Anti-microbial susceptibility pattern of spores used in Bacillus clausii suspension: an in vitro study

Abstract

Background: Bacillus species have been used as probiotics as they have high stability to gastrointestinal conditions and impart health benefit on the host. Primarily used in their spore form the diversity of Bacillus species being used and their applications are remarkable. Here, we present the results of the antimicrobial susceptibility testing of the B. clausii spore suspension (Benegut®).Methods: Bacillus clausii spore suspension (Benegut®), used in oral bacteriotherapy was tested for the susceptibility to therapeutically useful antibiotics. Twelve commercially prepared, paper antibiotic discs of different drugs having fixed concentrations were used. The antimicrobial susceptibility test was performed by the disc diffusion technique, using soybean casein digestive agar (SCDA) as media and the results were categorized as susceptible, intermediate, or resistant; using the criteria published by the Clinical and Laboratory Standards Institute.Results: B. clausii was found to be resistant to broad-spectrum antibiotic chloramphenicol, antimycobacterial rifampicin, beta-lactamase inhibitor amoxiclav, first-generation antibiotic cefaloridine, penicillin ampicillin, and tetracycline. B. clausii was resistant to both the aminoglycoside antibiotics (streptomycin and kanamycin) studied. Off first-generation fluoroquinolones studied, B. clausii was resistant to ciprofloxacin but partially sensitive to norfloxacin, ofloxacin and to macrolide azithromycin. Conclusions: Antimicrobial resistance is an important feature of probiotics. The results of our study indicate that the antimicrobial and immunomodulatory activity B. clausii spore suspension (Benegut®) can profess beneficial effects and can be a useful source of improving the intestinal imbalance of microbial flora and is safe for human consumption.