Rise and fall of cholera-causing bacteria lineage

• Researchers identify the decline of antimicrobial resistance in O139 as a key determining factor in its downfall.

Cholera disease

• It is a life-threatening infectious disease and a public health hazard.
• Caused by comma-shaped bacterium known as Vibrio cholerae.
• More than two hundred serogroups of this bacterium are known, of which only O1 and O139 are known to cause such infection that leads to epidemics and pandemics.
• Other causes mild cholera-like diarrhoea and food-associated outbreaks.
• O1 was responsible for seven pandemic waves, only to be temporarily displaced by O139.
• This emerged late and came up around 1992.
  • It was first spotted in Chennai (then Madras).

Genomic changes

• Researchers have studied genome of O139 and traced reasons for its dying down after taking over from O1.
• First related to type of cholera toxin it produced
• Second is related to loss of anti-microbial resistance.

Surveillance necessary

• The study points to AMR as a factor that can decide success of certain populations of bacteria that can produce large outbreaks of disease.
• Continuous surveillance is necessary to monitor if any of the serotypes are gaining antibiotic resistance over time.
• Vaccines and treatments need to be regularly re-evaluated for efficiency to any newly evolving variants.