Investigation of Glycopeptide Susceptibility of Coagulase-Negative Staphylococci (CoNS) From a Tertiary Care Hospital in Gorgan, Northern Iran

Abstract

Background: Coagulase-negative staphylococci (CoNS) are clinically important, especially in nosocomial and neonatal infections. The increasing emergence of glycopeptide-resistant CoNS has made these agents therapeutically challenging. Objectives: We aimed to investigate the susceptibility patterns of CoNS to teicoplanin and vancomycin in Gorgan, northern Iran. Materials and Methods: A total of 100 clinical samples were obtained from different wards of a hospital and screened for CoNS with standard microbiological and biochemical tests. Antibiogram testing was carried out for the detection of vancomycin-, teicoplanin-, and multidrug-resistant (MDR) species. The minimum inhibitory concentration (MIC) of vancomycin was determined using E-test strips. The presence of the vanA gene was investigated with PCR. Results: Only 1% of CoNS (Staphylococcus haominis) showed resistance to vancomycin and 15% of these were intermediate-resistant to teicoplanin on the disc diffusion agar test. In addition, all isolates (100%) were negative for vanA on PCR and sensitive with E-test methods. The mean MIC value of vancomycin was 1.35 ± 0.29 µg/mL. S. haemolyticus and S. epidermidis showed the highest rates of MDR (50% and 24%, respectively). Additionally, CoNS isolated from blood (42%) and urine samples (30%) had the highest rates of MDR. Conclusions: Vancomycin, but not teicoplanin, can be considered an effective antibiotic of choice for controlling infections caused by MDR CoNS in Gorgan, depending on the bacterial species.