Drug from waste

Chitosan can provide protection against typhoid

Last Updated: Saturday 04 July 2015

researchers from the Government College of Pharmacy, Tamil Nadu, have found that chitosan -- a natural polymer found in the waste of the processed seafood industry -- can provide protection against typhoid. Chitosan is derived from chitin, present in the exoskeleton of crustaceans such as crabs, lobsters and shrimps.

To study the anti-microbial potential of the polymer, the researchers placed paper cups containing chitosan dissolved in citric acid in plates of nutrient containing colonies of different typhoid-causing bacterial strains. After the plates were incubated for 24 hours, they were analysed for microbial growth inhibition. "We found that chitosan has an exceptionally good anti-bacterial activity," wrote A V Yadav and S B Bhise in the November 10 issue of the journal Current Science.

As a next step, the researchers compared the anti-microbial activity of chitosan with that of standard antibiotics. Its efficacy against several strains of the typhoid-causing Salmonella enterica , which are resistant to commonly-used antibiotics such as chloramphenicol and ciprofloxacin, was found to be relatively high. The researchers hope the molecule will be used by the pharmaceutical industry to overcome the problem of resistance faced by many drugs.

The reliable cure
High levels of chitosan can even kill those typhoid-causing microbes that cannot be otherwise controlled by commonly-used drugs
Chitosan* (in microgrammes) 

Zone of inhibition** (in millimetres)

Bacteria Zone of inhibition (in millimeters)




Staphylococcus aureus    40


Bacillus subtilis     20


Pseudomonas aeruginosa     16


Salmonella enterica    32


Escherichia coli  18
50  15 S enterica variant Paratyphi-A    32
10     Nil S enterica variant Paratyphi-B    25
*Activity against Salmonella enterica; **Zone of inhibition is where a chemical inhibits the growth of bacterium in a test medium. If the diameter of the zone is more than 15 millimetres, the chemical is said to have antimicrobial property
Source: Current Science, November 10, 2004

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