Department of Microbiology

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Browsing Department of Microbiology by Author "ASH2305MS111M"

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    Integrative Genomic and Phenotypic Characterization of Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae (ESBL-E) and Related Bacterial Species Isolated from Pediatric Diarrheal Cases in Bangladesh.
    (2025-12-15) ASH2305MS111M
    Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) pose a major global threat to antimicrobial therapy, particularly in pediatric populations where diarrheal diseases remain a leading cause of morbidity and mortality. This study provides an integrative genomic–phenotypic assessment of ESBL-producing pathogens isolated from diarrheal stool samples of hospitalized children (<8 years) in Bangladesh. A total of 38 bacterial isolates obtained from 32 samples were identified to the species level using MALDI-TOF MS, with Escherichia coli (47.37%) and Klebsiella pneumoniae (10.53%) being predominant. Whole genome sequencing (WGS) revealed genome sizes ranging from 3.36–6.63 Mb and 3,095– 6,056 annotated coding sequences. Genomic screening using ABRicate across five AMR databases identified ESBL-associated genes in 55.3% (21/38) of isolates. The bla CTX-M-15 gene was the most prevalent variant (76.19%), primarily among E. coli, followed by blaTEM and blaSHV alleles. Phenotypic ESBL detection via CLSI-recommended double-disk synergy testing confirmed ESBL activity in 39.5% of isolates. Genotype–phenotype concordance was 78.95%, with genotype-positive/phenotype-negative mismatches likely linked to silent gene expression, masking by co-produced β-lactamases, or complex resistance mechanisms. Plasmid replicon analysis identified diverse incompatibility groups, including IncF, IncI, IncHI, IncX, IncR, and Col plasmids, supporting the mobility and dissemination of ESBL genes. Virulence profiling showed substantial heterogeneity, with ESBL-positive isolates carrying multiple adhesion, iron acquisition, and stress-response determinants that may enhance pathogenic potential. This study represents one of the first comprehensive genomic–phenotypic investigations of ESBL-producing Enterobacteriaceae in pediatric diarrheal cases in Bangladesh. The predominance of bla CTX-M-15, the complexity of plasmid-mediated gene dissemination, and notable genotype–phenotype discrepancies underscore the need for integrated WGS-based surveillance alongside refined phenotypic diagnostics. These findings offer critical insights for early detection, infection control, and therapeutic decision-making in resource-limited healthcare settings.