Predicting Antibiotic Susceptibility Among Patients With Recurrent Urinary Tract Infection Using a Prior Culture

PURPOSE

Recurrent cystitis guidelines recommend relying on a local antibiogram or prior urine culture to guide empirical prescribing, yet little data exist to quantify the predictive value of a prior culture. We constructed a urinary antibiogram and evaluated test metrics (sensitivity, specificity, and Bayes' positive and negative predictive values) of a prior gram-negative organism on predicting subsequent resistance or susceptibility among patients with uncomplicated, recurrent cystitis.

MATERIALS AND METHODS

We performed a retrospective database study of adults with recurrent, uncomplicated cystitis (cystitis occurring 2 times in 6 months or 3 times in 12 months) from urology or primary care clinics between November 1, 2016, and December 31, 2018. We excluded pregnant females, patients with complicated cystitis, or pyelonephritis. Test metrics were calculated between sequential, paired cultures using standard formulas.

RESULTS

We included 597 visits from 232 unique patients wherein 310 (51.2%) visits had a urine culture and 165 had gram-negative uropathogens isolated. Patients with gram-negative uropathogens were mostly females (97%), with a median age of 58.5 years. Our antibiogram found 38.0%, 27.9%, and 5.5% of Escherichia coli isolates had resistance to trimethoprim-sulfamethoxazole, ciprofloxacin, and nitrofurantoin, respectively. Prior cultures (within 2 years) had good predictive value for detecting future susceptibility to first-line agents nitrofurantoin (0.85) and trimethoprim-sulfamethoxazole (0.78) and excellent predictive values (≥0.90) for cefepime, ceftriaxone, cefuroxime, ciprofloxacin, levofloxacin, gentamicin, tobramycin, piperacillin-tazobactam, and imipenem.

CONCLUSIONS

Considerable antibiotic resistance was detected among E coli isolates in patients with recurrent, uncomplicated cystitis. Using a prior culture as a guide can enhance the probability of selecting an effective empirical agent.

Efficacy data of halogenated phenazine and quinoline agents and an NH125 analogue to veterinary mycoplasmas

BACKGROUND

Mycoplasmas primarily cause respiratory or urogenital tract infections impacting avian, bovine, canine, caprine, murine, and reptilian hosts. In animal husbandry, mycoplasmas cause reduced feed-conversion, decreased egg production, arthritis, hypogalactia or agalactia, increased condemnations, culling, and mortality in some cases. Antibiotics reduce transmission and mitigate clinical signs; however, concerning levels of antibiotic resistance in Mycoplasma gallisepticum and M. capricolum isolates exist. To address these issues, we evaluated the minimum inhibitory concentrations (MICs) of halogenated phenazine and quinoline compounds, an N-arylated NH125 analogue, and triclosan against six representative veterinary mycoplasmas via microbroth or agar dilution methods. Thereafter, we evaluated the minimum bactericidal concentration (MBC) of efficacious drugs.

RESULTS

We identified several compounds with MICs ≤25 μM against M. pulmonis (n = 5), M. capricolum (n = 4), M. gallisepticum (n = 3), M. alligatoris (n = 3), M. agassizii (n = 2), and M. canis (n = 1). An N-arylated NH125 analogue, compound 21, served as the most efficacious, having a MIC ≤25 μM against all mycoplasmas tested, followed by two quinolines, nitroxoline (compound 12) and compound 20, which were effective against four and three mycoplasma type strains, respectively. Nitroxoline exhibited bactericidal activity among all susceptible mycoplasmas, and compound 21 exhibited bactericidal activity when the MBC was able to be determined.

CONCLUSIONS

These findings highlight a number of promising agents from novel drug classes with potential applications to treat veterinary mycoplasma infections and present the opportunity to evaluate preliminary pharmacokinetic indices using M. pulmonis in rodents as an animal model of human infection.