The antimicrobial potential of Lactobacillus acidophilus on pathogenic bacteria causing diarrhea

Rasha H Bassyouni,Mohammed Saad Zaghloul Ahmed,Mohammed Wasim Ahmed Nassar,Zeinab Abdelkhalek Ibrahim

doi:10.3823/764

Abstract

Object: Lactobacillus acidophilus is a nonpathogenic member of gastrointestinal tract and it is widely used in fermented dairy products.Â This study aimed to assess the antimicrobial potential of two strainsÂ of L. acidophilus on some pathogenic bacteria frequently causing diarrhea or gastroenteritis.Methods: The antibacterial activity cell free supernatant (CFS) of twoÂ control standard strains of L. acidophilus (L. acidophilus-la5 and L.Â acidophilus against fie control standard strains of bacteria causingÂ diarrhea; Enterotoxogenic Escherichia coli (ETEC), EnterohaemorrhagicÂ E. coli OÂ 157:H7(EHEC) Salmonella typhimurium Shigella flxeneri andÂ Staphylococcus aureus were determined using agar well diffusionÂ method. The sensitivity of the pathogenic bacteria to the CFS of eachÂ L. acidophilus in relation to time was determined by standard plateÂ count .The antibiotic susceptibility tests of 20 antibiotics against tested organisms with and without CFS were assessed by disc diffusionÂ method. The minimum inhibitory concentration (MIC) of ciproflxacinÂ with and without CFS was determined by tube dilution method.Results: Both Lactobacilli strains decrease the colony count of testedÂ strains by more than 90% after 60 min contact time. Both LactobacilliÂ strains signifiantly improve the antibacterial effect of tested antibiotics against ETEC, S. typhimurium and S. aureus, and S. flxeneri (P<Â 0.05). The MIC of ciproflxacin alone against all tested strains wasÂ 15.625 I¼g/ml, while when combined with both Lactobacilli CFSs, theÂ MIC decreased signifiantly to 0.488 I¼g/ml for ETEC, S. typhimurium,Â and S. flxeneri and to 0.977 I¼g/ml for EHEC and S. aureus (P= 0.000).Conclusion: living L. acidophilus strains could be used in preventionÂ and treatment of diarrhea caused by certain bacterial pathogens, either in fermented milk/ yoghurt or as mediations.

Highlights

Infective bacterial diarrhea is a global health problem especially in young children in developing countries with rotavirus is the most common identified pathogen [1]
The aim of this study was to investigate the antimicrobial potential of two L. acidophilus strain on pathogenic bacteria frequently causing diarrhea or gastroenteritis with and without antibiotics
We have studied the effect of Lactobacillus acidophilus on diarrhea causing bacteria; E. coli, S. typhimurium, S. flexeneri and S. aureus

Summary

Introduction

Infective bacterial diarrhea is a global health problem especially in young children in developing countries with rotavirus is the most common identified pathogen [1]. When diarrheal patients were given probiotics prior to or during hospitalization, a reduction in the frequency of diarrheal symptoms has been reported in both adults and children [1, 3]. Probiotics are preparations of living bacteria and yeasts that possess a beneficial health effect when administrated in adequate amounts [1, 4].They have been extensively studied for their beneficial effects in preventing and treating many conditions, including the treatment of lactose intolerance, traveller’s diarrhea and the prevention and treatment of hospital acquired diarrhea[5, 6]. It has been reported that most probiotics are well tolerated with rare adverse effect and can be safely used in patients with underlying chronic diseases or in those on immunosuppressive therapy [1]

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