Longitudinal Analysis of Antimicrobial Resistance among Enterococcus Species Isolated from Australian Beef Cattle Faeces at Feedlot Entry and Exit

Yohannes E Messele; Mauida F Hasoon; Darren J Trott; Tania Veltman; Joe P McMeniman; Stephen P Kidd; Wai Y Low; Kiro R Petrovski

doi:10.3390/ani12192690

Longitudinal Analysis of Antimicrobial Resistance among Enterococcus Species Isolated from Australian Beef Cattle Faeces at Feedlot Entry and Exit

Animals (Basel). 2022 Oct 6;12(19):2690. doi: 10.3390/ani12192690.

Authors

Yohannes E Messele¹, Mauida F Hasoon², Darren J Trott², Tania Veltman², Joe P McMeniman³, Stephen P Kidd^{2

4}, Wai Y Low¹, Kiro R Petrovski^{1

2}

Affiliations

¹ The Davies Livestock Research Centre, School of Animal and Veterinary Sciences, University of Adelaide, Adelaide, SA 5005, Australia.
² The Australian Centre for Antimicrobial Resistance Ecology, University of Adelaide, Adelaide, SA 5005, Australia.
³ Meat & Livestock Australia, Level 1, 40 Mount Street, North Sydney, NSW 2060, Australia.
⁴ Research Centre for Infectious Disease, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia.

Abstract

Enterococcus faecium are commensal bacteria inhabiting the gastrointestinal tract of animals and humans and an important cause of drug-resistant nosocomial infections. This longitudinal study aimed to determine whether changes in the antimicrobial resistance (AMR) phenotype and genotype occurred among Enterococcus spp. isolated from cattle rectal samples obtained at the entry to and exit from an Australian feedlot. The samples obtained at the feedlot induction yielded enterococci (104/150; 69.3%), speciated as E. hirae (90/104; 86.5%), E. faecium (9/104; 8.7%), E. mundtii (3/104; 2.9%), E. durans, and E. casseliflavus (1/104; 1.0% each). AMR was observed to lincomycin (63/104; 60.6%), daptomycin (26/104; 25.0%), nitrofurantoin (9/104; 8.7%), ciprofloxacin (7/104; 6.7%), tetracycline (5/104; 4.8%), tigecycline (4/104; 3.9%), and quinupristin/dalfopristin (3/104; 2.9%). From the rectal swab samples collected at the abattoir from the same animals (i.e., the feedlot exit), the enterococci recovery was significantly higher (144/150; 96.0%), with a marked shift in species distribution dominated by E. faecium (117/144; 81.3%). However, the prevalence of AMR to individual antimicrobials remained largely static between the entry and exit except for the increased resistance to nitrofurantoin (77/144; 53.5%) and quinupristin/dalfopristin (26/144; 18.1%). Overall, 13 AMR genes were observed among the 62 E. faecium isolates. These included aac(6')Ii, aac(6')-Iid, and ant(6)-Ia (aminoglycosides); eatAv, lnu(G), vat(E), msr(C), and erm(B) (macrolides, lincosamides, and streptogramins); efmA (fluoroquinolones); and tet(45), tet(L), tet(M), and tet(S) (tetracyclines). The results confirm the presence of fluoroquinolone- and streptogramin-resistant enterococci in cattle faeces at the feedlot entry in the absence of antimicrobial selection pressure. E. faecium, exhibiting increased nitrofurantoin resistance, became the dominant Enterococcus spp. during the feeding period.

Keywords: cattle; microbiology; multidrug resistance; surveillance.

Grants and funding

B.FLT.3003/Meat & Livestock Australia