The Characterisation and Antimicrobial Resistance of Coagulase Negative Staphylococci Cultured from Urinary tract Infections
Jodie Worsey
ABSTRACT
Coagulase negative Staphylococci are gram positive, catalase positive cocci, unable to coagulate and clot blood plasma. They are usually regarded as commensal flora and are abundant on skin surfaces. The recent emergence of these organisms as a cause of nosocomial infections has revealed their opportunistic nature, and they are now recognised as potential pathogens in the immunocompromised. S.saprophyticus has long been documented as a urinary tract pathogen in young women, although other species have not been thoroughly investigated. Recently, other coagulase negative Staphylococci have been cultured from the urine of patients whom are symptomatic for a urinary tract infection. This study aimed to explore these isolates to identify whether other species of this genus are associated with urinary tract infections in any other particular patient groups, and to determine the corresponding antimicrobial susceptibility patterns. Each isolate of coagulase negative Staphylococci cultured over a 4 month period was coagulase tested, identified by the Vitek2, and underwent antibiotic sensitivity testing via the BSAC disc diffusion method. The results revealed 3 isolates were misidentified by the hospital, 1 of which was a novobiocin sensitive strain of S.saprophyticus. The study also confirmed the known association of S.saprophyticus with sexually active young women, but additionally revealed a trend with post-menopausal women. Finally, it was found that S.epidermidis has an apparent connection to elderly males with underlining risk factors such as hospitalisation, post-operation, and morbidities including cancer and diabetes.
Keywords; Coagulase negative Staphylococci, urinary tract infection, commensal, biofilms, Vitek 2, disc diffusion, resistance, immunocompromised, elderly, nosocomial, opportunistic
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