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

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.
We aimed to investigate the susceptibility patterns of CoNS to teicoplanin and vancomycin in Gorgan, northern Iran.
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.
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.
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.