Abstract:
Executive Summary
Milk is harboring both pathogenic and beneficial bacteria. This study aimed to identify and
screen potent lactic acid bacteria having antimicrobial activity against multidrug resistant
food borne zoonotic pathogens. The 100 milk samples of cow were aseptically collected
from 10 randomly selected dairy farms of Dhaka City of Bangladesh. The collected milk
samples were then processed and cultured on to selective media. The isolated
microorganisms were identified based on staining, motility, cultural and biochemical
properties according to standard laboratory methods. PCR confirmation of Staphylococcus
species were performed by targeting the primers of 16S rRNA. The isolated bacteria were
also subjected to characterize their antibiotic sensitivity. Antimicrobial potency (AMP) of
the isolated Lactic Acid Bacteria (LAB) were screened by agar well diffusion test. Among
100 milk samples, 56% milk samples were reported as positive for Staphylococcus species,
followed by Escherichia coli (23%), Klebsiella spp. (19%), and Salmonella spp. (9%) (p
<0.001). On the other hand, 143 pathogenic bacteria were isolated and identified from the
milk samples inspected of which 49.65% were Staphylococcus species, 25.17% were
Escherichia coli, 18.88% were Klebsiella spp., and 6.29% were Salmonella spp. In terms of
LAB, 184 isolates were identified from 100 milk samples. Multidrug resistant (MDR)
property was observed in around 90% of the isolates (p<0.001). Among them, 100% of the
Escherichia coli and Klebsiella spp. showed MDR properties followed by Staphylococcus
spp. (81.69%), and Salmonella spp. (77.78%). Most of the isolates showed their resistance
against ampicillin, amoxicillin, and tetracycline. It was revealed that 11 LAB showed AMP
against Salmonella spp. Overall, the production of appropriate probiotics and postbiotics
from LAB containing AMP can help to lower the MDR milk-borne pathogenic bacterial
infection.
