Microbiota of Cow’s Milk; Distinguishing Healthy, Sub-Clinically and Clinically Diseased Quarters

Abstract

The objective of this study was to use pyrosequencing of the 16S rRNA genes to describe the microbial diversity of bovine milk samples derived from clinically unaffected quarters across a range of somatic cell counts (SCC) values or from clinical mastitis, culture negative quarters. The obtained microbiota profiles were used to distinguish healthy, subclinically and clinically affected quarters. Two dairy farms were used for the collection of milk samples. A total of 177 samples were used. Fifty samples derived from healthy, culture negative quarters with a SCC of less than 20,000 cells/ml (group 1); 34 samples derived from healthy, culture negative quarters, with a SCC ranging from 21,000 to 50,000 cells/ml (group 2); 26 samples derived from healthy, culture negative quarters with a SCC greater than 50,000 cells/ml (group 3); 34 samples derived from healthy, culture positive quarters, with a SCC greater than 400,000 (group 4, subclinical); and 33 samples derived from clinical mastitis, culture negative quarters (group 5, clinical). Bacterial DNA was isolated from these samples and the 16S rRNA genes were individually amplified and pyrosequenced. All samples analyzed revealed great microbial diversity. Four bacterial genera were present in every sample obtained from healthy quarters (Faecalibacterium spp., unclassified Lachnospiraceae, Propionibacterium spp. and Aeribacillus spp.). Discriminant analysis models showed that samples derived from healthy quarters were easily discriminated based on their microbiota profiles from samples derived from clinical mastitis, culture negative quarters; that was also the case for samples obtained from different farms. Staphylococcus spp. and Streptococcus spp. were among the most prevalent genera in all groups while a general multivariable linear model revealed that Sphingobacterium and Streptococcus prevalences were associated with increased 10 log SCC. Conversely, Nocardiodes and Paenibacillus were negatively correlated, and a higher percentage of the genera was associated with a lower 10 log SCC.

Technical note: A pilot study using a mouse mastitis model to study differences between bovine associated coagulase-negative staphylococci

“…The absence of coagulase production in transformed S. aureus remarkably diminished its intramammary virulence in mice (Jonsson et al, 1985); this most likely also relates to the minimal virulence of CNS in mice at first, as observed in the current study. The lower pathogenicity of the CNS strains compared with S. aureus explains the high prevalence of the former pathogens in the milk of clinically healthy cows and their less detrimental effects during bovine mastitis (Pate et al, 2012;Braem et al, 2013;Oikonomou et al, 2014).…”

Longitudinal metagenomic profiling of bovine milk to assess the impact of intramammary treatment using a third-generation cephalosporin

“…For instance, commensal bacteria present in human milk inhibit proliferation of Staphylococcus aureus 7, which is also a pathogen commonly associated with mastitis in dairy cows8. Considering that mastitis possibly reflects a dysbiosis within the mammary gland91011, a detailed assessment of the milk microbiome during active stages of clinical disease, spontaneous recovery, treatment and post-treatment is essential to further elucidate this pathological condition.…”

Farm animal health : progress, problems and perspectives

“…Studying the relationship between the mammary microbiome and the somatic cell count of the milk resulted in a negative correlation with the amount of bacteria of the paenibacillus genus. Indicating that more of the paenibacillus bacteria resulted in a healthier gland (Oikonomou et al 2014). The healthy microbiome of the mammary gland shows an enormous amount of diversity while mastitis affected glands show an overgrowth with pathogenic bacteria and a substantial loss of bacterial diversity.…”