Antibiotics have been becoming less and less effective against bacteria for many years now. This leads to scientists trying to not only create new antibiotics but also alternative methods to combat these bacterial menaces. A question you might be asking though is, "How do these bacterial viruses combat our antibiotics in the first place?" Well, this article is just for you!
So, there are four main methods by which a bacterial cell combats an antibiotic, those methods being:
Limiting the uptake of the drug
Modification of the drug target
Inactivation of the drug
Active efflux of the drug
Let's discuss each one shall we?
Limiting the uptake of the drug:
There are several ways that bacteria limit the uptake of the drug. The first is the outer membrane of the bacterial cell, with mycobacteria possessing an outer membrane with high lipid content greatly limiting access to hydrophilic drugs such as Beta-lactams and glycopeptides. Outer membranes are only prevalent in gram-negative bacteria, so what about gram-positive bacteria?
Well, since gram-positive bacteria do not have an outer membrane, the restriction of drug access is not as common, although there are exceptions such as S. aureus, which has mutated and developed a thickened cell wall that resists antibiotics such as vancomycin much more effectively then before.
Other methods used by bacteria to limit the uptake of the antibiotic are by decreasing the number of porins in the porin channel and making them more selective. As well as the use of biofilms which act as an armor for the bacteria which makes it much harder for the antibiotic to be effective.
Modification of the drug target:
Another trick that bacteria use to fight off is modifying, or more accurately, mutating the target of the antibiotic, thus rendering the antibiotic useless. Oh, you have an antibiotic that targets the ribosomes? Then the bacteria will just mutate the ribosome so the drug can't bind to it. Same thing with drugs that target nucleic acid synthesis, the bacteria will mutate the DNA gyrase so the drug can't bind to it. The bacteria is essentially that kid who changes the rules of the game while playing said game so they always win. Jerk.
Inactivation of the drug:
Bacteria can also inactivate the drug. There are two methods for how they do this. The first method is by actual degradation of the drug. The second method is by transferring a chemical of the drug, those chemicals usually being acetyl, phosphoryl, and adenyl groups.
Active efflux of the drug:
The final method that bacteria use to fight antibiotics is by active efflux, or in a more simple way of putting it, pumping the drug out of the cell. This is performed by chromosomally encoded genes for the efflux pumps, with there being five families of pumps which can filter out different antibiotics. For example, one of these families is the multidrug and toxic compound extrusion (MATE) family. This family of pumps has shown at times to be very good at pumping out members of the aminoglycoside class of antibiotics.
Sun Tzu once said in The Art of War, "If you know the enemy and know yourself, you need not fear the result of a hundred battles." Indubitably, by having a greater understanding of how bacteria defend themselves from our antibiotics, we will have much more success in combating these bacterial viruses in the future. With this information in hand and many more discoveries to be made in the future, perhaps we will one day find a way to defeat our bacterial enemy.
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