The Effect of Antibiotics on the Growth of Chromobacterium violaceum

Chromobacterium violaceum (CV) is an opportunistic pathogen found in soil and water from tropical and subtropical regions of the world. It is a Gram negative facultative anaerobic proteobacterium. This bacterium is able to produce a large variety of products of biotechnological and pharmacological use. Although this organism is considered to be non-pathogenic, it causes infection when people are exposed to contaminated water and the pathogens enter the bloodstream via an open wound. Thus, it is of interest to determine which antibiotics are effective for control of this potential pathogen. The goal of this research was to test the susceptibility and effect of selected antibiotics on CV growth, at different concentrations in solid and liquid media. In this study, strains CV14N1, CV14N23, and CV12472 were exposed to several antibiotics, tetracycline (TET), gentamicin (G), chloramphenicol (C), erythromycin (E), penicillin (P), streptomycin (S), and vancomycin (VA). It was found that the antibiotics impaired bacterial growth levels, at the at sub-MIC concentrations initially. However, it was noted that these strains developed a level of tolerance to the antibiotics after 48 hours of exposure. Also, it was found that the three CV strains were resistance to penicillin (P), streptomycin (S), and vancomycin (VA), at the tested concentrations. Thus, it was concluded that these CV strains were sensitive to some antibiotics, initially developing resistance with long term exposure. Therefore, antibiotic treatment should include the use of multiple antibiotics to treat infections. It was also found that exposing the strains to antibiotics in the presence of tannins increased the efficiency of the antibiotics to inhibit Chromobacterium violaceum growth. Further studies will be to understand the mechanism by which Tannic Acid enhance the effect of the antibiotics on CV growth. Also of interest is understanding the mechanism by which vancomycin changed the morphology of the organism