Characterization of Streptococcus lutetiensis isolated from clinical mastitis of dairy cows

Abstract

Streptococcus lutetiensis, previously termed Streptococcus bovis type II/1, has rarely been associated with bovine mastitis. The objectives of this work were to characterize the molecular diversity, antimicrobial resistance profiles, virulence genes of Strep. lutetiensis (n = 37) isolated from bovine clinical mastitis, as well as its pathogenic effects in a murine mastitis model. Genetic relationships of isolates were determined by random amplified polymorphic DNA (RAPD)-PCR, virulence genes were detected by PCR. Antimicrobial susceptibility testing was carried out by broth microdilution technique. The pathogenic effects of Strep. lutetiensis were studied with 2 infection models: bovine mammary epithelial cells cultured in vitro and murine mammary infection in vivo. Streptococcus lutetiensis isolates were clustered into 5 RAPD-types (A-E), with a dominant type A representing 84% of isolates. Eighteen (49%), 16 (43%), and 9 (24%) isolates were resistant to ceftiofur, tetracycline, and erythromycin, respectively. Prevalence of multidrug resistance (resistant to ≥3 classes of antimicrobials) was 24% (9/37). The most prevalent virulence genes were bca (100%), speG (100%), hly (97%), scpB (95%), and ssa (95%). There was no difference between isolates from mild and moderate cases of bovine mastitis in prevalence of virulence genes. Streptococcus lutetiensis rapidly adhered to and subsequently invaded (1 and 3 h after infection, respectively) bovine mammary epithelial cells, resulting in elevated lactate dehydrogenase release (4 h after infection). Edema and hyperemia were observed in challenged mammary glands and bacteria were consistently isolated at 12, 24, and 48 h after infection. In addition, numerous neutrophils migrated into gland alveoli and interstitium of infected mammary tissue. We concluded that Strep. lutetiensis had potential to spread within a dairy herd and good adaptive ability in bovine mammary cells or tissue, which are generally characteristics of a contagious mastitis pathogen.

The Role of Streptococcus spp. in Bovine Mastitis

“…S. canis, S. equinus , and S. lutetiensis are rarely associated with bovine mastitis and were diagnosed in approximately <1% of all streptococcal infections [ 27 , 28 , 29 ]. For the streptococcal species rarely inducing bovine mastitis, reservoirs and risk factors are largely unknown.…”

“…Virulence factors for S. canis and S. equinus are rarely described. For S. lutetiensis known virulence factors are: hemolysin (Hly), α C protein (Bca), superantigen proteins, and C5a peptidase (ScpB) [ 29 ].…”

The first report and biological characteristics ofHelcococcus ovisisolated from clinical bovine mastitis in a Chinese dairy herd

“…Bovine mastitis is predominantly caused by bacteria, therefore, antimicrobials is extensively applied to mastitis prevention and treatment (17), which raised the concern of AMR that threatened the health of human beings (20). In our research study, the four isolates of H.ovis were only resistant to daptomycin, and one of isolates were intermediary to tetracycline and enrofloxacin, which were applied to bovine mastitis.…”

“…successfully used to assess bacterial infection and tissue damage (17). The murine model of H.ovis may improve our research on the correlation between this bacteria and bovine mastitis, the drug effect applied to clinical trials as well as the relationship among bacteria, bovine immune response and lactation (22).…”

“…Pregnant (20 d of gestation) 6-8-wk-old SPF BALB/c mice (SiPeiFu Laboratory Animal Technology, Beijing, China) were used to determine the pathogenic role of H.ovis during intramammary infection, as described (17). On the third day after parturition, mice were anesthetized with intramuscular injection of 50 mg/kg Zoletil 50 (Virbac, Carros, France).…”