Abstract:
Several food-borne outbreaks caused by Staphylococcus aureus intoxications have been associated with consumption of contaminated milk and its products. Lactic acid bacteria (LAB) are involved in fermentation of milk which act as a potential food preservative due to their antagonistic activity against many food borne pathogens. This study therefore reveals the inhibitory effect of LAB against enterotoxin producing Staphylococcus aureus. Total samples of 250 powdered milk and other dairy products were collected within major Cities in Southwest of Nigeria including, Akure, Ile-Ife, Abeokuta, Ibadan, Ado-Ekiti. Species of Staphylococcus and Lactobacillus were isolated from powdered milk and milk products using standard microbiological methods. The microorganisms were identified using biochemical tests and molecular techniques. Screening of enterotoxin-producing S. aureus was carried out using biochemical methods and confirmed with molecular tools. Antibacterial activity of LAB against enterotoxin-producing S. aureus was ascertained using agar well diffusion. Healthy albino rats were challenged with enterotoxin-producing S. aureus and treated with Lactobacillus species. Hematological and histological study of albino rats were carried out. LAB inhibited the growth of both non-enterotoxin and enterotoxin-producing S. aureus with zones of inhibition ranged from 12.60 to 23.30mm. The highest zone (23.30mm) of inhibition was recorded when synergistic combination of LAB was done. The infected albino rats loss appetite and led to decrease in the body weight but when LAB was administered appetite was restored which led to increase in the body weight of the treated albino rats. There was reduction in enterotoxin-producing S. aureus in the faecal count of the treated albino rat. PCV of the treated group and control albino rats was within which 38-42% while the untreated group had low PCV of 30%. MCV of the untreated albino was excessively high (above 125 fl) while the treated and control falls within normal range (80-120 fl). Histological study revealed that LAB was able to reverse the adverse effect caused by enterotoxin-producing S. aureus with the group having a normal histological structure with visible lesions in their liver and intestine. The antibacterial potential of LAB against enterotoxin-producing S. aureus confirmed that the organism can be used to antagonize the effect caused by enterotoxin-producing S. aureus.
