Journal of Probiotics & Health
Open Access

Abstract

Effect of Lactobacillus plantarum Strains on Clinical Isolates of Clostridium difficile in vitro

Merle Ratsep, Paul Naaber, Siiri Kõljalg, Imbi Smidt, Elena Shkut and Epp Sepp

Probiotic bacteria are proposed for prevention of Clostridium difficile associated diarrhea. The aim of this in vitro study was to evaluate the influence of five Lactobacillus plantarum strains to the survival of C. difficile reference strains (M13042 and VPI 10463) and clinical isolates (n=12) using co-culturing and micro-titre plate assay. Changes in bacterial growth were assessed over the time period of 48 h. Quantitative analysis of C. difficile population revealed that there was a significant decrease of C. difficile in co-culture compared to the control (p=0.01). Susceptibility against L. plantarum was C. difficile strain specific, while L. plantarum was not affected by the presence of C. difficile. Reference strains were more sensitive to inhibition than most of the clinical strains (M13042 strain vs eight clinical strains, p=0.03; VPI vs six clinical strains, p=0.04). Fluoroquinolone resistant C. difficile strains were less inhibited by L. plantarum than sensitive strains (p<0.05). In the micro-titre plate assay experiment the inhibition of C. difficile was not related to any particular C. difficile strains however, inhibitory activity was affected by treatment of supernatants. Supernatants of tested lactobacilli inhibited the C. difficile growth from 72% to 82% if nonneutralized (p=0.001); 43% to 68% if neutralized (p=0.003) and 92% to 99% (p=0.001) if supernatant was neutralized and heated as compared to controls.