Study of gyrA S83R Mutation Rate in Vancomycin Resistant Entrococcus Faecium

Enterococci are among Gram-positive cocci and are common inhabitants of the human gastrointestinal tract and enough potent to cause serious infections such as bacteremia, urinary tract infections (UTIs) and endocarditis. Enterococci are not generally considered as highly infectious bacterium. However, the main reason for treatment failure in enterococcal infections is acquired resistance to glycopeptide antibiotics, specifically vancomycin. Most enterococcal infections in human such as gastroenteritis, intestinal infections, and endocarditis have been caused by E. faecalis and E. facieum. They are holding the second place of most frequent cause of hospital infections since 1990. In present study gyrA S83R polymorphism rate in vancomycin resistant Enterococcus faecium isolated from environment, food industries, and hospitals of Tehran were examined by ARMS-PCR technique. DNA was extracted from the bacterial colonies using standard column method, after separating the samples into two groups of antibiotic resistant and antibiotic susceptible by antibiogram test. A fragment of gyrA gene was amplified using PCR method to investigate point mutation of S83R position. ARMS-PCR technique was applied to detect the presence or absence of mutation using a set of specified primers which can be annealed when the mutation is present. The results were statistically analyzed by chi-square test (p < 0.05) using SPSS 19th version. The results showed that there was a significant correlation between the presences of S83R polymorphism with vancomycin resistance trait in Entrococcus faecium. Therefore, this technique could be used as a diagnostic tool to detect vancomycin resistance cases of E. faecium in patients and environment. HIGHLIGHTS •There is a strong association between the presence of point mutation at the position of Ser83 and vancomycin resistant phenotype. •Resistance in Enterococcus spp. is highly mediated by mutations in gyrA gene which plays a major role in interaction with vancomycin. •Vancomycin is the only drug that can be consistently relied on for the treatment of infections caused by multidrug resistant enterococci. •VRE has presented a serious challenge for the Iranian medical community.