Genomic and phenotypic profiling of Staphylococcus aureus isolates from bovine mastitis for antibiotic resistance and intestinal infectivity

Abstract

Background Staphylococcus aureus is one of the prevalent etiological agents of contagious bovine mastitis, causing a significant economic burden on the global dairy industry. Given the emergence of antibiotic resistance (ABR) and possible zoonotic spillovers, S aureus from mastitic cattle pose threat to both veterinary and public health. Therefore, assessment of their ABR status and pathogenic translation in human infection models is crucial. Results In this study, 43 S. aureus isolates associated with bovine mastitis obtained from four different Canadian provinces (Alberta, Ontario, Quebec, and Atlantic provinces) were tested for ABR and virulence through phenotypic and genotypic profiling. All 43 isolates exhibited crucial virulence characteristics such as hemolysis, and biofilm formation, and six isolates from ST151, ST352, and ST8 categories showed ABR. Genes associated with ABR (tetK, tetM, aac6’, norA, norB, lmrS, blaR, blaZ, etc.), toxin production (hla, hlab, lukD, etc.), adherence (fmbA, fnbB, clfA, clfB, icaABCD, etc.), and host immune invasion (spa, sbi, cap, adsA, etc.) were identified by analyzing whole-genome sequences. Although none of the isolates possessed human adaptation genes, both groups of ABR and antibiotic-susceptible isolates demonstrated intracellular invasion, colonization, infection, and death of human intestinal epithelial cells (Caco-2), and Caenorhabditis elegans. Notably, the susceptibilities of S. aureus towards antibiotics such as streptomycin, kanamycin, and ampicillin were altered when the bacteria were internalized in Caco-2 cells and C. elegans. Meanwhile, tetracycline, chloramphenicol, and ceftiofur were comparatively more effective with ≤ 2.5 log10 reductions of intracellular S. aureus. Conclusions This study demonstrated the potential of S. aureus isolated from mastitis cows to possess virulence characteristics enabling invasion of intestinal cells thus calling for developing therapeutics capable of targeting drug-resistant intracellular pathogens for effective disease management.

Hybrid Illumina-Nanopore assembly improves identification of multilocus sequence types and antimicrobial resistance genes of Staphylococcus aureus isolated from Vermont dairy farms: comparison to Illumina-only and R9.4.1 nanopore-only assemblies

“…It is also noteworthy that the WGS-based prediction of AMR based on ARG presence was largely consistent with phenotypic AST results, underscoring the potential of WGS in predicting AMR accurately. Whole genome sequencing has been used by several studies to assess the potential for predicting AMR genes from genomes of pathogens and validating concordances with the phenotypic results [ 19 55 56 ]. In our study, we used five AMR databases to predict AMR genes to prevent the chance of missing any AMR acquired genes or chromosomal point mutation in the genes.…”

Bovine Mastitis: Examining Factors Contributing to Treatment Failure and Prospects of Nano-enabled Antibacterial Combination Therapy

“…The biofilm-forming ability has also been reported to be associated with bacterial invasiveness. , Previous studies have reported that the polysaccharide capsules could mask surface adhesins and further confirmed a correlation between invasiveness and the absence of capsule polysaccharides. , Recently, our group reported the ability of a library of mastitis S . aureus isolates from Canadian dairy farms to get internalized in human intestinal Caco-2 epithelial cells and cause intestinal infection in the Caenorhabditis elegans model . Moreover, we showed that the antibiotics, including β-lactams, cephalosporins, aminoglycosides, etc., which were effective during direct exposure, failed to remediate the intracellular infection …”

“…102,103 Recently, our group reported the ability of a library of mastitis S. aureus isolates from Canadian dairy farms to get internalized in human intestinal Caco-2 epithelial cells and cause intestinal infection in the Caenorhabditis elegans model. 89 Moreover, we showed that the antibiotics, including β-lactams, cephalosporins, aminoglycosides, etc., which were effective during direct exposure, failed to remediate the intracellular infection. 89 2.3.c.…”

“…aureus , show intracellular survival and multiply within mammary epithelial cells of the lactating udder parenchyma (Figure ). − This ability of bacteria protects them from host immune responses and makes them inaccessible to antimicrobials. , Internalization of S . aureus in the bovine mammary gland is facilitated through ligand-mediated endocytosis. , The cellular uptake of bacterial cells starts with docking fibrinogen-binding proteins (FnBP) to their specific receptor molecules on the host cell surface.…”

“…89 Moreover, we showed that the antibiotics, including β-lactams, cephalosporins, aminoglycosides, etc., which were effective during direct exposure, failed to remediate the intracellular infection. 89 2.3.c. Metal Scavenging Ability of Mastitis Pathogens.…”