Colistin: the last weapon
Antibiotic is the most loyal weapon against the disease caused by bacterial infection. Each antibiotic has their own way to fight off bacteria. They are made in such a way that certain bacteria can be defeated by taking its infection map in antibiotic's grip. But this simple phenomenon leaves us in a complete bewilderment when even an antibiotic struggle itself in the battlefield of immunity. The last hope, an antibiotic named 'Colistin' is such a kind, which has already lost the realm and at last surrendered to some bacterial species.
To know the sum-up chronicle of this war between colistin and bacteria, at first let us have some idea about the mechanism how colistin works. The bacterial cell membrane is the initial site of action for colistin. Colistin binds to lipopolysaccharide and phospholipids in the outer cell membrane of Gram-negative bacteria. It competitively displaces divalent ions (Ca2+ and Mg2+) from the phosphate groups of membrane lipids, which leads to disruption of the outer cell membrane, leakage of intracellular contents and bacterial death.
Some multi-drug resistant bacteria namely Klebsiealla pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa etc. have already shown resistance to colistin. Colistin was first discovered in 1970 though doctors never liked to recommend this antibiotic for its adverse side effect on health. In that case, another strong antibiotic named carbapenem was used by doctors to treat such bacterial infection that was impervious to other antibiotics. But the immunity war between antibiotic and germs turn to an unprecedented event; Irony favours to some certain tiny inferior bugs and at last they expose themselves as superior.
Now, the most important question is what earth inhabitants are doing to stop the war or are they trying to extract a sustainable solution from this burning issue? In 2015, colistin resistant gene named MCR-1 was found both in humans and animals. They isolated the gene from the bacteria named Klebsiella pneumoniae and E. coli. Their research towards this last shot of antibiotic was very convincing. Later in 2016, the same resistant gene was found in E. coli in a urinary tract infection (UTI) patient. The world has now reached a high concern level about this and they believe victory is very near. Such a positive step is applying a synergic method of using antibiotics on the superbug. Recently, scientists in Canada have used colistin in combination with other antibiotics to kill multi-drug resistant bacteria. This method has been proved to be very efficient on the super-germs as in the combination with other antibiotic, the toxic colistin is even fully functional in a very low concentration. Therefore, the chance of having an adverse effect is also low.
Three years have already been passed after the last resort antibiotic became a burning issue. Bangladesh is still lagging behind in this issue. Recently, a few enthusiastic groups are showing interest in this research. Though they are just at the beginner level of this antibiotic resistance research, they possess a very positive hope to know more and find a way to end this antibiotic apocalypse.
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The writer is a Research Fellow at the Institute for developing Science and Health initiatives (ideSHi).
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