© 2011. Al Ameen Charitable Fund Trust, Bangalore 152 AJMS Al Ameen J Med Sci (2011)4(2):152-168 (A US National Library of Medicine enlisted journal) I S S N 0 9 7 4 - 1 1 4 3 ORIGINAL ARTICLE Isolation and Identification of Vancomycin Resistant Staphylococcus aureus from Post Operative Pus Sample Subhankari Prasad Chakraborty 1 , Santanu KarMahapatra 1 , Manjusri Bal 2 and Somenath Roy 1* 1 Immunology and Microbiology Laboratory, Department of Human Physiology with Community Health, Vidyasagar University, Midnapore -721 102, West Bengal, India and 2 Department of Human Physiology, Calcutta University, Kolkata, India. Abstract: Staphylococcus aureus is most frequently isolated pathogen causing bloodstream infections, skin and soft tissue infections and pneumonia. Recently, S. aureus have evolved resistance to both synthetic and traditional antibiotics. This study was carried out to isolate pathogenic S. aureus from post-operative pus sample, and VRSA was identified by evaluation of resistance patterns using conventional antibiotics. Thirty post operative pus samples were collected from nearby Hospital and species identification was confirmed by Gram staining, standard biochemical tests and PCR amplification of the nuc gene. Antibiotic susceptibility tests were carried out by MIC, MBC, DAD test and BHI vancomycin screening agar. VRSA were confirmed by PCR amplification of the vanA and vanB genes. From this study, it was observed that isolated S. aureus strains are pathogenic; 30% of strains were resistant to penicillin G, ampicillin and erythromycin; 26.67% strains were resistant to cephotaxime, gentamycin, streptomycin, tetracycline, chloramphenicol, norfloxacin, methicillin and vancomycin. Key-words: Staphylococcus aureus , vancomycin, antibiotic emergence, vanA and vanB gene, VRSA. Introduction Staphylococcus aureus , a Gram positive cocci, is major human pathogen causing large variety of infections worldwide and predominates in surgical wound infections with prevalence rate ranging from 4.6% - 54.4% [1-5]. S. aureus causes superficial skin infections to life-threatening diseases such as endocarditis, sepsis and soft tissue, urinary tract, respiratory tract, intestinal tract, bloodstream infections [6-7]. The species is identified on the basis of physiological or biochemical characters , by detection of eta and etb , staphylococcal enterotoxin genes and the Sa442 DNA fragment [9-11]. S. aureus has developed resistance to most classes of antimicrobial agents. Penicillin was the first choice of antibiotics to treat staphylococcal infection. In 1944, by destroying the penicillin by penicillinase , S. aureus become resistant . More than 90% S. aureus strains are resistant to penicillin . Methicillin, a semi synthetic penicillin was used to treat Penicillin Resistant Staphylococcus aureus but resistance finally emerge in 1962 [14-15]. MRSA is mediated by the presence of PBP-2a which is expressed by an exogenous gene, mecA . High prevalence of MRSA in hospitals has been reported from many states of India . MRSA isolates has reached phenomenal proportions in Indian hospitals, with some cities reporting 70% of the strains are resistant to methicillin .
Al Ameen J Med Sci; Volume 4, No.2, 2011
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