Molecular identification of Enterococcus spp associated with subclinical mastitis in dairy animals in Algeria and their antimicrobial resistance profile

Abstract

Enterococcus genus is one of the opportunistic pathogens and responsible for mastitis in dairy animals. This study aimed to investigate the occurrence of enterococci associated with subclinical mastitis in goat, cow and camels in Algeria and to assess their antimicrobial resistance profiles. A total of 374 milk samples from udder quarters were tested for a subclinical mastitis (SCM) using the CMT. The positive samples were subjected to microbiological analysis for identification of Enterococcus spp by biochemical and molecular techniques using 16S rDNA sequencing and phylogenetic analyses. Eight strains of enterococci were tested to their antibiotic sensitivity profiles. The data revealed that 34, 31% of samples showed presence of SCM, meanwhile Enterococcus spp were occurred in 38.9% of positive milk. According to phenotypic criteria, 50 isolates were identified as Enterococcus faecium 70% (35/50) followed by Enterococcus faecalis 18% (9/50) and 12 % (6/50) were nonenterococci. Only eight isolates were confirmed to be Enterococcus spp using 16S rDNA sequencing technique. The antibiotic susceptibility showed that 85.5 % and 62.5% of Enterococcus feacium were resistant to Oxacillin and Penicillin respectively, while most of isolates were susceptible to Ciprofloxacin. In this study, Vancomycin-resistant enterococci (VRE) were found in 37.5% of isolates. Nevertheless, 62.5% of the tested strains displayed multi-drug resistances (MDR) across different patterns. This study highlights virulence and harmfulness of Enterococcus strains isolated from subclinical mastitic milk, which suggest continuous inspection and monitoring of dairy animals in Algeria.