Dominance Of Chromosome-Borne CTX-M Extended Spectrum Beta-Lactamases (ESBL) in Gram-Negative Clinical Isolates
DOI: doi-org-10-51374-annalsmls-2024-3-1-0011
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Abstract
Background: Antibiotic resistance caused by Extended Spectrum beta-lactamase enzymes (ESBL) often lead to poor clinical outcomes in the treatment of bacterial infections of different aetiologies. The ESBLs have continued to emerge in different types with continued expansion in substrate specificity. In this study, conducted at the Federal Medical Centre, Owerri, Imo State Nigeria, from 2017 to 2019, we aimed to detect the presence of ESBL in multidrug resistant clinical isolates and to identify the types and location of the ESBL genes. Materials and Methods: In this comprehensive study, we isolated and characterized seventy-seven multidrug-resistant isolates, including 41 isolates of Escherichia coli, 26 isolates of Pseudomonas aeruginosa, and 10 isolates of Klebsiella pneumoniae, all from urine and wound swab specimens. Phenotypic ESBL detection was carried out using a double-disc synergy test (DDST). Plasmid DNA was extracted using the alkaline lysis method and the TENS method. The product was subjected to
gel electrophoresis on 0.8% agarose. Genomic DNA was extracted by the Norgens Genomic DNA extraction method. The extract was amplified on Multiplex Polymerase Chain Reaction (PCR) using a pair of each of three primers, namely: TEM
(Temoniera), SHV (Sulfhydryl variable), and CTX-M (Cefotaximase–Munich) genes. The amplified product was subjected to gel electrophoresis on 1.5% agarose. The bands were visualized in an ultraviolet transilluminator in a photo documentation
system.
Results: Up to 40.3% of the isolates were positive for ESBL phenotype. However, 66.7% of those positive for ESBL phenotype showed bands for ESBL genotype. One hundred percent of all ESBL positive genotypes possess CTX-M genes, while 31.3% showed co-expression of CTX-M and SHV genes. None of the isolates showed any band in the region of TEM gene. The predominance of Chromosomal borne CTX-M ESBL with 31.3% co-expression of SHV ESBL in multidrug-resistant isolates is hereby reported, with a total absence of both TEM ESBL and plasmids.
Conclusion: Massive infection control measures are needed to curb the rapid spread of drug-resistant genes. Prudent antibiotic stewardship and rational antibiotic policy are also needed to prevent the selection/induction of drug resistance under
antibiotic pressure.
Keywords: Extended Spectrum Beta-lactamase, CTX-M, SHV, TEM, Genes, Multidrug resistance.