Pathogenic Escherichia coli causes infections responsible for economic losses in animal herds worldwide. Although this bacterium is well studied in livestock and poultry, studies of camelid infections caused by extraintestinal pathogenic E. coli (ExPEC) are limited.
A set of extraintestinal E. coli from camel carcasses (n = 150) collected between 2004–2019 in the United Arab Emirates was characterized with respect to phylogenetic groups, 162 O serotypes, 36 bacteriocins, and 35 virulence-associated genes (VAGs) using PCR screening. To identify potential reservoir of camel ExPEC strains, fecal E. coli (n = 139) from healthy adult camels were also analyzed.
Our findings revealed that phylogroups B2 and C, and serotypes O6, O78, O86, and O118/O151 were significantly associated with ExPEC isolates. ExPEC isolates, on average, carried significantly more VAGs compared to fecal isolates (5.8 vs. 1.6 per isolate, p < 0.001); particularly those related to adhesion (afaI, fimA, pap, sfa, tsh), iron acquisition (fyuA, iroN, iucC, sitA), damage to the host cell (α-hly, cdt, cnf1, sat), invasion (ibeA), and bacterial protection (iss, ompT, traT). Moreover, ExPEC isolates showed a higher prevalence of 19 VAGs compared to fecal E. coli (p < 0.001). Additionally, ExPEC isolates frequently harbored bacteriocin genes, notably those encoding colicins B, Ia, M, and microcins L, V, PDI. These characteristics clearly differentiated between ExPEC and fecal isolates, which suggests an exogenous source of camel ExPEC infections, likely wild birds and/or human keepers.
Our findings provide insight into potential sources of camel ExPEC infections, which could help with the prevention and control of this important infection in camel herds.
The work was funded by the National Institute of Virology and Bacteriology (Programme EXCELES, ID Project No. LX22NPO5103, Funded by the European Union - Next Generation EU).