Antibiotic resistance in coagulase negative staphylococci isolated in the clinical laboratory of Balcali Hospital

Purpose: This study was carried out in order determine the antibiotic resistance in coagulase negative staphylococci isolated in the clinical laboratory of the Balcali Hospital. Methods: A total of 1114 coagulase negative staphylococci (CNS) investigated in this study. Results: Out of the 398 (35.73%) were found to be intrinsically resistant to oxacillin. The majority of the CNS produced beta lactamase (94.52%) and thus were resistant to penicillin and ampicillin. The intrinsic oxacillin resistant CNS were also resistant to amoxicillin/clavulanate, ampicillin/sulbactam, cefazolin, ceftriaxone and cephalothin. Staphylococci isolated from hospitalized patients showed a much higher rate of intrinsic oxacillin resistance in comparison to those from outpatients, 39.70% and 16.76%, respectively. Methods: The Sceptor system used in this study for identification of the CNS uses a panel which includes biochemical and antibiotic tests. This system usually did not classify the staphylococci to the species level. The majority of the CNS were identified as the S. epidermidis species group (81.15%). The sensitivity of the intrinsic oxacillin resistant CNS to other antibiotics such as clindamycin, erythromycin, gentamicin, rifampin and trimethoprim/sulfamethoxazole was very low (3.23- 17.59%). Conclusion: With the exception of vancomycin, ciprofloxacin was the most effective antibiotic