Antibiotic Resistance, Toxicity and Antibacterial Soaps

Speaker: Calvin A. Carlyle

Abstract: The objective for this research was to isolate naturally occurring bacterial isolates who are either antibiotic resistant or highly toxic and evaluate if they are susceptible to antibacterial soaps and detergents. Naturally occurring bacteria were isolated from seven sites around Oregon State University campus and cultured at 37oC. Seven bacterial isolates (named C1 through C7) were characterized according to Gram stain, morphology, growth characteristics, antibiotic resistance and toxicity (toxin producing). For the three Pseudomonas sp. isolated they were resistant to all antibiotics tested. For the single Clostridium sp. isolated, it was sensitive to all antibiotics tested. For the three Bacillus sp. isolated, there were varying results with respect to antibiotic resistance. During the course of these studies it was discovered that increasing antibiotic concentrations did not impact the results of the antibiotic resistance assay. Conclusions from the toxicity test revealed that bacterial isolates C1 (a Bacillus sp.), C5 (a Clostridium sp.) and C7 (a Bacillus sp.) caused the pigmented biosensor cells to react (aggregated) suggesting the presence of a bacterial toxin. Bacterial isolates C2 (a Bacillus sp.), and C3, C4 and C6 (all Pseudomonas sp.) did not affect the pigmented biosensor cells suggesting no presence of bacterial toxin. Interestingly, the Clostridium isolate, who was sensitive to all antibiotics tested, elicited the most toxic response in the pigmented biosensor cell toxicity assay. The testing of antibacterial soaps and detergents is still in progress.