Efficacy of a Lactoferrin-Penicillin Combination to Treat β-Lactam-Resistant Staphylococcus aureus Mastitis
Bibliographic record
Abstract
The efficacy of intramammary (IM) treatments containing penicillin G (PG) alone or a combination of PG and bovine lactoferrin (bLF) was evaluated using a model of experimentally induced chronic bovine mastitis caused by a clinical isolate of Staphylococcus aureus highly resistant to beta-lactam antibiotics. First, we confirmed that this strain could cause mastitis and infection could not be cured with PG alone. In a second trial, chronic mastitis was induced in 19 late-lactating cows by injecting a low dose of Staph. aureus through the teat canal of all quarters. After 15 d, cows with stable infections in their 4 quarters had their mammary quarters randomly assigned, within cow, to 1 of 4 IM treatments as follows: 1) citrate buffer, 2) 100,000 IU of PG, (3) 1 g of bLF, or 4) 1 g of bLF + 100,000 IU of PG. Treatments were repeated twice a day for 5 d. A third trial was undertaken to investigate the effect of an extended therapy on chronic mastitis acquired in a previous lactation. One month before dry-off, 20 gravid cows regrouped by dates of calving were infected in their 4 quarters. Once infections were established, cows were dried off abruptly. After calving, aseptic milk samples were collected separately from all quarters for 4 wk to monitor infection. Mammary quarters from enrolled cows were then randomly assigned, within cow, to 1 of 2 treatments as follows: 1) 100,000 IU of PG or 2) 250 mg of bLF + 100,000 IU of PG. Treatments were administered IM twice a day for 7 d. For all trials, milk samples were taken to monitor bacterial concentration and somatic cell count. Bacteriological cure rate was determined using milk samples taken 3 and 4 wk after initiation of treatments. For the second trial, cure rate was null for control quarters, 11.1% for bLF, 9.1% for PG, and 45.5% for the bLF + PG combination. For cows infected in their previous lactation, cure rate was higher for the bLF + PG combination (33.3%) compared with PG alone (12.5%). In conclusion, bLF added to PG is an effective combination (i.e., 3- to 5-times higher cure rate) for the treatment of stable Staph. aureu infections highly resistant to beta-lactam antibiotics.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".