In this study, we conducted a whole-genome analysis of the Lacticaseibacillus paracasei subsp. paracasei 2LB isolated from Kazakh traditional fermented milk (koumiss) to identify genes associated with the safety and probiotic potential of the strain. A comparative genomic analysis of the core and pan-genome of L. paracasei 2LB was performed. Functional annotation revealed the presence of genes putatively involved in metabolism, genetic information processing, and cellular processes. In terms of safety parameters, the stability of its genetic material, the absence of the ability to synthesize virulence factors, and genes responsible for antibiotic resistance were characterized. Also, in vitro studies of the L. paracasei 2LB strain showed resistance to stress factors and antimicrobial activity, and the presence of coding sequences encoding adhesion factors, bacteriocins, bile salts, pH, cold and heat shock, and osmotic stress was observed through genomic analysis. These results indicate that the L. paracasei 2LB strain is a potential probiotic candidate and demonstrate that whole-genome analysis is a useful method for assessing the quality and safety of probiotics.

Staphylococcus aureus (S. aureus) is an opportunistic pathogen that causes a range of diseases, from mild skin and soft tissue infections and food poisoning to serious conditions such as pneumonia, endocarditis, sepsis, and hospital-acquired infections. Due to the aggressive nature of the disease, limitations of existing treatments, and the spread of antibiotic-resistant strains, the development of alternative strategies to combat bacterial infections has progressed faster than the development of new antibiotics. In this review, we analyze the epidemiological situation of morbidity and mortality associated with S. aureus infection, as well as antimicrobial resistance of this organism on a global scale. We reviewed the pathogenesis and virulent factors of S. aureus, their mechanisms of antibiotic resistance, and the importance of diagnosing staphylococcal infections to ensure timely intervention. This review also discusses the latest approaches to combating antibiotic resistance in Staphylococcus aureus, including preventive and therapeutic antimicrobial strategies. Such methods as the use of bacteriophages in treatment, antimicrobial peptides, probiotic microorganisms and their metabolites, and the use of inhibitors to suppress bacterial communication are considered.

An imbalance of the gut microbiota may lead to the development of many chronic diseases; therefore, restoring its normal composition is considered one of the most pressing issues today. Probiotic therapy is being extensively studied as a scientifically validated and safe method for effectively regulating the intestinal biocenosis. In this context, the therapeutic activity of a dry powder form of the studied probiotic preparation was evaluated in an in vivo model of antibiotic-induced gut dysbiosis. White outbred laboratory rats of both sexes, weighing 200–300 g, were used in the study. Fecal samples were collected on days 1, 8, 14, and 18 of the experiment for microbiological analysis of the gut microbiota. Animals were divided into the following groups: control (positive control – saline) and experimental group (probiotic 1×10⁹ CFU/g). For the microbiological analysis of fecal contents, inoculations were performed on eight selective nutrient media. During the dysbiosis phase, the control group showed a significant increase in conditionally pathogenic microorganisms: Clostridium spp. and Salmonella spp. – 9.75±0.31 lg CFU/g, Staphylococcus spp. – 8.13±0.27 lg CFU/g, Enterococcus spp. – 8.58±0.32 lg CFU/g, Klebsiella spp. and Enterobacter spp. – 9.03±0.48 lg CFU/g, and Escherichia coli – 8.46±0.45 lg CFU/g. At the end of the treatment phase, the experimental group showed a notable reduction in these values: Clostridium spp. – 7.91±0.34 lg CFU/g, Staphylococcus spp. – 6.07±0.30 lg CFU/g, Klebsiella spp. – 5.33±0.56 lg CFU/g, E. coli – 6.92±0.44 lg CFU/g. Additionally, the number of beneficial Lactobacillus spp. increased from the initial level of 8.57±0.37 lg CFU/g to 9.00±0.50 lg CFU/g. These findings demonstrate the efficacy of the new lactobacilli-based probiotic in correcting antibiotic-induced intestinal dysbiosis and in restoring microbial balance.