Synergistic Effect Between Two Bacteriocin-like Inhibitory Substances Produced by Lactobacilli Strains with Inhibitory Activity for Streptococcus agalactiae

Abstract

Group B streptococci (GBS) are bacterial species that colonize the vagina in pregnant women and as such may cause serious infections in neonates that passed through the birth channel. The objective of this work was to study the inhibitory activities produced by each bacteriocin-like inhibitory substance (BLIS) of Lactobacillus rhamnosus L60 and Lactobacillus fermentum L23, and the effects of the combined BLIS-es of these lactobacilli on GBS. The interactions between the BLIS-es were assessed by qualitative and quantitative methods on agar plates. The minimum inhibitory concentrations (MICs) and fractional inhibitory concentrations (FICs) were determined by a modification of the broth microdilution and checkerboard methods, respectively. Antibiotic susceptibilities of all S. agalactiae strains were assayed and the results of these tests were evaluated for statistical significance. A 7.5% of GBS isolates were recovered from 760 pregnant women and 91% of those strains were susceptible to each BLIS produced by L. fermentum, L. rhamnosus, and also to a mixture of them. The comparisons among the BLIS-es showed statistically significant differences, with a combination of the BLIS-es from the two Lactobacillus species being better than the BLIS of each one alone (P < 0.05) as GBS growth inhibitors. Synergistic activities between the BLIS-es were found on 100% of susceptible GBS strains, MICs ranges of BLIS of L23 and L60 were 80-160 and 160-320 UA ml(-1), respectively. By the checkerboard method, the BLIS-es combination showed synergistic effect on all sensitive strains tested, with values of FICs ranging from 0.131 to 0.218. The BLIS-es produced by these lactobacilli of vaginal origin were able to inhibit S. agalactiae isolates. The results indicate that these strains may have probiotic potential for the control of GBS in women and may consequently prevent GBS infections in newborns.

Effect of Bacteriocin-like Inhibitory Substances Produced by <i>Vaginal Lactobacilli</i> on Group B Streptococcus

“…This is in agreement with the findings of Ruiz et al (2012), who reported better performance of combined BLIS from L. rhamnosus L60 and L. fermentum L23 on GBS. However, while their combination resulted in a significant increase in activity, there was no significant difference in the activity of the combined BLIS in this study.…”

“…Our finding is in agreement with the study of Strus et al (2002), who reported the inhibition of GBS by species of Lactobacillus. Our findings are also consistent with the findings of Ruiz et al (2012) where BLIS produced by L. fermentum and L. rhamnosus were found to inhibit the growth of GBS.…”

The impact of oral probiotics on vaginal Group B Streptococcal colonisation rates in pregnant women: A pilot randomised control study

“…Recently, two separate studies have emerged which have performed in vitro experiments specifically investigating the impact of different strains of Lactobacillus on GBS (Bodaszewska-Lubas et al, 2012;Ruiz et al, 2012). The study by Ruiz et al (2012) found that the Lactobacillus strains rhamnosus L60 and fermentum/reuteri L23 have probiotic potential for the control of vaginal GBS colonisation.…”

“…The study by Ruiz et al (2012) found that the Lactobacillus strains rhamnosus L60 and fermentum/reuteri L23 have probiotic potential for the control of vaginal GBS colonisation. The strains used by Ruiz et al (2012) and the strains used in the present study are similar to the species level. The strains used in the present study are currently manufactured and readily available within the Australian market.…”

Lemon Juice Synergistically Preserved with Lactobacilli Ameliorates Inflammation in Shigellosis Mice

“…2 Lactobacilli produce a wide range of inhibitory compounds such as organic acids (lactic acid), hydrogen peroxide, diacetyl, bacteriocins and compete with other microorganisms by nutrient depletion. 3 Lactobacilli are also associated with traditional fermented products and thus have the Generally Recognized as Safe (GRAS) status granted by the US Food and Drug Administration (USFDA). 4 In addition, the beneficial effects of LAB from a healthy image associated with probiotic properties are suggested to be due to a number of factors including regulation of intestinal microbial homeostasis, maintenance of the gastrointestinal barrier function that prevents pathogens from adhering, interference with the ability of pathogens to colonize, changes in total enzyme activity in the colon contents, changes in the availability of nutrients and finally modulation of local and systemic immune responses.…”