Probiotics and Their Effect on Pathogenic Gram-Positive and Gram-Negative Bacteria: A Review

Background: There are more than four known strains of Lactobacillus bacteria, which have the ability to inhibit and kill antibiotic-resistant bacteria, especially Staphylococcus aureus and Pseudomonas aeruginosa. This is because it possesses specific mechanisms such as the production and formation of enzymes, acetaldehyde, organic acids, bacteriocins, H2O2, etc. Pathogenic bacteria are identified by their morphological characteristics on differential culture media and their ability to ferment lactose and produce mucus and hemolysin. Isolates are diagnosed through biochemical tests with three main tests: catalase enzyme production, oxylase fermentation test, and coagulase test, while molecular diagnosis is performed by using PCR tests and VITEK2 technology. Results: The antibiotic-resistant bacteria have the ability to have virulence genes such as coa, nuc, fimH, hlg, and hla, to name a few, which are widespread in Staph. aureus bacteria, and the hlyA and fimH genes belong to Gram-negative bacteria. Lactobacillus bacteria can bind to the host's living tissue cells via adhesion proteins and prevent Staph. aureus bacteria from infecting the host's tissues by up to more than 80%, thus maintaining the environmental and life balance within the host and reducing the formation of anti-inflammatory cytokines such as interleukin in particular (IL17), it was also found that Lactobacillus in general has the ability to inhibit and kill antibiotic-resistant Gram-negative bacteria (MDA). Conclusions: Lactobacillus strains can prevent multidrug-resistant (MDR) Gram-positive and Gram-negative bacteria from spreading and multiplying by secreting antigens, proteins, and acidic compounds that disrupt the processes of adhesion of pathogenic bacteria to the living tissues of the host.