Inhibitory Effect of Lactobacillus acidophilus and Klebsiella pneumoniae on Common Enteropathogens Isolated from Food and Clinical Materials

Bacteriocins of Lactobacillus acidophilus (lacticin) and Klebsiella pneumoniae (klebocin) have been found to inhibit the growth of various enteropathogens. This study deals with effect of 3 strains of L. acidophilus (LB-I, LB-R and LB-3) and one strain of Klebsiella pneumoniae (K-4) on 73 strains of enteropathogens of zoonotic significance. Culture supernatants of LB-I strain was the most effective to inhibit the growth of 35 strains out of the 73 tested, while, supernatant of LB-R, LB-3 and K-4 strains could inhibit growth of only 30, 19 and 31 strains, respectively. None of the Lactobacillus inhibited Proteus mirabilis, Morganella morganii and Plesiomonas shigelloides strains. However, K-4 supernatant had weak inhibitory effect on P. shigelloides. About 50% of the pathogens isolated from human patients were inhibited; inhibitory activity and spectrum of activity appeared to be strain dependent rather than having any association with pathogenicity potential. Two non-pathogenic reference strains of Escherichia coli K12 were equally inhibited by all the 3 Lactobacilli and 1 Klebsiella, but a pathogenic reference strain had resistance to all 4 bacteriocins. The study revealed that bacteriocin resistance is common in environmental as well as in clinical isolates of enteropathogens.