Methicillin-Resistant Staphylococcus Aureus, Extended Spectrum Betalactamase and Metallobetalactamase Production Among Organisms Causing Surgical Site Infections at a Tertiary Care Hospital in Bangalore

Abstract

BACKGROUNDInfection at or near surgical incisions within 30 days of an operative procedure, or within 1 year of an operation if a foreign body is implanted as part of the surgery is defined as a surgical site infection (SSI). They are the 2 nd most common cause of nosocomial infections. It has been estimated that SSI develops in at least 2% of hospitalised patients undergoing operative procedures. The incidence of Methicillin-Resistant Staphylococcus aureus (MRSA), extended spectrum betalactamase (ESBL) and metallobetalactamase (MBL) producing organisms have been steadily increasing over the past few years resulting in limitation of therapeutic options. MATERIALS AND METHODSIt is a descriptive study conducted from December 2014 to June 2016 at a tertiary care hospital, Bangalore. Samples were collected aseptically from the wound using sterile cotton swabs. Isolates were identified by conventional methods and their antibiogram pattern was studied by Kirby Bauer's disc diffusion method. Staphylococcus aureus when isolated was studied for MRSA using oxacillin and cefoxitin disc diffusion test. Gram-negative isolates resistant to cephalosporins and carbapenems during antibiotic susceptibility testing were studied for ESBL production using ceftazidime and cefotaxime disc diffusion test and MBL production using imipenem-EDTA combined disc test respectively using standard CLSI guidelines. All the statistical analysis was done by chisquare test using SPSS software. RESULTSOf 100 clinically diagnosed cases, 68 samples yielded growth of various bacterial isolates. 47 out of 56 cases (83.9%) from emergency surgeries and 21 out of 44 cases (47.7%) from elective surgeries were infected. Staphylococcus aureus was the most common organism isolated (32.9%) followed by Klebsiella pneumoniae (26.3%). MRSA was observed in 24% of Staphylococcus aureus isolates. ESBL production was observed in 23% of all Gram-negative isolates and MBL production was observed in 57% of all nil-fermenting Gram-negative isolates. CONCLUSIONSSIs are menacing problem for healthcare providers. The rise of MRSA, ESBL and MBL producing organisms and continuous change in the resistance pattern has made SSI a therapeutic challenge. Management of SSI involves lot of skill and treatment should be judiciously based on risk stratification. KEYWORDS SSI, MRSA, ESBL and MBL.HOW TO CITE THIS ARTICLE: Jain S, Gopi A, Samreen F, et al. Methicillin-resistant Staphylococcus aureus, extended spectrum betalactamase and metallobetalactamase production among organisms causing surgical site infections at a tertiary care hospital in Bangalore.