Determination of the Lactic Acid Bacteria (LAB) as an alternative for probiotics and their inhibitory role against the pathogenic bacterial profile in the stool samples of newborns

Abstract

This study aimed to isolate, identify, and diagnose the pathogenic bacterial profile from the 150 stool samples of the newborns, represented by  75 of these samples (50 %) of healthy newborns and 75 samples from another group of newborns affected with diarrhea. The samples were then cultivated on  Mannitol salt agar (MSA), MacConkey agar (MA), and MRS agar within  37 º C for 24 hrs., which was followed by an evaluation of lactic acid bacteria (LAB) to detect the probiotics properties as well as the inhibitory role of the metabolites activity against the pathogenic isolates. The results of this study have shown that the bacterial isolates from the healthy newborn at 75 samples were at 82 isolates; they were distributed for LAB at 53, E.coli at 21, two of Staphylococcus aureus, one of Shigella sonnei and five isolates of Enterobacter cloacae. At the same time, the samples from diarrhea newborns were isolated from 93 bacterial isolates, distributed at 10 of LAB, 42 of E.coli, and 12 of Staph. aureus, 17 of S. sonnei and 12 isolates from E.chloacae. The LAB species appeared as Lactobacillus gasseri, Bifidobacterium bifidus, Lactobacillus acidophilus, and Lactobacillus casei at 21 (39.6%), 10 (18.8%), 10 (18.8%) and 12 (22.6%) respectively. The species of Lb. gasseri has been shown to act as probiotics and appeared to be the best at resisting bile salts and pH levels. The pathogenic isolates appeared to be resistant to most antibiotics, while the E.coli isolates were the most resistant, and the LAB appeared susceptible to all antibiotics used. In addition, the inhibitory activity of the  LAB isolates or its metabolites as probiotics against  E.coli isolates have been shown at a high range of zone inhibition diameters of  35mm. In conclusion, the data obtained from this study suggests that the microbial profile of the stool from the healthy newborn contains significantly a higher number of LAB compared with newborns affected with diarrhea, which is the last (LAB isolates) probiotic properties which could be leading to maintain the immune homeostasis of the body and improving the health status.