Clinical Risk Scores May Help Facilitate Empiric Antibiotic Treatment for cUTI

Clinical risk scores may help facilitate appropriate empiric antibiotic treatment for adult outpatients with complicated urinary tract infection (cUTI), according to results of a study published in Open Forum Infectious Diseases.

Researchers performed a retrospective cohort study from December 2017 to December 2020 among adult Kaiser Permanente Southern California members with an outpatient cUTI. The researchers evaluated the use of clinical risk scores in adults with cUTI for predicting the likelihood of nonsusceptibility to commonly used antibiotics. Clinical data were used to develop separate clinical risk scores for trimethoprim-sulfamethoxazole (TMP-SMX), fluoroquinolone, nitrofurantoin, and third-generation cephalosporins (3-GC). Chi-squared and Fisher exact testing were used to compare the distribution of covariates between patients with susceptible vs nonsusceptible infections.

A total of 26,326 patients (median age, 65.0 [IQR, 47-77] years) were included in the study, representing 30,450 unique cUTI episodes. Among the patients, 54.4% were women, 41.6% were Hispanic, 23.6% were previously hospitalized, and 49.5% were previously admitted to the emergency department (ED).

The researchers identified 32,450 uropathogens across all cUTI episodes, of which 37.4% were nonsusceptible to TMP-SMX, and 20%, 27%, and 24% were non-susceptible to fluoroquinolones, nitrofurantoin, and 3-GC, respectively. Multidrug resistance was common, with nonsusceptibility to 1 or more antibiotics identified in 60.7% of cUTI episodes.

Further analysis was performed between patients with susceptible vs nonsusceptible cUTIs to determine covariates associated with nonsusceptibility. Patients with nonsusceptible infections were more likely to be older men with a greater number of comorbidities. In addition, higher numbers of prior antibiotics, cUTI recurrences, and prior hospitalizations and ED admissions were more common among patients with nonsusceptible infections.

For all 4 antibiotics, analysis of clinical risk scores showed that prior receipt of each individual antibiotic was the most significant predictor of nonsusceptibility. In regard to TMP-SMX, the risk for nonsusceptibility was higher than 20% in the absence of any significant risk factors. Owing to this finding, the researchers noted that the empiric use of TMP-SMX for adult outpatients with cUTI may not be appropriate.

Study limitations include the possibility that some predictors of nonsusceptibility were missed as only risk factors present at baseline were included in the analysis. Other limitations include the lack of data on prior colonization, prior resistant infections, urinalysis results, and physical examination findings.

According to the researchers, “Our risk scoring systems can help clinicians make more informed empirical antibiotic selection decisions that may minimize delays in the receipt of appropriate therapy and reduce adverse outcomes in adult outpatients with cUTIs.”

Disclosure: This research was supported by Spero Therapeutics, and multiple study authors declared affiliations pharmaceutical, biotech, and/or device companies. Please see the original reference for a full list of disclosures.