Skin And Soft Tissue Infections Associated with Methicillin Resistant Staphylococcus Aureus, Esbl, Amp C And Metallo Β- Lactamase Producing Bacilli In A Tertiary Care Hospital

Introduction: Skin and soft tissue infections (SSTI’s) are commonly caused by both gram positive and gram negative bacteria. The aim of the study was to investigate the presence of methicillin resistant Staphylococcus aureus (MRSA), Extended Spectrum Beta Lactamase (ESBL), Amp C and Metallo β-lactamase producing gram negative bacilli from clinical isolates obtained from patients attending G.S Medical College and Hospital, Pilkhuwa, Uttar Pradesh, India. Materials and Methods: A total of 263 clinical isolates obtained from skin and soft tissue infections were processed from September 2016 to May 2017 in this study. The isolates were identified by conventional microbiological methods and Antimicrobial susceptibility testing was done on Mueller Hinton Agar plate by Kirby Bauer’s disc diffusion method. All the organisms suspected to be methicillin resistant Staphylococcus aureus (MRSA) among gram positive cocci and those gram negative bacilli producing ESBL were detected by phenotypic confirmatory disc diffusion test (PCDDT) as per Clinical and Laboratory Standard Institute (CLSI) criteria. Amp C detection in gram negative bacilli was done by using Amp C Disc test while Metallo βlactamase production was detected by ImipenemEthylene Diamine Tetra Acetic acid (EDTA) combined disc test. Result: Out of the 263 clinical isolate tested, 162(61.6%) were gram positive cocci and 101 (38.4%) gram negative bacilli. MRSA accounted for 16 % of total isolates. Among gram negative bacilli, 22.8% were found to be pure ESBL producers by the PCDDT method and 23.8 % pure Amp C producers by Amp C Disc test.Metallo β-lactamases (MBL)accounted for 16.8 % of gram negative isolates. Co-expression of ESBL and AmpC was observed in 4.9% while in 8.9% isolates AmpC production was associated with MBL production. ESBL production was predominantly noticed in Escherichia coli and Proteus mirabilis while Amp C production was most common in Klebsiella spp followed by Pseudomonas aeruginosa. One third of Acinetobacter isolates were found to be pure metallo β-lactamase producers. Conclusion: Since MRSA, ESBL’s, Amp C and MBL producing gram negative bacilli are on a constant rise, it is very necessary to detect all the organisms isolated from cases of SSTI’s for these mechanism of resistance. Regular detection of these bacteria in clinical microbiology laboratory helps in guiding the physicians regarding empirical use of antibiotics and also in incorporating strategies for control measures to prevent spread of drug resistant organisms.