Characterization of coagulase-negative staphylococci isolated from hospitalized patients in Tehran, Iran

Coagulase-negative staphylococci (CNS) are a main cause of nosocomial infection. The main purpose of this study was to determination of frequency of CNS isolates in in hospitalized patients and their susceptibility pattern to antimicrobial agents. During 11 month study, 65 CNS clinical isolates were recovered from hospitalized patients in different wards of hospital. In vitro susceptibility of isolates to 12 antimicrobial agents Penicillin; Ampicilin; Cephalothin; Cefoxitin; linezolid; Nitofurantoin; Erythromycin; Norfloxacin; Gentamicin; Vancomycin; Chloramphenicol and Oxacillin was performed by Kirby-Bauer’s Disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) criteria. Out of 1875 samples of hospitalized patients 65(3.47%) patients were infected with CNS. Twenty one (32.3 %) were isolated from the urine samples, 17(26.1%) from sputum, 15(23.1%) from pus samples, 8(12.3 %) from ear swabs, 3(4.7%) from fluid and 1(1.5%) from blood sample. All of CNS isolates were sensitive to nitrofurantoin. The rates of resistance to the majority of antibiotics tested varied between 4.5% and 100 %. The rate of resistance to beta lactam antibiotics, Chloramphenicol, erythromycin, gentamycin was high (more than 70%). The most of isolates remained susceptible to linezolid, and nitofurantoin. All of isolates were susceptible to vancomycin. Multi-drug resistant CNS with reduced susceptibility to linezolid and nitrofurantoin are emerging pathogens of clinical concern. Monitoring of antibiotic resistance with attention to multi-resistant profile and aware to practitioners in the field is necessary.