In Vitro assessment of anti-Campylobacter activity of lactobacillus strains isolated from canine rectal swabs

Abstract

Background: Campylobacteriosis is currently the most frequently reported zoonosis. Dogs, especially puppies or those with diarrhea, are considered a possible source of human infection. Probiotic bacteria, such as Lactobacillus species, seem to be a valuable tool in controlling of intestinal pathogenic microorganisms in dogs. The main purpose of this study was to assess the anti-Campylobacter activity and some probiotic properties, like ability to produce H₂O_2, bile salt and low pH tolerance of Lactobacillus strains isolated from gastrointestinal tract of healthy dogs.

Results: A total of 39 rectal swabs derived from healthy dogs and 19 from dogs with diarrhea were examined to detect Lactobacillus and Campylobacter bacteria respectively. In total, 30 strains of Lactobacillus genus and four strains of Campylobacter genus were isolated and identified. Of the 30 strains of Lactobacillus, 22 showed an inhibitory effect towards Campylobacter. Four strains with the strongest antagonism towards Campylobacter bacteria (L. salivarius 25 K/L/1, L. rhamnosus 42 K/L/2, L. sakei 50 K/L/1 and L. agilis 55 K/L/1) were selected to assess their potential probiotic traits. Three out of four analyzed strains produced extracellular H₂O_2. All displayed very good or moderate survival at pH 3.0 and 2.0 and showed high tolerance to 0.5% and 1% bile salts.

Conclusions: Among selected Lactobacillus strains, all may have a potential probiotic application in reducing Campylobacter spp. in dogs and thus prevent transmission of infection to humans, although the best candidate for probiotic seems to be L. sakei 50 K/L/1. Further in vitro and in vivo studies are needed.

Keywords: Antibacterial activity; Campylobacter; Dog; Lactobacillus; Probiotics.

Fig. 1

Antagonistic activity of some Lactobacillus isolates against reference strains of Campylobacter in the agar slab method

Fig. 2

Relation of Campylobacter number [log CFU/ml] with the antibacterial activity of Lactobacillus strains. Error bars represent standard errors. Asterisks indicate the statistical differences: * P < 0.05