Evaluation of Co-production of Colistin Resistance and ESBL Genes among Gram-negative Clinical Isolates from Usmanu Danfodiyo University Teaching Hospital Sokoto, Nigeria

Abstract

Study’s Excerpt/Novelty • This study presents a comprehensive evaluation of colistin-resistant and extended-spectrum beta-lactamase (ESBL) gene co-production among Gram-negative clinical isolates from Usmanu Danfodiyo University Teaching Hospital in Sokoto. • Notably, 13.9% of the isolates exhibited phenotypic co-production of colistin resistance and ESBL, with a significant presence of blaCTX-M and CTX-M 8 genes among ESBL producers, although no colistin resistance genes (mcr-1 and mcr-2) were detected via PCR. • These findings highlight the necessity for integrated molecular and phenotypic investigations to fully elucidate resistance mechanisms in Gram-negative bacteria and emphasised the need for further research to uncover alternative pathways contributing to observed resistance phenotypes. Full Abstract The emergence of antimicrobial resistance (AMR) is a major threat to global health. Its effects include high mortality and morbidity rates, treatment failure, and increased treatment costs. This study aimed to evaluate the co-production of colistin-resistant and extended-spectrum beta-lactamase (ESBL) genes among Gram-negative clinical isolates from Usmanu Danfodiyo University Teaching Hospital in Sokoto. Gram-negative bacteria were isolated from clinical specimens, including urine, feces, and wound aspirates. The Double-Disk Synergy Test and the Colistin Agar Test, respectively, were used to phenotypically validate the existence of colistin resistance and ESBL. Polymerase chain reaction (PCR) was used for molecular characterization. Primers were used to target genes linked to colistin resistance (mcr-1 and mcr-2) and ESBL genes (blaCTX-M, CTX-M 1, CTX-M 2, and CTX-M 8). The findings indicated that 13.9% of the isolates displayed co-production of Colistin and ESBL, and of these isolates, 60% had blaCTX-M genes, and 20% had CTX-M 8 linked to ESBL production. However, the presence of colistin resistance genes was not detected by PCR. Therefore, molecular analysis did not confirm the existence of the colistin resistance genes (mcr-1 and mcr-2) in these isolates. Consequently, the findings showed no molecular co-production of the ESBL and colistin resistance genes. This work emphasizes how crucial it is to look into molecular and phenotypic traits to completely comprehend how colistin resistance and ESBL genes coexist in Gram-negative isolates. More research is required to investigate other mechanisms behind the resistance phenotypes identified.

Keywords

• colistin resistance
• esbl genes
• co-occurrence resistance
• gram-negative isolates