Antimicrobial susceptibility patterns from urinary isolates obtained from cats (2013-2020)

Abstract

Background: Bacterial urinary tract infections have been associated with comorbidities and increased antimicrobial resistance over time.

Objective: To identify bacterial species, antimicrobial susceptibility patterns and risk factors associated with antimicrobial resistance.

Animals: Three hundred sixty-three positive urine cultures from 308 cats.

Methods: Bacterial species and antimicrobial susceptibility data from positive aerobic bacterial urine cultures from cats with growth of ≥10³ colony forming units per milliliter (cfu/ml) were included. Medical records were reviewed, and bacteriuria was classified as sporadic bacterial cystitis, recurrent bacterial cystitis or subclinical bacteriuria (SBU). Multivariable logistic regression analysis was used to evaluate antimicrobial resistance risk factors.

Results: A total of 444 bacterial isolates from 363 bacteriuric episodes were identified. Escherichia coli (52%) and SBU (59%) were the most common organism and classification, respectively. When compared to other classifications of bacteriuria, Enterococcus spp. were more likely to be isolated from SBU episodes (P < .001), whereas E. coli was more likely to be isolated from sporadic bacterial cystitis episodes (P < .001). Recurrent bacterial cystitis was associated with an increased risk of antimicrobial resistance to amoxicillin/clavulanic acid (odds ratio [OR], 3.9; 95% confidence interval [CI], 1.3-11.3). The percent susceptibilities of all bacterial isolates to commonly prescribed antimicrobials were amoxicillin/clavulanic acid (72%), cefazolin (49%), enrofloxacin (61%), and trimethoprim/sulfamethoxazole (75%). Multidrug resistance was highest for Enterococcus faecium isolates (65%).

Conclusions and clinical importance: No antimicrobial achieved >90% susceptible designation to all bacteria isolated highlighting the importance of performing urine culture and susceptibility testing, particularly for cats with recurrent bacterial cystitis.

Keywords: kidney; multidrug resistance; pyelonephritis; renal; subclinical bacteriuria; urinary tract; urinary tract infections.

FIGURE 1

Percent isolates of Escherichia coli and Enterococcus spp. of total bacteria per calendar year obtained from 363 bacteriuric episodes in cats over an 8‐year period.