Identification and Characterization of Carbapenem-Resistant Organisms in Ventilator Associated Pneumonia from clinical isolates and direct clinical samples by Molecular Methods

Abstract

Background: Globally, ventilator-associated pneumonia (VAP) is most prevalent hospital acquired infection for patients admitted to an intensive care unit (ICU).The estimated attributable mortality of VAP is around 10%, with higher mortality rates in surgical ICU patients and in patients with mid-range severity scores at admission. Carbapenems are considered to be the most effective antibiotics against many multidrug resistant bacteria.Carbapenemases are encoded by the blaNDM, blaOXA, blaVIM, blaIMP, and blaKPC genes, which are located on both the plasmid and the chromosome. This investigation sought to ascertain whether the (Carbapenem resistant organisms) CRO isolated from VAP patients at a significant tertiary care facility in Navi Mumbai, Maharashtra, were carbapenemase producers. Objectives: This study aimed for identification and characterization of Carbapenem resistance gene in direct specimen and from clinical isolated organisms by molecular methods. Methods: This study was carried in one tertiary health care unit in Navi Mumbai Maharashtra, between Jan 2020 to Dec 2022. Phenotypic detectionwere performedusingantimicrobial susceptibility test (Kirby Bauer method and Modified Hodge test). Carbapenem producers likeblaNDM1, OXA48, OXA181, VIM, IPM, and KPCwere detected using a polymerase chain reaction (PCR) assay. Result:121 ET samples were examined, and 100 (82.64%) of them revealed significant bacterial growth. Acinetobacter species made up 37 (37%) Klebsellia species 21 (21%), Citrobacterspecies 17 (17%), Enterobacterspecies 5 (5%), and Proteusspecies 5 (5%), with the remaining 2 (2%) being other bacteria. The association between the molecular testing results for carbapenem resistance on direct patient samples and clinically isolated samples was examined. For each gene, the Phi value was computed. For early detection, NDM (Phi= 0.766), OXA 48 (Phi=0.854), OXA 181 (Phi=0.858), VIM (Phi=0.581), KPC (Phi=0.492) and IPM (Phi=0) demonstrates the significance and association because all phi values were more than 0.05. We advise using molecular techniques in clinical laboratories.