Molecular Characterization of Antibiotic Resistant Gene of Staphylococcus SPP from Clinical Isolates in a Tertiary Care Hospital Puducherry South India

Abstract

Introduction: Staphylococcus aureus is considered as an important pathogen affecting skin and soft tissue1.It has the ability to reside and colonize asymptomatically in the normal human population. Being present as a reservoir on the body surfaces like anterior nares, skin and mucosa makes it a potent pathogen to cause infection under the favourable conditions. Current strategies in controlling the spread of MRSA infection should be rapid, accurate as well as simple. Molecular characterization of antibiotic resistant gene (mecA) by SCCmec typing is a widely accepted tool in identifying and classifying the MRSA isolates. SCCmec typing of MRSA could provide as an essential tool for medical experts and other epidemiologists in their effort to prevent and manage infections caused by these antibiotic resistant microorganisms. Simultaneously, detection of inducible clindamycin resistant and identification of carriers in MRSA, investigating the contributing factors and prompt treatment is essential in the management of MRSA infections. Aim and Objective: To characterize mecA gene responsible in methicillin resistance using SCCmec typing by Polymerase chain reaction. Materials and methods: Received specimen was observed for direct smear examination. All suspected organism grown from culture media were further studied by colony characteristics and various biochemical tests. The sensitivity for common antibiotics was done according to Kirby Bauer disc diffusion method followed from Clinical and Laboratory Standards Institute (CLSI) guidelines 2015. All the identified MRSA were screened by molecular technique (PCR) for locating mecA and molecular characterization of mecA gene was done by SCCmec typing as per the Boyde et al protocol. newlinevi newlineResults: The overall antibiotic susceptibility patterns were analyzed through chi-square test and it was found to show statistically significant for the antibiotics like Amikacin, Ciprofloxacin, Co-trimoxazole, Doxycycline, Erythromycin, Clindamycin, Vancomycin and Cefoxitin. All the MRSA strains were amplified by the PCR method and showed a visible clear band at a position of 310 base pair level. SCCmec typing reveals Type V as the most common type among the MRSA harboring the mecA gene which was followed by other SCCmec types. Conclusion: PCR is helpful in ruling out the indefinite reports and plays an important role in confirming the genetic element for the antibiotic resistance. Hence, with molecular characterization of the mecA gene our study highlights the prevalence of commonest type as SCCmec type V from our healthcare settings. This is the first study from Puducherry region which highlights the presence of SCCmec type V as the most prevalent one followed by the SCCmec type III and SCCmec type IV. Simultaneously, D-test is helpful in clearly delineating the inducible clindamycin resistance from the constitutive clindamycin resistance. Also, persons found to be nasal carriers should be rightfully advised for the timely treatment with the antibiotics. Repeat swabs should be collected to confirm the absence of colonization. newline newline