Microbial agents in macroscopically healthy mammary gland tissues of small ruminants

Abstract

BackgroundHealth of mammary glands is fundamental for milk and dairy products hygiene and quality, with huge impacts on consumers welfare.MethodsThis study aims to investigate the microbial agents (bacteria, fungi and lentiviruses) isolated from 89 macroscopically healthy udders of regularly slaughtered small ruminants (41 sheep, 48 goats), also correlating their presence with the histological findings. Multinomial logistic regression was applied to evaluate the association between lesions and positivity for different microbial isolates, animal age and bacteria.ResultsTwenty-five samples were microbiologically negative; 138 different bacteria were isolated in 64 positive udders. Coagulase-negative staphylococci were the most prevalent bacteria isolated (46.42%), followed by environmental opportunists (34.76%), others (10.14%) and pathogens (8.68%). Most mammary glands showed coinfections (75%). Lentiviruses were detected in 39.3% of samples. Histologically, chronic non-suppurative mastitis was observed in 45/89 glands, followed by chronic mixed mastitis (12/89) and acute suppurative mastitis (4/89). Only 28 udders were normal. Histological lesions were significantly associated with the animal species and lentiviruses and coagulase-negative staphylococci infections. Goats had significantly higher risk to show chronic mixed mastitis compared to sheep. Goats showed a significantly lower risk (OR = 0.26; 95% CI [0.06–0.71]) of being infected by environmental opportunists compared to sheep, but higher risk (OR = 10.87; 95% CI [3.69–37.77]) of being infected with lentiviruses.DiscussionThe results of the present study suggest that macroscopically healthy glands of small ruminants could act as a reservoir of microbial agents for susceptible animals, representing a potential risk factor for the widespread of acute or chronic infection in the flock.

Characterization of Coagulase Negative Staphylococci Isolated from Dairy Goats in Germany

“…This ratio is similar to that reported in USA in which the NAS prevalence in goat mastitis ranged between 63.5 and 75% as reported by Tomita et al [33] and Gaucher, etc., respectively. However, in opposite to the situation in USA and our findings, NAS could be isolated from up to 95.9% of mastitic goat cases and even from 46.4% of healthy udder tissues in Italy [8,16] .…”

“…Five isolates reacted negatively with the PCR and therefore were excluded from both tables (Table 3 and 4). These five isolated showed the antibiotic resistance profile R10 (n = 4) and R13 (n = 1) and were addressed to be Micrococci years, NAS replaced coagulase positive Staphylococci as a major mastitis pathogen in goats in many countries worldwide [16,30] . This may be attributed to many factors such as the vaccinal stress due to the use of anti S. aureus mastitis vaccines which could restrict the ability of the S. aureus strains to multiply and spread [31,32] .…”

Does Small Ruminant Lentivirus Infection in Goats Predispose to Bacterial Infection of the Mammary Gland? A Preliminary Study

“…The health and functionality of the mammary gland are important factors in the welfare of dairy animals and milk production, as well as in dairy product quality and profitability for farmers and the dairy industry. Mastitis is typically caused by bacterial, fungal, or algal infections, and usually manifests as an increase of milk somatic cell count (SCC) [1]; however, pathogenic bacteria, including Staphylococcus aureus, have been detected in about 20% of goat milk samples with SCC < 1 × 10 6 /mL [2].…”

Association between polymorphism of ABCG2 gene and somatic cell count in Czech dairy sheep breeds

“…It is an inflammatory disease of the mammary gland, which is manifested by an increased number of somatic cells in milk (18). Inflammation of the mammary gland is caused mainly by bacteria -the most prevalent are coagulase-negative staphylococci (22,24). Mastitis has economic implications related to the costs of treatment, premature slaughter (17), reduced growth of lambs and their mortality caused by reduced milk production, and a reduction in the price of milk due to its lower quality (24).…”

“…Inflammation of the mammary gland is caused mainly by bacteria -the most prevalent are coagulase-negative staphylococci (22,24). Mastitis has economic implications related to the costs of treatment, premature slaughter (17), reduced growth of lambs and their mortality caused by reduced milk production, and a reduction in the price of milk due to its lower quality (24). Subclinical mastitis negatively influences milk yield, and the low milk yield (especially with a reduced lactose concentration) is associated with a low cheese yield and cheese quality (22).…”