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Effect of antibiotics and vehicles on bovine mammary polymorphonuclear leukocyte morphologic features, viability, and
Abstract:
Effects of antibiotics and antibiotic vehicles on polymorphonuclear leukocytes (PMNL) isolated from bovine mammary glands were studied in vitro. Amikacin, dicloxacillin, erythromycin, gentamicin, lincomycin, nitrofurantoin, novobiocin-penicillin, polymyxin B, rifampin, tetracycline, or tiamulin was added to culture medium at 1 mg/ml and chloramphenicol was added at 4 mg/ml. Drug concentrations were equivalent to those detected in milk immediately after injection into the mammary gland. Vehicles included mineral oil and peanut oil, each at a dilution of 1:100 in culture medium. The PMNL morphologic features, viability, and phagocytic activity were evaluated. In comparison with the phosphate-buffered saline solution (PBSS) control, significant (P less than 0.05) alterations in normal cell morphologic features were observed in PMNL cultured with tetracycline, nitrofurantoin, erythromycin, polymyxin B, rifampin, novobiocin-penicillin, chloramphenicol, tiamulin, or peanut oil. Viabilities of PMNL cultured with chloramphenicol, novobiocin-penicillin, or tiamulin were significantly (P less than 0.05) reduced when compared with those of PBSS controls. Addition of Staphylococcus aureus to culture medium enhanced morphologic alterations and reduced viabilities of PMNL. Phagocytosis of S aureus by PMNL was significantly (P less than 0.05) depressed in medium containing novobiocin-penicillin, amikacin, rifampin, chloramphenicol, tiamulin, or peanut oil in comparison with that of PMNL incubated in PBSS.
Insights
Certain antibiotics and oils negatively impact bovine polymorphonuclear leukocytes (PMNL), affecting their morphology, viability, and ability to fight Staphylococcus aureus infections.
Area of Science:
- Veterinary Immunology
- Bovine Mastitis Research
- Antimicrobial Efficacy
Background:
- Polymorphonuclear leukocytes (PMNL) are crucial for bovine mammary gland defense against infection.
- Antibiotic treatments for mastitis can influence the immune function of PMNL.
- Understanding these effects is vital for optimizing mastitis treatment strategies.
Purpose of the Study:
- To investigate the in vitro effects of various antibiotics and their vehicles on bovine PMNL.
- To assess the impact on PMNL morphology, viability, and phagocytic activity.
- To determine if these effects are exacerbated by the presence of Staphylococcus aureus.
Main Methods:
- Bovine mammary gland PMNL were isolated and cultured in vitro.
- Antibiotics (amikacin, dicloxacillin, erythromycin, etc.) and vehicles (mineral oil, peanut oil) were added to culture media at relevant concentrations.
- PMNL morphology, viability, and phagocytosis of S. aureus were evaluated.
- Phosphate-buffered saline solution (PBSS) served as the control.
Main Results:
- Tetracycline, nitrofurantoin, erythromycin, polymyxin B, rifampin, novobiocin-penicillin, chloramphenicol, tiamulin, and peanut oil caused significant morphologic alterations in PMNL.
- Chloramphenicol, novobiocin-penicillin, and tiamulin significantly reduced PMNL viability.
- The presence of S. aureus worsened morphologic changes and reduced PMNL viability.
- Novobiocin-penicillin, amikacin, rifampin, chloramphenicol, tiamulin, and peanut oil significantly depressed S. aureus phagocytosis by PMNL.
Conclusions:
- Several antibiotics and oil-based vehicles used in bovine mastitis treatment can impair critical functions of PMNL.
- These impairments include reduced cell viability and phagocytic capacity, potentially compromising the cow's immune response.
- Further research is needed to develop treatments that minimize negative impacts on bovine innate immunity.