Clinical Microbiology: Open Access

Interruption of quorum- sensing mechanism by guava-leaf-extract prevents pathogenicity of Chromobacterium violaceum: Validation by whole-genome-transcriptomic data

3^rd International Conference on Clinical Microbiology & Microbial Genomics

September 24-26, 2014 Valencia Convention Centre, Spain

Ranadhir Chakraborty, Runughosh, Bipransh Kumar Tiwary and Anoop Kumar

Accepted Abstracts: Clin Microbial

Abstract:

Chromobacterium violaceum, an opportunistic pathogen, is a free-living, gram-negative, facultative anaerobic β- proteobacterium commonly found in water and soil in the tropical and subtropical regions. In humans, C. violaceum infection is rare, but this may be attributed to under-reporting of such cases in areas where the risks of exposure are high and diagnostic facilities are scarce. This rare infection is associated with a high mortality rate, between 60% and 80%, if not diagnosed at an early stage or treated correctly. A likely explanation for the high mortality rate could be theresistance of C. violaceum to a wide range of antibiotics and to other mechanisms that pump out the cytotoxic drugs. Thus, appropriate therapy is absolutely essential to control this neglected, potentially fatal infection. The strategy of controlling pathogens by interrupting its QS phenomenon was theprime focus of research in the recent years. The C. violaceum quorum-sensing system consists of the LuxI/LuxR homologues CviI/CviR, which controls virulence and the production of a variety of phenotypic characteristics that includes the production of the purple pigment, violacein, cyanide, chitinase and the antibiotic phenazine. Crude extracts of many plant parts were shown to possess anti-QS activity using C. violaceum as a model bacterium. Crude plant extracts are often found to be more effective than isolated constituents at an equivalent dose perhaps owing to positive interactions between components of whole plant extracts. Hence, it is lately realized that crude extracts may possibly be the right strategy to treat multi-drug resistant pathogens as compared to the purified compound isolated from the same extract. Psidium guajava L. (Guava), widely distributed throughout India, belongs to the family Myrtaceae and is a well known traditional medicinal plant widely used in folk medicine. However, no molecular mechanism of antimicrobial property of guava-leaf extract was explored. In this paper, we will describe the differential gene expression of C. violaceum in presence of guave-leaf-extract (GLE) by whole transcriptome analysis on Ion-Torrent. The down-regulation of the plausibly quorum regulated wide array of genes, including those encoding virulence factors, affecting pathogenicity will be discussed. Consistent with the gene expression pattern, the data where GLE treated C. violaceum cells failed to cause lysis of human hepatoma cell line, Hep G2, indicating a positive relationship between the QS-regulated genes and pathogenicity will be presented.

Biography :

Ranadhir Chakraborty worked for his PhD from the Department of Microbiology, Bose Institute, Kolkata, India, under Calcutta University. He is the Head and Course Coordinator for DBT, Govt. of India sponsored MSc course in Biotechnology, University of North Bengal, West-Bengal, India. His overall research expertise is in the field of Molecular Microbiology and Bio-molecular Technology. He has published more than 50 papers in reputed journal and has been serving as members of several academic bodies of several Indian Universities.