Antimicrobial resistance of methicillin-resistant coagulase negative staphylococcal species in two government hospitals in Kuantan, Malaysia

The emergence of nosocomial infections caused by CoNS has led clinicians and researchers to reconsider the role of CoNS and methicillin-resistant CoNS (MR-CoNS) as important agents of nosocomial infections. This study was conducted on clinical isolates of MR-CoNS obtained from inpatients in Hospital Tengku Ampuan Afzan (HTAA) and International Islamic University Malaysia Medical Center (IIUM-MC) to determine their antimicrobial resistance profile. The isolates were cultured from clinical samples of blood, tissues, and swabs. Forty isolates (33 blood, 4 tissues, and 3 swabs) of MR-CoNS were collected through venepuncture, biopsy, and swabbing techniques respectively, and processed by conventional cultural, biochemical methods and antimicrobial susceptibility tests. Methicillin- and vancomycin-resistance profile of the isolates was performed by E-test and broth micro-dilution methods. Of the 40 isolates, 38 were identified to be methicillin-resistant (MIC ³ 0.5 µg/mL). The remaining 2 isolates were considered as susceptible to methicillin (MIC ≤ 0.25). All 40 isolates were found to be susceptible to vancomycin (MIC=1-4 µg/mL). All 40 isolates were also tested for phenotypic antimicrobial susceptibility profile using the Kirby and Bauer disc diffusion method. Resistance rates to linezolid, erythromycin, ciprofloxacin, and ceftaroline were found to be 100%. Resistance rates to trimethoprim-sulfamethoxazole, teicoplanin, and clindamycin were found to be 82.5%, 92.5%, and 97.5% respectively. Thus, all the isolates revealed multi-drug resistance profiles to more than 3 antimicrobials; the highest being resistance to 9 antibiotics, except one isolate from swab. This points toward the need for periodic antibiogram surveillance as they are identified to cause difficult to treat infections.