Effect of Lactobacillus acidophilus on Escherichia coli causing Urinary tract infections in Vitro and in Vivo


One hundred and sixty five mid stream urine specimens were collected from outpatients presented with urinary tract infections (UTI). The results showed the dominance of Escherichia coli over other causative agents. Antibiotic sensitivity test was carried out to E. coli isolates. Thence, the isolate that developed the highest multidrug resistance was chosen for further studies. Moreover, five Lactobacillus isolates comprising L. acidophilus L1 and L. acidophilus L2 were isolated from yogurt and vinegar, respectively, L. plantarum L3 and L. plantarum L5 from saliva and raw milk, respectively, while L. fermentum L4 was isolated from vagina. Cup assay method was employed to investigate the inhibitory (antagonistic) activity of lactobacilli isolates against E. coli A99 on MRS agar. Results showed that L. acidophilus L1 developed the highest activity. The cell free supernatant of lactobacilli developed the same activity. L. acidophilus L1 supernatant showed the highest inhibition activity. The present study also revealed this activity in vivo by injecting a group of mice with L. acidophilus L1 suspension or its infiltrate 30 min after injecting the E. coli A99 intraurethrally and the histopathological sections revealed the disappearance of inflammation signs caused by E. coli A99 when it was injected alone.