Tetracycline-Resistant, Third-Generation Cephalosporin–Resistant, and Extended-Spectrum β-Lactamase–Producing Escherichia coli in a Beef Cow-Calf Production System

Abstract

Cow-calf production plays a significant role in the beef production chain. However, it is not typically monitored for antimicrobial resistance (AMR). We determined the baseline level of bacterial AMR in pre-weaned calves prior to feedlot entry and evaluated wheat grazing and age effects on their occurrence. Two grazing experiments, with 16 cow-calf pairs each, were conducted on tall fescue or wheat. Fecal samples were cultured for the detection of tetracycline (TETr )-, 3rd generation cephalosporin (3GCr )-resistant, and extended spectrum β-lactamase (ESBL) producing E. coli. Isolates were characterized for resistance to other antibiotics and resistance mechanisms. Concentration (P <0.001) and prevalence (P =0.007) of TETr E. coli were significantly higher in the claves (5.1 log10 CFU/g and 93%, respectively) than in the cows (4.4 log10 CFU/g and 80%, respectively). Wheat grazing did not affect TETr E. coli phenotypically however, it significantly (P =0.005) expanded the resistant population carrying tet(A) over tet(B). Fecal prevalence of 3GCr- and ESBL producing-E.coli was 31.3% and 3.4%, respectively with no significant effects of age (P =0.340) or wheat grazing (P =0.597). All 3GCr – and ESBLs producing- E. coli isolates were multidrug resistant. 3GCr were positive for blaCMY-2 (73%) or blaCTX-M (27%) and blaCTX-M-15 was the most prevalent (94%, n=17) among the CTX-M positive isolates. Wheat grazing significantly (P <0.001) expanded 3GCr population carrying blaCTX-M while reducing the blaCMY-2 carrying population. Five of the seven ESBL producing E. coli isolates were positive for blaCTX-M. Our study found age-dependent occurrence of TETr E. coli, and that wheat grazing expanded the resistant population carrying certain resistance mechanisms over others. Cow-calf production is a significant reservoir for antibiotic resistant bacteria of significant public health importance such as 3GCr- and CTX-M type ESBLs producing-E. coli.

The characterisation of antimicrobial resistantEscherichia colifrom dairy calves

“…Globally the prevalence of ESBL positive samples from calves range from 13-30% in the USA to 30% in Europe (Agga et al, 2022;Haenni et al, 2014b;Salaheen et al, 2019). In our study those ACBL producing E. coli isolated were putative chromosomal mediated, with the mutations found in the promoter region of the ampC gene previously described in E. coli isolates from both calves and adult cattle (Alzayn et al, 2020;Hordijk et al, 2013b;Santiago, 2019).…”

“…Previous studies have found that the prevalence of antimicrobial resistant E. coli and their genes is greater in calves compared with adult cattle (Agga et al, 2022;Geser et al, 2012;Khachatryan Artashes et al, 2004;Weber et al, 2021). Although our study did not directly compare calves with adult cattle, MDR E. coli have rarely been isolated from New Zealand adult cattle (Burgess et al, 2021a;Burgess et al, 2021b;Collis et al, 2019).…”

Effects of age and pasture type on the concentration and prevalence of tetracycline and macrolide resistant Enterococcus species in beef cow-calf production system

“…Much like the species distribution, wheat grazing affected the distribution of the tet and MLS B genes by either increasing [tet(O), erm(B)] or decreasing [tet(L), msr(C)] their prevalence. Wheat grazing had a similar effect on resistance gene distribution among TET r and third generation cephalosporin resistant E. coli isolates characterized from the same cow-calf populations (Agga et al, 2022b). These findings suggest that wheat grazing significantly affects the resistance gene distribution by favoring the expansion of bacterial population carrying certain genes, while suppressing bacterial population carrying other genes despite conferring the same phenotypic resistance.…”

“…The mechanisms and benefits to calves grazing on wheat need to be explored for the mitigation of AMR, especially because calves go to feedlot for beef production, with food safety implication. However, we previously reported from the same cow-calf population that wheat grazing had no effect on the prevalence and concentration of TET r E. coli (Agga et al, 2022b) suggesting the differential effect of wheat grazing on Grampositive and Gram-negative bacteria.…”

The characterisation of antimicrobial resistant Escherichia coli from dairy calves

“…coli could be due to New Zealand dairy farms being low users of antibiotics, particularly third and fourth generation cephalosporins [61, 62, 75]. Globally the prevalence of ESBL positive samples from calves range from 13–30 % in the USA to 30 % in Europe [71, 73, 76]. In our study those ACBL producing E.…”