Reference Lactobacillus strains as Potential Antimicrobial Agents Against Priority Pathogens with Different Levels of Drug Resistance

Abstract

Probiotics are beneficial microorganisms that can exert antibacterial activity against pathogenic bacteria. In this study, we evaluated the antibacterial activity of probiotics reference strains of, Lactobacillus acidophilus(LA, NCDC Accession No. 13), Lactobacillus casei(LC, NCDC Accession No. 17), and Lactobacillus plantarum(LP, NCDC Accession No. 20) against twelve pathogens, some of which are classified as High priority by the World Health Organization (WHO) due to their extensive antibiotic resistance. The probiotics were obtained from the National Collection of Dairy Cultures (NCDC); National Dairy Research Institute (NDRI), Karnal; India as reference strains. The pathogens were isolated from clinical samples and identified by Matrix-Assisted Laser Desorption Ionization Time-Of-Flight (MALDI-TOF) mass spectrometry, while their antibiotic resistance profiles were identified using VITEK®2. The antibacterial activity of the probiotics was measured by two standard methods (agar well diffusion and agar slab method). The zone of inhibition and the antagonistic activity of the probiotics were recorded and compared. All three probiotics exhibited antibacterial activity against all 12 pathogens, with varying degrees of inhibition and antagonism. The study demonstrated that lactobacilli strains from NDRI had shown to be effective in inhibiting the growth of WHO-priority pathogens.