Research Highlights

How cholera bacteria defy antibiotics

doi:10.1038/nindia.2019.40 Published online 27 March 2019

Researchers have gained new insights into how different strains of the bacterium that causes cholera have developed resistance to multiple antibiotics1.

Besides shedding light on the evolution of drug-resistant bacteria, this study could provide better clinical guidance for managing such pathogens.  

Scientists from the Translational Health Science and Technology Institute and the Regional Centre for Biotechnology in Faridabad, the CSIR-Indian Institute of Chemical Biology in Kolkata and the Rajiv Gandhi Centre for Biotechnology in Thiruvananthapuram, all in India, analysed the antibiotic susceptibility of 443 strains of bacteria (Vibrio cholerae).

These were isolated from the stool samples of cholera patients in Kolkata and Delhi between 2008 and 2015.

The researchers, led by Bhabatosh Das, found that almost 99 per cent of the bacteria were resistant to two or more antibiotics, 17.2 per cent to 10 antibiotics and 7.5 per cent to 14 antibiotics. 

Resistance to the antibiotics imipenem and spectinomycin increased, but resistance to tetracycline decreased from 2008 to 2014. The resistance to rifampicin and ciprofloxacin increased in 2015, with a decrease in resistance to chloramphenicol and polymixin B.

The greatest concern is the resistance to beta-lactams, which are indispensable for managing infectious diseases and surgery-related infections.

Sequencing the whole genome of the drug-resistant bacteria, the researchers identified more than 40 antimicrobial resistance genes that the bacteria acquire from the environment. Antibiotic-resistance proteins, encoded by these genes, help the bacteria to defy the antibiotics.

The researchers say that the antibiotics eliminate the drug-sensitive bacteria, but stimulate the growth of the drug-resistant bacteria, allowing them to persist and spread resistance genes to other pathogenic bacteria.


References

1. Verma, J. et al. Genomic plasticity associated with antimicrobial resistance in Vibrio choleraProc. Natl. Acad. Sci. Unit. States. Am. (2019) doi: 10.1073/pnas.1900411116