Detection of Macrolid, Lincosamide and Streptogramin Resistance Genes in Methicillin-Resistant Staphylococcus Epidermidis Strains Isolated from Clinical Samples in Isfahan City, Iran

Increased antibiotic resistance among nosocomial infections has made the treatment of these infections difficult. Staphylococcus epidermidis is also known as one of the most common causes of nosocomial infections. The aim of this study was to determine the prevalence of resistance to macrolide, lincosamid and streptogramin antibiotics, in methicillin-resistant Staphylococcus epidermidis (MRSE) strains isolated from clinical samples and to detect their related resistance genes.
For a period of 8 months, from 250 clinical Staphylococcus strains, 100 isolates of Staphylococcus epidermidis were identified and the antibiotic susceptibility patterns of the isolates were determined using the disc diffusion method. MRSE samples were isolated by using the disk diffusion method for cefoxitin. The minimum inhibitory concentration (MIC) of erythromycin was determined using the micro dilution method. The frequency of inducible clindamycin resistance phenotype was detected via D test method and the resistance genes to MLSB were detected using polymerase chain reaction (PCR) method.
Findings: Among 100 Staphylococcus epidermidis strains, 52 isolates were MRSE. The frequency of resistance phenotype iMLSB, MS and cMLSB were 17.3%, 13.4% and 48%, respectively. The frequency of the resistance genes ermC, msrA and ermA were 73%, 11.5% and 5.7%, respectively.
The high frequency of the ermC gene among isolates is a serious warning to health systems; thus, use of convenient and effective treatment methods after antibiotic susceptibility tests is necessary.