Staphylococcus (S.) aureus is a common infectious agent of bovine chronic mastitis, a disease that is difficult to eradicate. The abilities of Staphylococci to be internalized and form a biofilm can contribute to host immunological defence evasion that subsequently impairs antimicrobial therapy. The invasive capability of six S. aureus field isolates with different biofilm-forming profiles was compared in vitro using a bovine mammary epithelial cell line. This was further confirmed in primary cell cultures using fluorescent rRNA probes against S. aureus. The results suggest that S. aureus invasion levels are not related to biofilm formation.
Animals ; *Biofilms ; Cattle ; Cell Line ; Colony Count, Microbial/veterinary ; Epithelial Cells/microbiology ; Female ; In Situ Hybridization, Fluorescence ; Mastitis, Bovine/*microbiology ; Portugal ; Staphylococcal Infections/*veterinary ; Staphylococcus aureus/classification/genetics/immunology/*physiology ; Virulence Factors/i

In this study, the association between virulence genotypes and phylogenetic groups among Escherichia (E.) coli isolates obtained from pet dogs and cats with cystitis was detected, and fingerprinting methods were used to explore the relationship among strains. Forty uropathogenic E. coli (UPEC) isolated from dogs (n = 30) and cats (n = 10) in Italy were analysed by polymerase chain reaction (PCR) for the presence of virulence factors and their classification into phylogenetic groups. The same strains were characterized by repetitive extragenic palindromic (REP)- and enterobacterial repetitive intergenic consensus (ERIC)-PCR techniques. We found a high number of virulence factors such as fimbriae A, S fimbriae (sfa) and cytotoxic necrotizing factor 1 (cnf1) significantly associated with phylogenetic group B2. We demonstrated a high correlation between alpha-hemolysin A and pyelonephritis C, sfa, and cnf1 operons, confirming the presence of pathogenicity islands in these strains. In addition, UPEC belonging to group B2 harboured a greater number of virulence factors than strains from phylogenetic groups A, B1, and D. REP- and ERIC-PCR grouped the UPEC isolates into two major clusters, the former grouping E. coli strains belonging to phylogenetic group B2 and D, the latter grouping those belonging to groups A and B1. Given the significant genetic variability among the UPEC strains found in our study, it can be hypothesized that no specific genotype is responsible for cystitis in cats or dogs.
Animals ; Bacterial Proteins/analysis ; Bacterial Toxins/analysis ; Cat Diseases/microbiology ; Cats ; Cystitis/*microbiology ; Dog Diseases/microbiology ; Dogs ; Escherichia coli Infections/complications/microbiology/*veterinary ; Escherichia coli Proteins/analysis ; Female ; Genetic Variation ; Hemolysin Proteins/analysis ; Italy ; Male ; Operon ; Phylogeny ; Polymerase Chain Reaction ; Pyelonephritis/*microbiology ; Uropathogenic Escherichia coli/classification/*genetics/i ; Virulence Factors/*genetics