Resistant Genes blaCTX-M, blaTEM and blaSHV encoding ESBL in surgical site infection causing Escherichia coli and Klebsiella pneumoniae- A report from a tertiary care hospital

Introduction: Surgical site Infections (SSI) rank third among hospital acquired infections worldwide. According to the WHO report of 2016, the global burden of SSI ranges from 2.5% to 41.5%. ESBL producing E.coli and Klebsiella pneumoniae are frequently being isolated from these infections owing to the high transmission density of plasmid-mediated ESBLs in hospital setting. Aim: To survey for antimicrobial resistance encoding genes of ESBL (blaTEM, blaCTX-M and blaSHV) among Escherichia coli and Klebsiella pneumoniae isolated from surgical site infections in a tertiary care hospital. Materials and Methods: A cross sectional study was carried out over a period of one year in the department of Microbiology, SRM Medical College from March 2016-March 2017. A total of 136 pus swabs or pus aspirates were collected from post-operative male and female adult patients. Microbiological investigations of Gram staining, Culture and biochemical tests were performed with the samples. Antimicrobial susceptibility testing for screening and phenotypic detection of ESBL production was carried out according to Clinical Laboratory and Standards Institute guidelines, 2016. Conventional Polymerase chain Reaction (PCR) was performed using specific primers to amplify ESBL encoding genes among ESBL producing Escherichia coli and Klebsiella pneumoniae isolates. Result: Out of 136 samples tested 76 (55.88%) Gram negative bacteria were isolated. The most common causative agent of SSI was Escherichia coli 30 (39.47%), followed by Klebsiella pneumonia 17 (22.37%). Phenotypic testing by combination disk method detected 40% of E.coli and 23.5% of Klebsiella to be ESBL producers. They were highly resistant to Ampicillin (86%) Cefepime (46.93%), Ceftazidime (62.75%) and Ciprofoloxacin (50.98%). blaTEM was the predominant ESBL gene detected by Conventional PCR. Conclusion: Early and accurate detection of ESBL is essential to reduce the spread of drug resistance among nosocomial bacteria.