| Introduction:In the past decade there has been an increased interest in the study of the intestinal microbial balance. Human intestine has vast variety of microorganisms and their balance is dependent on several factors such as gastric acidity, gut motility, bile salts etc. Microbial disturbances may cause a variety of diseases or abnormal physiological states. Infection and exposure to antibiotics change intestinal microbial balance and create the opportunity for the growth of pathogens and allows naturally opportunists to over grow and translocate to extra intestinal niches. Staphylococcus aureus and Pseudomonas aeruginosa are well known opportunists and nosocomial pathogens. They appear to have the opportunity and the ability to promote intestinal and respiratory infections. They are largely the cause of morbidity and mortality in both hospital and community settings. These pathogens remain the important cause of pulmonary infections in patients with Cystic fibrosis with a worldwide prevalence. Although antibiotics are still an effective means of treating bacterial infections, the alarming rise of multi drug resistant bacteria has urged to seek for the new therapeutic approaches. Thus, there is a need for the development of potent antimicrobial for the effective treatment of infections. Currently Lactobacillus and Bifidobacterium species are attracting great interest as health supplements because of increased awareness of the beneficial roles in health and nutrition. Lactic acid bacteria are generally recognized as safe organisms and can be used as probiotics. They have the potential to inhibit pathogen colonization and modulate immune response. They play role in keeping the gut microbial ecosystem stable by restoring normal microflora. There is evidence that maintaining balanced intestinal microbial ecosystem can antagonize the access of respiratory and enteric pathogens.Objectives:To investigate the capability of orally administered L. acidophilus to ameliorate pulmonary infections caused by S. aureus and P. aeruginosa.To demonstrate the role of Ingested Lactic acid bacteria in the restoration of intestinal microbial balance.To investigate the effects of Lactic acid bacteria on enterocytes infection of S. aureus and P. aeruginosa.Materials and Method:For pulmonary infection study, animals were exposed to aerosol of pathogenic suspension. L. acidophilus treatment was administered orally for 7 consecutive days. Evaluation of tissue bacteriology, histology and serum cytokines were done. In parallel, human alveolar A549 cells were utilized to determine possible role of probiotic on pulmonary infections.For intestinal microbial ecosystem, fecal samples were collected from animals, DNA was extracted followed by PCR amplification and denaturing gradient gel electrophoresis (DGGE). Culturable fecal bacterial count using microbiological media and PCR with group specific primers were also utilized to analyze the effects of antibiotic and probiotic on microbiota.For enteric infection study, Lactobacillus whole cells and their neutralized cell free supernatant (CFS) were used to analyze the effect on LoVo human carcinoma enterocytes infection followed by Fluorescence microscopy.Effect of Lactobacilli on viability of S. aureus and P. aeruginosa was detected by using BacLight bacterial viability staining followed by flow cytometry.Results:Oral administration of L. acidophilus significantly (P< 0.05) alleviate lung bacterial count and severity of infection as depicted by histopathology score. Results obtained from cytokinomics revealed that pro-inflammatory cytokines induced due to lung infection were suppressed in oral probiotic treatment groups. In addition, treatment with L. acidophilus induced anti inflammatory, IL-10 cytokine level.It was determined that gut microbial balance was destroyed due to lung infection and the total amount of 16S rRNA gene and fecal aerobic bacterial count was reduced following antibiotic administration along with over growth of Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, PCR using group specific primers revealed that Enterobacteriaceae were nearly same in probiotic group and decreased in antibiotic group while Bifidobacterium was significantly increased in the probiotic group and decreased in antibiotic group (P< 0.05) as compared with that in the control group.In this study, Lactobacillus whole cell and its CFS significantly (P< 0.05) eradicated the occurrence of enterocytes infection by pathogens when they were applied simultaneously. The mechanisms underlying this result have involved interference extracellular polymeric substance and cell surface hydrophobicity causing pathogen devoid of colony formation.Conclusion:Minimal disruption in intestinal microbiota caused due to lung infection or antibiotic exposure can result in prolonged injurious effects on the ability of the host to resist infections. Present work reveals that the use of Lactic acid bacteria particularly L. acidophilus help to retrieve intestinal microbial balance. Lactobacillus acidophilus as probiotics could be the best candidates in order to treat aero-gut infections because of their additional ability of bile acid tolerance.Current work suggests that L. acidophilus is able to attenuate gut and lung cytotoxic effect induced by S. aureus and P. aeruginosa probably by interfering extracellular polymeric substance and cell surface hydrophobicity causing pathogens devoid of colonization and indirectly by modulation of host immune response. |
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