Prevalence of ESBL producing Gram Negative Bacilli in Post Operative wound Infections

R. Lakshmi kumari¹, A. Geethanjali^2
1Professor & HOD, Department of Microbiology, Siddhartha Medical College, Dr. N.T.R.U.H.S, Vijayawada-520008, Andhra Pradesh, India.
²Post Graduate (M.D), Department Microbiology, Siddhartha Medical College, Dr. N.T.R.U.H.S, Vijayawada-520008, Andhra Pradesh, India

A B S T R A C T
To study the aerobic Gram Negative bacilli in Postoperative Wound Infections with special reference to Extended Spectrum β lactamases (ESBL). The study was conducted on 173 patients who underwent surgery in General Surgery department. Pus samples were collected with two sterile swabs and processed in Microbiology department by Standard methods. The overall surgical wound infection rate was 5.97%. of the 173 pus samples, 127(73.41%) showed growth, among these Gram Negative aerobic bacilli isolated was 79 (62.2%). Pseudomonas aeruginosa (31.6%) was the most predominant organism followed by Escherichia coli (22.7%) which, in turn followed by Klebsiella pneumoniae (18.9%). Out of the 79 isolates which were screened for ESBL production, 25(31.6%) isolates were found to be ESBL positive by CLSI disc diffusion and 23(29.1%) were positive by screening with HiCrome ESBL agar. On performing confirmatory tests on the 25 isolates which were ESBL positive by screening tests, 23 (92%)  were found to be ESBL producers on CLSI phenotypic confirmatory test and 22 (88%) were found to be ESBL producers on Double Disc Synergy Test. The prevalence of ESBL producing gram negative bacilli in postoperative wounds is 29.1% which were detected by screening and confirmatory tests.
Keywords: Surgical site infection (SSI), Extended spectrum beta lactamase (ESBL), Phenotypic confirmatory test (PCT), Clinical Laboratory Standards Institute (CLSI)