Non-O157 Shiga toxin-producing Escherichia coli with potential harmful profiles to humans are isolated from the faeces of calves in Uruguay

Umpiérrez, Ana; Ernst, Déborah; Cardozo, Andrea; Torres, Alexia; Fernández, M. Fernández; Fraga, Martín; Vignoli, Rafael; Bado, Inés; Vidal, Roberto; Zunino, Pablo Enrique Abraham

doi:10.4067/s0719-81322022000200045

Cited by 5 publications

(6 citation statements)

References 41 publications

(64 reference statements)

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“…Other studies have indicated a possible higher presence of antibiotic resistance among non-O157 STEC serotypes from animal origin, including resistance against antimicrobials that are critical for human and veterinary medicine, carrying eae and stx1 genes, a combination of virulence and serotype detected in our work [ 43 , 44 ]. The high percentage of MDR-STEC isolates detected in our study differs from what was previously observed in STEC from feces of live calves [ 25 ]. In both studies, resistance to Ampicillin was the most prevalent among STEC, consistent with the fact that β-lactams are the most widely used antibiotics in animals [ 45 ].…”

Section: Discussioncontrasting

confidence: 99%

“…Among these, the occurrence of isolates with STEC virotype was very high (85%). In agreement with previous works [ 25 ], the 16 STEC isolates were identified with stx1 a and c subtypes, confirming their circulation in dead calves from Uruguay. These isolates were mainly assigned to groups B1 and E, followed by groups C and A, whereas the two hybrid STEC/NTEC isolates were assigned to the phylogroup A.…”

Section: Discussionsupporting

confidence: 92%

“…The NTEC isolates were also assigned to phylogroup B1 and the EPEC to phylogroup E. Our results only partially coincide with those of the literature, where STEC strains are often assigned to phylogroups B1 and E and EPEC to E [ 41 ]. In Uruguay, the heterogeneity in phylogenetic groups among STEC was previously noted in isolates recovered from bovine feces [ 25 ].…”

Section: Discussionmentioning

confidence: 99%

“…In both studies, resistance to Ampicillin was the most prevalent among STEC, consistent with the fact that β-lactams are the most widely used antibiotics in animals [ 45 ]. However, no non-O157 MDR-STEC strains were identified in living calves [ 25 ]. This difference could reflect the extensive use of antimicrobials in dairy herds to treat infectious diseases such as NCD, particularly in animals with a high risk of dying.…”

Section: Discussionmentioning

confidence: 99%

“…The presence of pathogenic E. coli isolates in the feces of calves has been reported in Uruguayan dairy herds, in both healthy and diseased animals with NCD, and its virulence profile, zoonotic potential, resistance phenotype and presence of transferable resistance genes have been described [ 23 , 24 , 25 , 26 ]. Taking into account the previous works carried out in this category of bovine, so far the proportion of STEC in feces is low, but with an important proportion of potentially harmful non-O157 STEC isolates [ 24 , 25 ]. However, the study of STEC associated with calves’ mortality remains unknown.…”

Section: Introductionmentioning

confidence: 99%

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Shiga Toxin-Producing Escherichia coli (STEC) Associated with Calf Mortality in Uruguay

et al. 2023

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In Uruguay, the mortality of dairy calves due to infectious diseases is high. Escherichia coli is a natural inhabitant of the intestinal microbiota, but can cause several infections. The aim of the work was to characterize E. coli isolates from intestinal and extraintestinal origin of dead newborn calves. Using PCR, virulence gene characteristics of pathogenic E. coli were searched. The pathogenic E. coli were molecularly characterized and the phylogroup, serogroup and the Stx subtype were determined. Antibiotic susceptibility was determined using the Kirby–Bauer disk diffusion method and plasmid-mediated quinolone resistance (PMQR) genes with PCR. Finally, clonal relationships were inferred using PFGE. Gene characteristics of the Shiga toxin-producing E. coli (STEC), Enteropathogenic E. coli (EPEC) and Necrotoxigenic E. coli (NTEC) were identified. The prevalence of the iucD, afa8E, f17, papC, stx1, eae and ehxA genes was high and no f5, f41, saa, sfaDE, cdtIV, lt, sta or stx2 were detected. The prevalence of STEC gene stx1 in the dead calves stood out and was higher compared with previous studies conducted in live calves, and STEC LEE+ (Enterohemorrhagic E. coli (EHEC)) isolates with stx1/eae/ehxA genotypes were more frequently identified in the intestinal than in the extraintestinal environment. E. coli isolates were assigned to phylogroups A, B1, D and E, and some belonged to the O111 serogroup. stx1a and stx1c subtypes were determined in STEC. A high prevalence of multi-resistance among STEC and qnrB genes was determined. The PFGE showed a high diversity of pathogenic strains with similar genetic profiles. It can be speculated that EHEC (stx1/eae/ehxA) could play an important role in mortality. The afa8E, f17G1 and papC genes could also have a role in calf mortality. Multidrug resistance defies disease treatment and increases the risk of death, while the potential transmissibility of genes to other species constitutes a threat to public health.

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