Samples (98 plaque and 72 saliva) from 93 patients with dental caries were
investigated for Lactobacillus species which comprised 65 (62.5%)) of 104 i
solates. Yeasts (20.1%), Streptococcus spp. (8.7%), Staphylococcus spp. (2.
9%) and a few unidentified species (5.8%), were also found. The Lactobacill
us isolates were L. brevis (24.6%) L, fermentum (18.5%) L. casei(16.9%), L.
delbrueckii (15.4%), L. plantarum (9.23%), L. acidophilus (7.69%), L. jens
enii (4.62%), L. salivarius (1.54%) and L. gasseri(1.54%). The most common
species was L. brevis (24.6%). The strains tested for beta-lactamase produc
tion showed 75.4% positive. All the Lactobacillus strains were tested for b
acteriocin production against Escherichia coil, Salmonella spp., Shigella d
ysenteriae, S. sonnei, Klebsiella spp. and Campylobacter sp. All the lactob
acilli except L. jensenii produced bacteriocin against at least one of the
indicator organisms. The involvement of Lactobacillus in dental caries was
established, although its role and mechanism is not well understood. The ab
ility of Lactobacillus spp. to protect their host against certain diseases
by inhibiting the growth of potential pathogens was evident.