Phenotypic And Genotypic Characterization Of Carbapenem – Resistant Gram – Negative Bacteria Among Pediatrics With Positive Blood Cultures

Abstract

Background: Carbapenems are β-lactam antibiotics, which are regarded as one of the final options to treat severe infections resulting from multidrug-resistant organisms. Carbapenem resistance is mostly caused by carbapenemases, which are enzymes that break down this kind of β-lactam antibiotic. It can also occur through non-enzymatic processes such as efflux or changes in porin structure when AmpC or extended-spectrum β-lactamases (ESBL) are present. Carbapenemase-mediated resistance poses a far greater threat. Objectives: The aim of the study was to detect the underlying mechanisms of resistance of carbapenem resistant gram negative bacteria by phenotypic detection (lateral flow immunoassay) directly from positive blood cultures& genotypic detection (Conventional PCR). Methodology: This research was performed on clinical isolates of 25 positive blood cultures of carbapenem resistant Gram -ve bacteria from pediatric cases at Beni-Suef University Hospital. The isolates underwent identification & antimicrobial susceptibility testing by means of VITEK 2 compact system. We assessed a rapid lateral flow immunoassay (LFIA) directly on positive blood culture bottles for carbapenemase genes (OXA-48, KPC, NDM, VIM, and IMP) & compared outcomes with those obtained utilizing conventional polymerase chain reaction (PCR) techniques. Results: PCR test presented that OXA-48 was the most predominant genotype (96%), and the least prevalent was IMP (56%). We evaluated the results of the lateral flow immunoassay and found that the sensitivity of each type was in the range of 71.4%–100% and the specificity of each type was from 0%–90.9% in comparison with PCR as the gold standard. Conclusion: The lateral flow immunoassay is an effective & efficient phenotypic test for quickly identifying carbapenemase-generating isolates straight from blood culture bottles. It may also be utilized as a point-of-care test.