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Highlights • SHV-ESBL was detected in E. coli and K. peumoniae clinical isolates. • bla SHV-10 , bla SHV-18 , bla SHV-58 and bla SHV-91 were the most predominant variants. • New point mutations were detected in bla SHV and altered bla SHV enzyme binding sites. • bla SHV gene co-transfer was determined among isolates from human and poultry. • These data are valuable in the field of epidemiology and preventive medicine fields. Abstract The emergence of multidrug-resistant (MDR) pathogens was reported worldwide. Herein, SHV extended-spectrum β-lactamase (SHV-ESBL) variants detection was investigated in MDR E. coli and K. pneumoniae isolates recovered from human subjects (n = 144), one day-old chicks (n = 36) and broiler clinical samples (n = 90). All examined samples were positive for E. coli (n = 246/270; 91.11%) and Klebsiella pneumoniae (n = 24/270; 8.89%). Antimicrobial susceptibility testing was performed on E. coli and K. pneumoniae. SHV-ESBL producing isolates were defined followed by SHV-ESBL amino acids sequence and proteins structure-function analyses. Phylogenetic analysis of 11 MDR isolates resistant to at least 6 β-lactams was designed to determine their genetic relationship with those previously identified in Egypt. SHV-ESBL variants were detected in 28% and 16% of E. coli and K. pneumoniae isolates, respectively. Among the 11 SHV-ESBL producing isolates, one isolate displayed 100% bla SHV-12 similarity with three point mutations, while the other 10 isolates displayed amino acid substitutions at previously non-reported sites. Amino acid sequence analyses of these 10 isolates displayed 96–100% identity to bla SHV-10 (2 isolates with 3–6 point mutations), bla SHV-18 (one isolate with 4 point mutations), bla SHV-58 (4 isolates with 4–5 point mutations), and bla SHV-91 (3 isolates with 3–7 point mutations). These mutations altered SHV-enzyme pocket dimensions and its binding sites chargeability. The bla SHV phylogeny analysis revealed occurrence of variants in closely related lineages with bla SHV-5 and bla SHV-12 with possibility of bla SHV gene transfer between human and birds. The occurrence of these variants in Egypt could help in epidemiological studies and could explain the emergent resistance to β-lactams. [ABSTRACT FROM AUTHOR]