Mohammad Mehdi Soltan-Dallal - Dept. of Food Microbiology, School of Health, Tehran University of Medical Sciences, Tehran, Iran
Zahra Rajabi - Food Microbiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
Sara Sharifi Yazdi - School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Parisa Torabi-Bonab - Food Microbiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
Alireza Monadi Sefidan - Dept. of Medical Laboratory Sciences, Faculty of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran
Sina Sharifi Yazdi - School of Medicine, Tehran University of Medical Sciences, Tehran, Iran

Background and Objective: Breast milk contains nutrients such as carbohydrates, essential fatty acids, proteins, vitamins, minerals, and a source of communal bacteria with probiotic potential that is very effective in the prevention and treatment of neonatal infections. The aim of this study was the evaluation of probiotic properties of lactobacilli in breast milk and their inhibitory effect on pathogenic bacteria of the gastrointestinal tracts. Materials and Methods: In a cross-sectional descriptive study, during ۱۰ months from January to October ۲۰۱۸, ۱۰۰ breast milk samples were collected by referring to health centers after isolation. Lactobacilli strains were evaluated based on morphological characteristics, catalase, and hot staining tests, survival tests in acidic conditions, and bile salt tolerance to evaluate probiotic properties. Antibiotic resistance of probiotic strains and ability to inhibit pathogenic bacteria was evaluated by well method and growth inhibition zone. Results: ۱۲۲ lactobacilli belonging to ۱۲ species were identified from ۱۰۰ samples of breast milk by phototypical methods. The predominant species belonging to casei and other lactobacilli were Fermentum, Plantarum, and Gasseri, respectively.The highest antibiotic resistance was related to vancomycin (۶۳.۱۵%). The ۳ isolates L۴, L۱۴ and L۱۶ were able to strongly inhibit all the studied gastrointestinal pathogens. Conclusion: Breast milk is a rich source of beneficial probiotic lactobacilli, which can be useful in breast milk for infants who are not breastfed to prevent neonatal infections.

Breast milk, Lactobacillus, Probiotic, Inhibitory effect