Antagonistic and antibacterial activity of Lactobacillus rhamnosus HN001 and Lactobacillus acidophilus La-14 included in the oral probiotic

BACKGROUND: A microbial imbalance in the vaginal biotope leads to the development of vaginal infections and is associated with urinary tract infections. The ineffectiveness of the therapy and the frequent recurrence of these infections are important reasons for searching for alternative treatment strategies. A progressive solution to this issue has been the use of oral probiotics with a targeted effect on the intestinal and vaginal microflora. AIM: The aim of this study was to evaluate the antagonistic and antibacterial activity of the probiotic strains Lactobacillus rhamnosus HN001 and Lactobacillus acidophilus La-14, which are the components of the oral probiotic, against opportunistic microorganisms of intestinal origin, while assessing the sensitivity of these strains to antimicrobial drugs. MATERIALS AND METHODS: The probiotic strains Lactobacillus rhamnosus HN001 and Lactobacillus acidophilus La-14 included in the oral probiotic Duogynal® were cultivated and the grown colonies were identified using the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry method (Bruker Daltonics GmbH Co., Germany). To study the antagonism of the probiotic strains of lactobacilli and opportunistic pathogenic microorganisms, the following 11 clinical isolates were collected: Escherichia coli (two isolates), Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter asburiae, Proteus mirabilis, Citrobacter freundii, Staphylococcus aureus, Enterococcus faecalis, Streptococcus agalactiae, and Candida albicans. To assess the sensitivity of the probiotic strains to antimicrobial drugs, the Gram Positive AST panel (Autobio Diagnostics Co., Ltd, China) was used. RESULTS: When the microorganisms were co-cultivated with the probiotic lactobacilli (Lactobacillus rhamnosus HN001 and Lactobacillus acidophilus La-14), we noted a decrease in pH and the death of opportunistic microorganisms such as Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter asburiae, Proteus mirabilis, Citrobacter freundii, Staphylococcus aureus, Enterococcus faecalis, and Streptococcus agalactiae, as well as yeast-like fungi Candida albicans. When studying antibiotic resistance, it was found that the both strains of lactobacilli were resistant to ampicillin, vancomycin, daptomycin, clindamycin, linezolid, moxifloxacin, nitrofurantoin, oxacillin, oritavancin, penicillin, rifampin, teicoplanin, tigecycline, trimethoprim/sulfamethoxazole, cefoxitin, ceftarolin, and ciprofloxacin. CONCLUSIONS: The oral probiotic, which contains a combination of two lactobacilli (Lactobacillus rhamnosus HN001 and Lactobacillus acidophilus La-14), has pronounced antagonistic activity against opportunistic microorganisms. These strains are resistant to most antibacterial drugs used in widespread clinical practice, which may be the basis for recommending the use of this probiotic drug together with prescribed antibiotics for prevention of vaginal or intestinal dysbiosis.