Urinary Tract Infection Due to Coagulase-negative Staphylococci: Species Identification, Antimicrobial Resistance and Clinical Characteristics

Moon, Hee Won; Lee, Mi Ae

Abstract

BACKGROUND: Previously considered as nonpathogenic contaminants, coagulase-negative staphylococci (CoNS) are now a major cause of nosocomial infections as increased use of prosthetic devices, intravascular catheters, and other invasive technology in more immunosuppressed patients and urinary tract infections (UTI) due to CoNS have been reported. In present study, species frequency, antimicrobial susceptability and clinical characteristics of CoNS UTI were evaluated. METHOD: We performed species identification and antimicrobial susceptibility of 109 CoNS strains isolated from urine in Ewha Womans University hospital from January 1998 to December 2002 and analysed clinical characteristics of 57 cases with CoNS UTI cases, retrospectively.
RESULTS
Among 13,336 strains isolated from urine, 109 strains were CoNS showing 0.8%. The most common species of CoNS from urine were S. epidermidis (49.5%) followed by S. haemolyticus (16.5%), S. saprophyticus (13.8%), S. auricularis (1.8%), S. simulans (0.9%) and unidentified CoNS represented 17.4%. The antimicrobial susceptibility showed high resistance to multiple drugs. Among CoNS, S. haemolyticus showed the highest resistance whereas S. saprophyticus showed the highest susceptibility to multiple drugs. The patients isolated S. saprophyticus were younger (mean age: 41 yrs) than those isolated other CoNS (mean age: 53 yrs) and more frequently female (9/14 vs 19/43). The hospitalized patients (74.4% vs 21.4%), bacteriuria more than 10 5 CFU/ml (83.7% vs 64.3%), indwelling catheter (34.9% vs 7.1%) and other risk factors (48.8% vs 35.7%) were more common in patients isolated other CoNS than those isolated S. saprophyticus and no significant differences were noted in pyuria (51.2% vs 57.1%). The symptomatic presentations were more common in patients isolated S. saprophyticus than those isolated other CoNS (71.4% vs 9.3%) and so were treatment (85.7% vs 44.2%).
CONCLUSIONS
When CoNS other than S. saprophyticus isolated from urine in hospitalized patientes with risk factors, identification and antimicrobial susceptability test is necessary for proper management.