Scientists in Buffalo have found a way to kill totally drug-resistant Escherichia Coli, a relief for doctors and other humans worldwide.
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Most strains of E. coli are benign beings that live peacefully in our intestines. When certain E. coli strains infect us elsewhere, they can cause infections, diarrhea, anemia, even kidney failure and death. Infection is generally caused by consuming food or drink contaminated by feces, which is why restaurants make employees wash their hands after using the john.
As long as infections could be treated with antibiotics, fine. But E. Coli, like gonorrhea, pneumonia, tuberculosis and a host of other germ-generated conditions has developed resistances, sometimes multiple ones. Recently doctors isolated strains resistant to even last-resort antibiotics, which meant – until now – that if you were infected with one of those, only your immune system and the deity could help you.
Resistance is commonly "donated" from one bacterium to others by "infecting" one another with plasmids, which are tiny extrachromosomal bits of DNA (i.e., plasmid DNA is not core to the bacterial DNA; they can do fine without it). Plasmids typically bear genes that are useful to the bacteria, and often bear resistance genes. Also, bacteria may be one-celled but many species have sex, after a fashion, which means they can exchange genetic material. Thus, bacteria can "infect" one another with resistance. (For an article on bacterial Dangerous Liaisons, click here).
The recently noticed E. coli superbugs contained two resistance genes, MCR-1 and NDM-5. Infection with this superbug could not be treated.
By the way, resistance genes aren't usually specific to a species of bacteria. MCR-1 for instance causes resistance in other bacteria too, including Klebsiella pneumonia, and has reached every populated continent on the planet.
"The threat of gram-negative bacteria, including E. coli carrying mcr-1, is worrisome," says Zackery Bulman, assistant professor at the University of Illinois, delicately. Especially as, being pretty much invincible, a superbug has the potential to spread really fast.
So how did the scientists kill super-E. coli? With a cocktail of antibiotics that attacks the bacteria in different ways.
After testing lots of combinations, they combined low dosages of polymyxins (a class of antibiotics that works great but is only used in dire need because of potential damage to the kidneys) with two known antibiotics, aztreonam and amikacin. The idea is to weaken the bug with the one drug – resistance isn’t absolute – while simultaneously attacking with more.
Polymyxins disrupt the cell walls and membranes of bacteria, and your kidneys, which is why they're last-resort. Bacteria can become resistant to them, though.
Now, the doctors found, if polymyxins are administered together with aztreonam, or amikacin – within a day, the E. coli almost disappeared from the patient. Almost. Within three days, they were back and roaring.
The bottom line is that if all three drugs are given together, they had a synergistic effect and the super-resistant bacteria died once and for all. May their memory be blessed.