Lactobacilli - Probiotic as well as an Uncommon Pathogen – Current Status Regarding the “Two Sides of the Same Coin:” An Overview

Abstract Lactobacilli are nonsporing, lactic acid producing, anaerobic bacilli, classified under the phylum Firmicutes that form part of the normal flora in specific areas of the human body inclusive of the oral cavity, gastrointestinal tract, and the urogenital system. This genus, for instance contains Lactobacillus acidophilus , Lactiplantibacillus plantarum , Lacticaseibacillus rhamnosus , and others, when they are involved in the breakdown of glucose, they release lactic acid. It plays a major role in the production of fermented foods and in addition, it can serve as a probiotic which can be good to the host in that it can help in digestion, synthesis of vitamins, and can prevent colonization by pathogens. Lactobacilli are in association, although, in a commensal manner in large numbers during puberty and pregnancy and are also acidity maintainers, thereby preventing the pathogens to occupy the vaginal tract. They have also been declared to influence antiviral functions together with the suppression of virulence factors of pathogens based on recent studies. However, some categories of strains have been associated with life-threatening conditions such as endocarditis, meningitis, liver abscess, and bacteremia, particularly in immunocompromised clients. Regarding Lactobacilli , speciation has grown with methods such as MALDI-TOF, as it is faster and accurate than biochemical assays. Because their fermentative metabolism differs, they are grouped into the obligate homofermentative, facultative heterofermentative, and the obligate heterofermentative lactobacilli that assists in their identification and functionality. Lactobacilli being the probiotics are known to be safe and effective as endorsed by such bodies as the US Food and Drug Administration and European Food Safety Authority. Prebiotics are most effective in preterm infants and neonates where they help in strengthening the Gut barrier and Immunity. Thus, two probiotic strains like L . rhamnosus , and L . acidophilus have shown some positive impacts against different infections such as Helicobacter pylori , Clostridium difficile -associated diarrhea, and periodontitis. Nevertheless, one cannot disregard the possible pathogenicity of Lactobacilli as a number of strains are known to produce enzymes and organic acids which are hazardous to the human body. These examples of invasive infections stemming from strict regard for the use of probiotics only serve to enforce the prospect of heedful application of probiotics, especially to the vulnerable groups of people. Furthermore, diseases such as vaginal lactobacillosis are created to focus on the need for moderation in the consumption of probiotics. In summary, it can be seen that both, the roles and effects of Lactobacilli are twofold, as positive components with great potential for benefiting health as well as negative aspects that need further assessment.