Phenotypic and Genotypic Characterization of Aminoglycoside Resistance Profiles and SCCmec Types in Coagulase Negative Staphylococcus Isolates in Shahroud Hospitals

CoNS, as opportunists, are responsible for severe nosocomial and health-care related infections. This study aimed to investigate the prevalence and distribution of aminoglycoside resistance genes encoding aminoglycoside-modifying enzymes (AMEs) and to simultaneously address the SCCmec types in CoNS isolated from patients and healthcare workers.

A total of 130 isolates including 80 clinical isolates and 50 healthcare worker isolates (HCWs), were collected from two hospitals examined for their susceptibility to gentamicin, tobramycin and amikacin using disc diffusion. AME genes and SCCmec types were detected by the Multiplex PCR assay.

The resistance rate to gentamicin, tobramycin and amikacin was 67.5%, 56.3%, and 40% respectively. In addition, resistance to gentamicin was predominant among both patients and healthcare workers isolates. Also, aac(6`)-aph(2”)-Ia gene was the most prevalent, occurring in 56.3% of isolates, followed by ant(4`)-Ia gene at 18.8%. In contrast, 23.8% isolates lacked any AMEs genes. SCCmec types I, II, III, IV, and V were identified in 62.5%, 1.6%, 29.7%, 1.6%, and 6.3% of isolates, respectively. The combinations of types I + III and III + V were found in 18.8% and 4.7% of isolates, respectively, while 21.9% of isolates were non-typeable.

In this study, the emergence of aminoglycoside resistant strains was observed among clinical and health care workers isolates. Furthermore, SCCmecI was the most abundant type detected, demonstrating that there are different types among the isolates in different regions.