1468. Determination of Antibiotic Susceptibilities in Aerococcus urinae Urinary Isolates

Abstract

Background Aerococcus urinae is a Gram-positive organism, initially identified in 1992. It is known to cause urinary tract infections (UTIs), bacteremia, and endocarditis in humans. There is limited data regarding the susceptibility of A. urinae to first-line antimicrobials indicated for the treatment of UTIs. In 2016, A. urinae was isolated in 125 urine samples processed by the Integrated Hospital Laboratories Service, which services four hospitals in Southwestern Ontario, Canada. The unfamiliarity with this organism and the lack of local antimicrobial susceptibility rates presents a challenge for clinicians and often results in the unnecessary use of broad-spectrum antibiotics. The primary objective of this study was to establish the susceptibility rate of A. urinae urinary isolates to cefazolin, ampicillin, nitrofurantoin, fosfomycin, and ciprofloxacin. The secondary objective was to identify demographic characteristics associated with A. urinae bacteriuria in our patient population.MethodsUrinary samples received by the laboratory from October 2017 to June 2018 underwent routine identification as per physician orders. Samples that grew A. urinae were included in this study and subjected to susceptibility testing. Susceptibility testing was conducted via disk diffusion and results were interpreted based on published breakpoints for zone diameters.ResultsA total of 72 isolates were included. Susceptibility rates for cefazolin, ampicillin, nitrofurantoin, fosfomycin, and ciprofloxacin were 100%, 99%, 99%, 96%, and 65%, respectively. The average age of patients was 79 years, 63.9% were female, 31.9% were recently hospitalized, and 44.4% were residents of a long-term care facility.ConclusionCefazolin, ampicillin, nitrofurantoin, and fosfomycin demonstrated good in vitro activity against A. urinae. In contrast, ciprofloxacin demonstrated decreased activity against this organism. Currently recommended first-line agents for the management of uncomplicated UTIs could be utilized to treat this organism. Characteristics of patients with A. urinae bacteriuria are consistent with risk factors predisposing to UTIs. Disclosures All authors: No reported disclosures.

Macrolide Resistance in the Aerococcus urinae Complex: Implications for Integrative and Conjugative Elements

“…Similar to other emerging uropathogens, the AUC is poorly characterized and remains a blind spot in both disease and antibiotic resistance surveillance [17]. Worryingly, studies have been reporting antibiotic resistance, such as to fluoroquinolones, macrolides, and trimethoprim-sulfamethoxazole [18][19][20][21]. The current recommended empiric antimicrobial treatment for A. urinae urinary tract infection is the use of ampicillin, tetracycline, and nitrofurantoin [22].…”