Original article / research
Prevalence of Extended Spectrum Beta-lactamase Encoding Genes in Enterobacteriaceae Isolated from Various Clinical Samples in a Tertiary Care Cancer Centre, Kerala, India
Microbiology Division, Malabar Cancer Centre, Thalassery, Kannur-670103, Kannur, Kerala, India.
Introduction: Cancer patients are disproportionately at high risk of developing infections, with a risk of infection about 10 times than that of non cancer patients. Extended Spectrum Beta-Lactamases (ESBLs) enzyme producing gram-negative bacteria have been marked as one of the “serious” threat by the centre for disease control. This enzyme has the ability to hydrolyse the beta-lactam antibiotics and posses a major threat for the immunocompromised and cancer patients. Hence, understanding its prevalence at the grammatical level is important to decide upon the type of drugs to be prescribed.
Aim: To study the prevalence of ESBL genes among the GramNegative Bacteria (GNB) isolated from cancer patients.
Materials and Methods: The present study was a hospitalbased cross-sectional study carried out in Microbiology Division, Malabar Cancer Centre, Thalassery, Kerala, India, from January to March 2021. Microbiological identification of the causative agents was done by staining, culturing and biochemical methods. Screening of the isolates for ESBL was done using Double Disc Synergy Test (DDST). Antibiotic susceptibility testing was carried out using modified Kirby-Bauer disc diffusion method. The ESBL producers were genotypically confirmed through Polymerase Chain Reaction (PCR) and typed accordingly. The data were given as average with standard deviation and analysed using Microsoft Excel.
Results: Out of 1,310 specimens, 366 (27.9%) were culture positive. Among the GNB, Escherichia coli (50%) followed by Klebsiella pneumoniae (46.07%), Proteus (1.96%) and Enterobacter cloacae (0.98%) were the predominant isolates. Most of these ESBL producers (Escherichia coli, Klebsiella pneumoniae) were Multidrug Resistant (MDR). However, significant isolates of Escherichia coli (98.03%), Klebsiella pneumoniae (36.1%), Proteus, (50%) and Enterobacter cloacae (100%) were sensitive to immunocompromised. Among 102 ESBL producers, prevalence of blaTEM (67.64%) was highest followed by blaCTX-M (10.78%), blaSHV (14.70%) and blaOXA (18.62%). All of the ESBL producers tested showed the presence of one of four betalactamase encoding genes by PCR. One of the isolate Proteus mirabilis found to be ESBL producer as confirmed by phenotypic methods but lacked ESBL genes.
Conclusion: Higher prevalence of ESBL producing strains warrants stringent measures to tackle the spread of MDR strains. Carbapenems can be considered as the drug of choice against ESBL producers. Highly prevalent blaTEM gene could be considered as potential therapeutical and diagnostic target against the ESBL producing GNBs.
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