Interference Between <i>Lactobacilli</i> And Group A <i>Streptococcus pyogenes</i>: An Expansion To The Concept Of Probiotics

Abstract

The use of probiotic bacteria, such as lactobacilli was found to be effective therapeutic alternative in some intestinal and urogenital infections. However, little is known about their health benefits in respiratory and skin infections. Accordingly, this work aimed to investigate the ability of 32 Lactobacillus isolates to inhibit some pathogenic activities of group A Streptococcus pyogenes (GAS). Four of these isolates (LR6, LR13, L. oris2 and L. rhamnosus1) significantly blocked the adherence of GAS to both Detroit and FaDu cells using competition, displacement and exclusion test techniques. Moreover, these isolates dramatically inhibited the in vitro growth of GAS. They also induced the IL-6 production by FaDu cells to levels comparable to that brought about by GAS infection and counteracted the IL-8 decreasing property of GAS which was reported as an important immune evasion mechanism by the pathogen. With exception of L. rhamnosus1, the isolates markedly protected the mammalian cells from the cytotoxic effect of GAS. Collectively, these data indicate that L. reuteri6, L. reuteri13, L. oris2 are promising candidates as probiotics with therapeutic potential against GAS infections, since they have antagonistic activity against the adherence of the pathogen, its in vitro growth, its cytotoxic potential and some of its immune evasion mechanisms. These findings may also expand the concept of probiotics to new types of infections as skin and respiratory tract infections.New Egyptian Journal of Microbiology Vol. 17 (2) 2007: pp. 262-284