In-vitro antibacterial activity of commercially available probiotics on food-borne pathogens along with their synergistic effects with synthetic drugs.

Background: Probiotics are put forward as food to ensure the maintenance of the equilibrium of the intestinal flora. Prolonged usage of probiotics in food ingredients for human as well as in animal feed has not exposed any side effects yet. Present study attempted to justify the effects of some commercially available probiotics (Good-gut, Lubenna, Probio and Protein restro) and commonly used antibiotics (Streptomycin, Gentamycin, Ampicillin, Methicillin, Azithromycin, Erythromycin, Ceftrizone, Imepenem, Ciprofloxacin and Tetracycline) on the bacteria which were previously isolated from food samples. Methods: The anti-bacterial potential of the probiotics was aimed to be checked through the agar well diffusion method and the antibiogram of the synthetic drugs was determined by disc-diffusion method (Kirby Bauer technique). The minimum inhibitory concentration (MIC) of the probiotics were examined through broth micro dilution assay. Results: Almost all the probiotic samples exhibited antibacterial activity against the tested bacteria within the range of 10 mm-30 mm except Bacillus spp. and Salmonella spp. The lowest MIC values 3 mg/ml was determined with Luvena for Pseudomonas spp. and Shigella spp. while the maximum MIC 20 mg/ml was recorded for Good gut and Probio against Salmonella spp. and E. coli. Meanwhile, majority of the tested pathogens were detected to be resistant against more than one antibiotic as MDR strains except gentamycin, streptomycin and azithromycin. During the combination method, the zone diameter increased remarkably with a clear indication of synergistic effects compared to their individual activity. Conclusion: This study substantiated that the deployment of a combination of two antibacterial medications in order to combat the multi-drug resistant bacteria would rather be efficacious than the application of either antimicrobial agent alone.

Survival of Bacillus spp. SUBB01 at high temperatures and a preliminary assessment of its ability to protect heat-stressed Escherichia coli cells.

BACKGROUND: The bacterial stressed state upon temperature raise has widely been observed especially in Escherichia coli cells. The current study extended such physiological investigation on Bacillus spp. SUBB01 under aeration at 100 rpm on different culture media along with the high temperature exposure at 48, 50, 52, 53 and 54 °C. Bacterial growth was determined through the enumeration of the viable and culturable cells; i.e., cells capable of producing the colony forming units on Luria-Bertani and nutrient agar plates up to 24 h. Microscopic experiments were conducted to scrutinize the successive physiological changes. Suppression of bacterial growth due to the elevated heat was further confirmed by the observation of non-viability through spot tests. RESULTS: As expected, a quick drop in both cell turbidity and colony forming units (~10(4)) along with spores were observed after 12-24 h of incubation period, when cells were grown at 54 °C in both Luria-Bertani and nutrient broth and agar. The critical temperature (the temperature above which it is no longer possible to survive) of Bacillus spp. SUBB01 was estimated to be 53 °C. Furthermore, a positive impact was observed on the inhibited E. coli SUBE01 growth at 45 and 47 °C, upon the supplementation of the extracellular fractions of Bacillus species into the growing culture. CONCLUSIONS: Overall the present analysis revealed the conversion of the culturable cells into the viable and nonculturable (VBNC) state as a result of heat shock response in Bacillus spp. SUBB01 and the cellular adaptation at extremely high temperature.

Microbiological profiling and the demonstration of in vitro anti-bacterial traits of the major oral herbal medicines used in Dhaka Metropolis.

Present study attempted to assess the level of microbiological contamination in oral herbal medicines, frequently used for medications, through conventional cultural and biochemical tests along with the antibiogram of the isolates. Moreover, the anti-bacterial potential of the herbal medicines was also aimed to be checked by the agar well diffusion method and minimum inhibitory concentration (MIC) assay. Out of 10 categories of liquid oral herbal medicine samples (n = 50) studied, all were found to be contaminated with bacteria (10(3)-10(5) cfu/mL), specifically with Staphylococcus spp. in 8 samples; while 2 samples harbored Klebsiella spp. Fungal presence was observed only in one sample. Study of antibiogram revealed Klebsiella spp. to be strongly resistant against penicillin G and erythromycin, whereas S. aureus possessed 80% sensitivity. The in vitro anti-bacterial activity was observed in 7 samples. Of them, one sample was found to exhibit the activity against almost all the test bacteria and another was found effective against 5 out of 8 test bacteria. Five samples showed the activity within a minor range while 3 samples were devoid of such trait. Samples 2 and 4 were found to stall the bacterial growth below 10 mg/mL of concentration in MIC test. Overall, the prevalence of specific pathogens was not so significant in the samples studied as well as only one drug-resistant isolate was identified. Besides, the anti-bacterial trait of 5 samples indicated that most of herbal medicines might be considered effective for medication.