Presence of antibiotic-resistant Enterococcus faecalis in colostrum supplied to calves?

Colostrum can be responsible for colonizing calves gastrointestinal tract by antibiotic-resistant bacteria, such as Enterococcus faecalis one of the main indicators of fecal contamination and associated with nosocomial infections. In this work, the aim to characterize antibiotic resistance in E. faecalis isolates from colostrum used in the feeding of calves. Nineteen one isolates were recovered using agar selective plates and confirmed by biochemical and genetic tests. The antimicrobial susceptibility was performed using 14 antimicrobial agents by the disk diffusion method, according to the Clinical and Laboratory Standards Institute standards. The majority showed antibiotic-resistance to quinupristin-dalfopristin (81.3%), tetracycline (79.1%), erythromycin (79.1%) and streptomycin (57.1%). Isolates were less resistant to rifampicin (47.3%), chloramphenicol (25.3%) and ciprofloxacin (11.0%). Resistance to the remain antibiotics (vancomycin, teicoplanin, nitrofurantoin, fosfomycin and linezolid) was below 10%. None isolate showed resistance to ampicillin or gentamicin. In the 91 isolates analyzed, 85.7% proved to be multidrug-resistant. In conclusion, colostrum contains multidrug-resistant E. faecalis and constitutes a reservoir and vehicle for the transmission of these bacteria. For this reason, more prudent use of antibiotics in the therapy and prophylaxis of cattle is recommended, as well as, the correct management of the colostrum.