, has no standardized dosing frequency indicative of superiority. Cephalexin can be prescribed twice daily, three times daily, or four times daily. This study aims to assess treatment failure with various cephalexin dosing frequencies in the treatment of UTI. Methodology: A multicenter, retrospective, observational cohort study which collects eligible patients via ICD-10 codes. Eligible patients are those > 18 with documented diagnosis of acute cystitis or uncomplicated UTI with a positive urine culture with susceptibility to cefazolin. Patient must be prescribed cephalexin two, three, or four times daily for five to seven days. Exclusion criteria include complicated or recurrent UTI requiring prophylactic antibiotics, patients without cultures preformed or requiring renally adjusted cephalexin. Treatment failure within 30 days defined as patients who: return symptomatic to the emergence department (ED), present with signs and symptoms of urinary tract infection after initiation of cephalexin treatment seeking medical attention outside of the ED, or required an antibiotic change after the initiation of a 5–7-day course of cephalexin. Results: 131 patients were included in the study with over 80% of the subjects being female. The subjects were evenly distributed between three dosing strategy groups. 14 subjects (10.7%) had treatment failure occur after receiving their initial cephalexin course (p-value 0.984). Patients most often failed treatment due to returning to the emergency department symptomatic after the initial cephalexin treatment. The average time to treatment failure was 22 days. Six subjects required a change in antibiotic regimen, and half of these subjects received cephalexin twice daily initially. The most common alternative antimicrobial regimen was vancomycin with piperacillin/tazobactam due to the development of urosepsis. There was no incidence of bacterial resistance in any of the 131 subjects. Conclusions: There was no difference between the rate of treatment failure and the three different dosing strategies for cephalexin in uncomplicated urinary tract infections. Among the fourteen patients that failed therapy, most often it was due to returning to the emergency department symptomatic within 30 days of initial treatment. There were higher rates of an alternative antimicrobial therapy needed due to urosepsis in the twice daily group. Overall, our data aligns with current data which shows no association between treatment failure and dosing strategy in uncomplicated urinary tract infections.
