Antagonistic activity exerted in vitro and in vivo by Lactobacillus casei (strain GG) against Salmonella typhimurium C5 infection

Abstract

The aim of this study was to compare the antagonistic properties of Lactobacillus casei GG exerted in vitro against Salmonella typhimurium C5 in a cellular model, cultured enterocyte-like Caco-2 cells, to those exerted in vivo in an animal model, C3H/He/Oujco mice. Our results show that a 1-h contact between the invading strain C5 and either the culture or the supernatant of L. casei GG impeded the invasion by the Salmonella strain in Caco-2 cells, without modifying the viability of the strain. After neutralization at pH 7, no inhibition of the invasion by C5 was observed. The antagonistic activity of L. casei GG was examined in C3H/He/Oujco mice orally infected with C5 as follows: (i) L. casei GG was given daily to conventional animals as a probiotic, and (ii) it was given once to germ-free animals in order to study the effect of the population of L. casei GG established in the different segments of the gut. In vivo experiments show that after a single challenge with C5, this strain survives and persists at a higher level in the feces of the untreated conventional mice than in those of the treated group. In L. casei GG germ-free mice, establishment of L. casei GG in the gut significantly delayed the occurrence of 100% mortality of the animals (15 days after C5 challenge versus 9 days in germ-free mice [P < 0.01]). Cecal colonization level and translocation rate of C5 to the mesenteric lymph nodes, spleen, and liver were significantly reduced during the first 2 days post-C5 challenge, although the L. casei GG population level in the gut dramatically decreased in these animals. Recently, Klaenhammer (21) proposed that Lactobacillus strains with well-defined properties should be selected and characterized for specific use. Among Lactobacillus strains used in fermented milks, Lactobacillus casei GG has been shown to promote clinical recovery from acute rotavirus diarrhea in infants (17-20, 24) and from either antibiotic-associated or traveller's diarrhea in adults (27, 36). It has been previously reported that L. casei GG adheres to enterocyte-like cells in culture (11). It exerts an antagonistic effect against several bacteria and produces an unknown antimicrobial substance against Escherichia coli (37). But the mechanism of action of L. casei GG in vivo remains unknown. We have recently reported that selected, adhering human L. acidophilus strains inhibit both cell association and cell entry of a variety of enterovirulent bacteria within human cultured enterocyte-like Caco-2 cells (5-8). In the present work, we have compared the antagonistic effect observed in vitro in a cellular model (Caco-2 cells) to that observed in an in vivo animal model (C3H/He/ Oujco mice). First, we studied whether L. casei GG can inhibit the invasion of cultured enterocyte-like Caco-2 cells by Salmonella typhimurium C5 (28). Second, the antagonistic activity of L. casei GG was examined in C3H/He/Oujco mice orally infected with S. typhimurium C5. Two experimental designs were used: (i) L. casei GG given daily to conventional animals as a ...

Individual and co-operative roles of lactic acid and hydrogen peroxide in the killing activity of enteric strain Lactobacillus johnsonii NCC933 and vaginal strain Lactobacillus gasseri KS120.1 against enteric, uropathogenic and vaginosis-associated pathog

“…Consistent with this hypothesis, Niku-Paavola et al (1999) have proposed that compounds secreted by Lactobacillus plantarum act synergistically with lactic acid, and Makras et al (2006) observed that L. johnsonii NCC533 CFCS was effective against serovar Typhimurium by unknown inhibitory substance(s) that are only active in the presence of lactic acid. These nonlactic acid, heat-resistant anti-Salmonella molecule(s) present in the CFCSs of probiotic Lactobacillus strains have not yet been identified (McGroarty & Reid, 1988;Bernet-Camard et al, 1997;Coconnier et al, 1997;Hudault et al, 1997;Ocana et al, 1999;Aroutcheva et al, 2001b;van de Guchte et al, 2001;Sgouras et al, 2004Sgouras et al, , 2005Fayol-Messaoudi et al, 2005Atassi et al, 2006a). It has already been suggested that pyroglutamic acid may be responsible for the antimicrobial activity of L. rhamnosus GG and L. casei strains LC-10 and LB1931 (Silva et al, 1987;Huttunen et al, 1995;Yang et al, 1997), but it has been found to be intrinsically present in MRS medium and it does not increase during bacterial growth (De Keersmaecker et al, 2006).…”

In vitro fermentation of carbohydrates by porcine faecal inocula and their influence on Salmonella Typhimurium growth in batch culture systems

“…In order to observe an inhibitory effect, the addition of higher amounts of lactic acid bacteria than that naturally present in the GIT may be needed. Thus, the addition of probiotic species in the feed has been demonstrated to be effective against Salmonella Typhimurium infection in both murine and porcine models (Hudault et al, 1997;Silva et al, 1999;Casey et al, 2007;Chiu et al, 2008).…”

Lactobacillusstrains isolated from the vaginal microbiota of healthy women inhibitPrevotella biviaandGardnerella vaginalisin coculture and cell culture

“…It is interesting to note that the killing activity of L. gasseri strain KS120.1 against G. vaginalis and P. bivia is in the range of killing activity stipulated for the lethal or bactericidal activity of an antimicrobial agent. Indeed, bactericidal activity is defined as the killing activity needed to kill most of ( 4 99.9%) a test microorganism after being incubated with it for a fixed length of time under Coconnier et al, 1997;Hudault et al, 1997;Lievin-Le Moal et al, 2002;Fayol-Messaoudi et al, 2005;Atassi et al, 2006). Interestingly, we reported that when G. vaginalis-or P. biviapreinfected HeLa cells were subjected to L. gasseri KS120.1 culture or L. gasseri KS120.1 CFCS treatments, a significant decrease in the viable, adhering G. vaginalis and P. bivia is observed compared with untreated, preinfected cells.…”