Streptococcus agalactiae is not always an obligate intramammary pathogen: Molecular epidemiology of GBS from milk, feces and environment in Colombian dairy herds
Bibliographic record
Abstract
For many years Streptococcus agalactiae has been considered an obligate intramammary and strictly contagious pathogen in dairy cattle. However, recent reports of S. agalactiae isolation from extramammary sources have contradicted that premise. To gain further insight into the epidemiology of S. agalactiae infection in cattle, we examined its distribution and heterogeneity of strains in bovine milk, bovine feces, and the environment in Colombian dairy farms. First, a longitudinal study was conducted at herd level in 152 dairy herds. Bulk tank milk samples from each herd where collected twice a month for six months. A follow-up study with a cross sectional design at the cow level was conducted in a subset of 25 farms positive for S. agalactiae. Cow-level milk samples from 1712 lactatting cows and 1545 rectal samples were collected, as well as 120 environmental samples. Samples were used for S. agalactiae detection and genotyping using Multi Locus Sequence Typing. Results showed sporadic rather than repeated isolation of S. agalactiae from bulk tank milk in 40% of the positive herds, challenging the idea that S. agalactiae is a highly contagious pathogen causing chronic infections. S. agalactiae was isolated from rectal or environmental samples in 32% and 12% of cross-sectional study farms, respectively, demonstrating that the bacteria can survive in extramammary sources and that S. agalactiae is not an obligate intramammary pathogen. The same strain was isolated from rectal and bulk tank milk samples in eight farms, suggesting that fecal shedding is frequent, and contributes to the presence of S. agalactiae in bulk tank. High within-herd heterogeneity of strains was found, which is distinct from the situation in developed dairy industries. These new epidemiological findings should be considered to adjust surveillance and control recommendations for S. agalactiae.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".