Characterization of an Enterococcus faecium strain in a murine mastitis model

Abstract

Aim The aim of the study was to characterize phenotypically and genotypically Enterococcus faecium strains collected from bovine mastitis milk and to evaluate one of them for its virulence in a murine mastitis model. Methods and Results A total of five E. faecium isolates were collected from cows with subclinical mastitis. EF‐7A showed resistance to antibiotics tested, it presented alpha haemolysin and did not present gelatinase activity. It yielded cyA, efafm and gelE1 genes and it could be characterized as a moderate biofilm producer. It was able to internalize in MAC‐T cells and 1×108 colony forming unit ml‐1 was able to establish an intramammary infection in mice. The strain could be recovered from liver, kidney and blood samples. RAPD profiles showed different bands with respect to the inoculated strain. Histopathology analyses showed different grades of polymorphonuclear neutrophils infiltration in mammary glands. Conclusion This is the first report that studied E. faecium strain in a lactating mouse model of mastitis and showed that the experimental inoculation was able to stimulate an inflammatory response resulting in mastitis. Results contribute to a better understanding of intramammary infections caused by E. faecium. Significance and Impact of the Study This investigation shows that mice represent a valuable model for the study of the mastitis pathogenesis caused by E. faecium considering the high costs of using cows for mastitis research.

Infective mastitis due to bovine‐associated Streptococcus dysgalactiae contributes to clinical persistent presentation in a murine mastitis model

“…The bacteria could not be removed from mammary glands over 10 days. The number of Enterococcus faecium strains recovered from the mammary gland had a strong decrease in the bacterial load was reported at 1 day, followed by a slight increase at 2 days PI (Montironi et al, 2020). A murine mastitis model of Aerococcus viridans using BALB/c mice and reported that the pathogen was able to colonize the mammary gland after the intramammary inoculation with 2 × 10 3 CFUs at 9 days PI (Liu et al., 2019).…”

Isolation, identification, and pathogenicity analysis of Staphylococcus devriesei associated with subclinical bovine mastitis

“…As a G + endotoxin, LTA plays an important role in bio lm formation and bacterial viscosity, which is conducive to the establishment and spread of pathogen infection, and is a key endotoxin to induce immune response [31]. The D-Ala modi cation of LTA is mainly considered a virulence factor that promotes adhesion, colonization, invasion, activation of the immune response, in ammation, and abscess formation [22,32].…”

Capacity of adherence, invasion and intracellular survival of Streptococcus uberis biofilm-forming strains

“…At the same time, the ability of S. uberis strains to internalize was assayed according to Montironi et al (2019). Following incubation with bacteria, a treatment with gentamicin (100 mg ml −1 ) during 1 h at 37°C in 5% CO 2 was performed to kill extracellular bacteria.…”