Persistence of V. cholerae O139 Biofilm Against Physical, Chemical and Antibiotic Lethal Challenges

Since its emergence, cholera caused by the bacterium Vibrio cholerae remains as a significant threat to human health. The continued persistence of this pathogen against many unfavourable conditions made challenging to eradicate cholera, especially in the developing countries. In the hostile conditions, the bacterium is known to form a self-enclosed polymeric structure called ‘biofilm’ which serves as a major factor responsible for its persistence and transmission. Hence, the authors aimed to understand the effectiveness of relevant physical, chemical and antibiotic treatments against the biofilm of this bacterium. For the study, the biofilm of V. cholerae O139 wild type and its isogenic Tn5-mutants that differ in their biofilm phenotype (biofilm proficient and biofilm deficient) were exposed to different levels of pH, salinity, temperature, UV radiation, H 2 O 2 , chlorination, and antibiotics. It was observed that biofilm culture of both wild type and the biofilm-proficient mutant exhibited detectable survival rate up to pH 2.0, salinity 3.5 M, temperature 50 °C, H 2 O 2 80 mM, NaOCl 12.5 mg/L and at several folds increased antibiotic concentration (Ciprofloxacin 2 mg/L, and Doxycycline 256 mg/L) as compared to the biofilm defective mutant and the planktonic cultures of respective strains. As the biofilm of the cholera pathogen or the cholera biofilm resists several lethal challenges, it is essential to target the biofilm and its residents for the complete destruction of the infection source and thereby to prevent transmission of cholera.