Research Article | 23 Feb 2026

Phenotypic and genotypic characterization of multidrug-resistant avian pathogenic Escherichia coli across life stages of captive African Houbara bustards: Conservation and One Health implications

Sara M. RashadShow more
VETERINARY WORLD | pg no. 654-666 | Vol. 19, Issue 2 | DOI: 10.14202/vetworld.2026.654-666
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Abstract

          
Background and Aim: The African Houbara bustard (Chlamydotis undulata), a species of high conservation concern, is maintained through intensive captive breeding programs where bacterial diseases may compromise productivity and reintroduction success. Escherichia coli is frequently implicated in reproductive failure, early mortality, and septicemic conditions; however, integrated phenotypic and genotypic characterization of antimicrobial resistance and virulence across life stages in this species remains scarce. This study aimed to determine the prevalence of E. coli across different life stages of captive African Houbara bustards, characterize multidrug-resistant (MDR), extensively drug-resistant (XDR), and extended-spectrum β-lactamase (ESBL) phenotypes, and profile avian pathogenic E. coli (APEC)–associated virulence genes within a One Health framework. 
Materials and Methods: A cross-sectional diagnostic investigation was conducted during the 2025 production season. A total of 110 samples were collected from early embryonic death (n = 50), chicks (n = 25), juveniles (n = 25), and adult females (n = 10). Isolation and identification of E. coli were performed using conventional bacteriology and the VITEK®2 system. Antimicrobial susceptibility testing was carried out using disk diffusion and VITEK®2 AST, with resistance patterns classified according to international MDR and XDR definitions. Phenotypic ESBL detection was undertaken, and a multiplex real-time polymerase chain reaction (PCR) assay targeting 15 APEC-associated virulence genes was applied to representative isolates. 
Results: E. coli was isolated from 62.7% (69/110) of samples, with the highest prevalence observed in juveniles (84%) and chicks (80%). All isolates were resistant to ampicillin and fluoroquinolones, while complete susceptibility was observed to fosfomycin, aminoglycosides, and chloramphenicol. MDR was detected in 96.9% of tested isolates, and one XDR isolate resistant to 15 antibiotics was identified. ESBL-producing E. coli were detected in juveniles (14%) and early embryonic death samples (9%). Virulence profiling revealed a high gene burden, with most isolates harboring ≥10 virulence genes, particularly those associated with iron acquisition, protectins, and invasion. 
Conclusion: Captive African Houbara bustards harbor highly virulent MDR and ESBL-producing E. coli across life stages, posing significant conservation, veterinary, and public health risks. Strengthened biosecurity, prudent antimicrobial stewardship, and integrated One Health surveillance are essential to improve breeding success and safeguard reintroduction programs. 
          
Keywords: African Houbara bustard, antimicrobial resistance, avian pathogenic Escherichia coli, captive breeding, extended-spectrum beta-lactamase, multidrug resistance, One Health, virulence genes.