Antimicrobial resistance in ovine production: maternal-descendant similarities in Coliforms and Enterococcus spp.

Abstract

Abstract: Reports are scarce on the increase of antimicrobial resistance and the transfer of resistance from progenitor to progeny in production animals. Given this scenario, it is essential to understand how bacterial resistance mechanisms spread in ovine culture. The aim of this study is to identify the occurrence of antimicrobial resistance in Coliforms and Presumptive (P.) Enterococcus spp. present in progenitors and their descendants during the birth and weaning periods. Twenty-six pregnant ewes (Ovis aries) with an average body weight of 40 ± 2.0 kg and a body condition score of 3.5 ± 0.3 were used. Blood and fecal samples were collected from both dams and offspring for complete blood count analysis and antimicrobial susceptibility testing (AST). The AST was performed against the antibiotics penicillin, tetracycline, enrofloxacin, ampicillin, streptomycin, erythromycin and ceftiofur, targeting the bacterial genera Coliforms and Enterococcus spp. The results have shown that in the birth and weaning period, the progenitor and progeny had similarity to the susceptibility tests. Antibiotics such as erythromycin and penicillin presented high resistance levels. Furthermore, ceftiofur, an antibiotic not used in sheep farming, showed isolated cases of resistance. Although these occurrences were low and not widespread, the findings highlight the potential impact of pre-existing bacterial resistance mechanisms on the effectiveness of newer antimicrobials. It is concluded that there is a maternal-descendant similarity between both bacteria. The antibiotics ceftiofur, tetracycline, streptomycin, ampicillin and enrofloxacin showed lower resistance; erythromycin and penicillin showed higher resistance. Specific studies are recommended for each ovine production to control the resistance offered by erythromycin and penicillin. Key-words: Antibiotic; ewe; lamb; sensitivity; susceptibility.