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Abstract
Objective: This study was aimed to investigate the sensitivity of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from various clinical specimens against fusidic acid and other non β-lactam antibiotics including linezolid, quinupristin/dalfopristin, chloramphenicol, rifampin, levofloxacin and ciprofloxacin.
Methods: 84 MRSA strains isolated from various clinical specimens between January 2011 and December 2014 were included in the study. Strains isolated from laboratory specimens were identified as S. aureus by conventional methods (Gram stain, catalase and coagulase tests). The methicillin resistance of the strains was determined by disk diffusion method using cefoxitin (10 μg) disk. As there are no zone diameter breakpoints of vancomycin for Staphylococcus spp. by European Committee on Antimicrobial Susceptibility Testing (EUCAST), minimal inhibitor concentration (MIC) values were investigated with the Etest®. In vitro susceptibility of MRSA strains to other non β-lactam antibiotics was tested by Kirby-Bauer disk diffusion method using fusidic acid (10 μg), linezolid (10 μg), quinupristin/dalfopristin (15 μg), chloramphenicol (30 μg), rifampin (5 μg), ciprofloxacin (5 μg) and levofloxacin (5 μg) disks. The MIC values of vancomycin tested by Etest® and zone diameters of the antibiotics tested by Kirby-Bauer disk diffusion method were interpreted according to EUCAST criteria.
Results: The distribution of 84 MRSA strains by clinical specimens was 56% wound, 32.1% blood and 11.9% urine. The services that the strains were mostly isolated were Internal Medicine (17.9%), Anesthesia and Reanimation Intensive Care (16.6%), Neurosurgery (14.3%), Orthopedics and Traumatology (11.9%), and Paediatrics (11.9%). MICmin-max, MIC50 and MIC90 values of vancomycin were determined as 0.75 μg/mL-1.5 μg/mL, 1 μg/mL and 1.5 μg/mL, respectively. All strains were sensitive to vancomycin, linezolid and quinupristin/dalfopristin. Antimicrobial susceptibility rates were found to be 96.4% for chloramphenicol and 76.2% for fusidic acid, which were 20.2%, 19% and 16.6% for rifampin, levofloxacin and ciprofloxacin, respectively.
Conclusions: Although glycopeptides are the first choice in the treatment of MRSA infections, it should be taken into consideration that fusidic acid may be used as an alternative treatment, according to antimicrobial susuceptibility testing results in appropriate indications to prevent resistance development. Klimik Dergisi 2019; 32(1): 52-6.
Cite this article as: Coşkun MV, Alper Y, Uyanık MH, Yazgı H. [Sensitivity of methicillin-resistant Staphylococcus aureus strains to fusidic acid and other non-β-lactam antibiotics]. Klimik Derg. 2019; 32(1): 52-6. Turkish.