Phenotypic evaluation of antibiotic resistance and pathotyping of Escherichia coli isolated from healthy camels in Mashhad

This study aimed to investigate the antibiotic resistance and pathotyping of Escherichia coli isolated from healthy camels in farms around Mashhad, Iran. A total of 80 faecal swab samples were collected over a three-month period. Samples were cultured on MacConkey agar, and isolates were confirmed through biochemical tests. Pathotyping was conducted using virulence genes stx1, stx2, eaeA, STI, LTI, and ipaH. Results showed the following distribution among the 80 isolates: 14 isolates (17.5%) positive for the stx1 gene, 9 isolates (11.25%) positive for the stx2 gene, 15 isolates (18.75%) positive for the eae gene, 2 isolates (2.5%) positive for the LT gene, 6 isolates (7.5%) positive for the ST gene. None of the isolates (0%) tested positive for the ipaH gene. Antibiotic susceptibility testing revealed neomycin as the most effective antibiotic with 100% sensitivity. In contrast, complete resistance (100%) was observed to tetracycline and florfenicol. Streptomycin and chloramphenicol were highly effective, while gentamicin and erythromycin showed low sensitivity. Ceftazidime and ampicillin displayed moderate efficacy. The findings highlighted the pathogenic diversity of E. coli strains in camels and the alarming levels of antimicrobial resistance. The presence of multiple virulence genes suggests the involvement of a mix of pathotypes with potential implications for both animal and human health. The results also emphasise the need for targeted antimicrobial strategies based on specific resistance profiles.