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Published on: February 9, 2011
Trace Element Changes in Goat Milk Following Experimentally Induced Intramammary Infection With Biofilm Positive and
M Ghari1, M Heidarpour1, M Ghaemi2
1Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.
Background:
Trace elements in milk provide valuable information about mammary gland health and immune response. The biofilm-forming ability of Staphylococcus aureus is known to contribute to persistent and chronic mastitis infections.
Objectives:
This study aimed to compare changes in milk trace element concentrations following experimental intramammary infection with biofilm-positive and biofilm-negative strains of S. aureus in goats.
Methods:
Nine healthy lactating goats (native Iranian breed, 1-5 years old) were allocated to two groups and inoculated intracisternally in one udder half with either biofilm-positive (n = 5) or biofilm-negative (n = 4) strains of S. aureus (103 CFU/mL). The strains were isolated from bovine mastitis and confirmed by polymerase chain reaction (PCR) amplification of the nuc. Ceftiofur was administered for treatment after confirmation of infection. Ceftiofur was chosen because both strains were sensitive to this antibiotic and previous research has shown Ceftiofur to be effective against both biofilm-positive and biofilm-negative S. aureus isolates. Milk samples were collected immediately before challenge (T0), at 6 (T1), 12 (T2), 24 (T3), 36 (T4), 48 (T5) and 72 (T6) hours post-challenge, immediately prior to treatment (T7), and at 1 (T8), 7 (T9) and 14 (T10) days post-treatment. Concentrations of copper, calcium, selenium, zinc, magnesium, potassium, sodium and phosphorus were determined using inductively coupled plasma optical emission spectrometry (ICP-OES).
Results:
The milk calcium concentration at T2 and T4 was significantly higher in the biofilm-positive group than that in the biofilm-negative group (p < 0.05). The amount of milk selenium at T4 and T10 was significantly higher in the biofilm-positive group than that in the biofilm-negative group (p < 0.05). The milk potassium and phosphorous levels at T7 were significantly higher in the biofilm-positive group than that in the biofilm-negative group (p < 0.05).
Conclusions:
Biofilm-positive strains of S. aureus induced a greater secretion of certain trace elements (particularly calcium, selenium, potassium and phosphorus) into goat milk compared with biofilm-negative strains. These findings are consistent with the hypothesis that biofilm-forming strains cause more extensive mammary epithelial damage and barrier dysfunction. These alterations may be indicative of increased mammary epithelial permeability and may also lead to compromised local immunity, allowing for persistent mastitis development by biofilm positive strains.
