Drug resistance can occurs when bacteria, viruses, or parasites become resistant to the drugs that are designed to treat them. When a pathogen is exposed to a drug, it can develop mutations that make it less susceptible to the drug’s effects. Over time, these mutations can lead to the emergence of drug-resistant strains of the pathogen. Overuse of antibiotics, poor sanitation, and the spread of resistant strains between people and animals can make drug to be resistance . When Drug is resistance is a growing public health concern, because make treating infections can be more difficult and expensive.
- When pathogen prevent the entry of the drug e.g many of gram positive bacteria unaffected by the penicillin G. Because;
a. It cannot penetrate the out membrane of the cell.
b. It changes the penicillin binding protein, thus renders a cell resistant.
c. It decreases permeability of the cell
d. Resistance to tetracycline can result from plasmid encodes protein that pump the drug out of the cell.
2. Drug may be inactivated through chemical modification. E. g hydrolysis of Beta ring by the enzyme penicillin are.
3. The drug can also be inactivated by addition of group. That is resistant organisms can phosphorylation examples in aminoglycoside, acetylene can be added which prevent the effect of chloramphenicol.
4. Resistance may be due to modification of specific target of enzymes or the organelles. E. G the antifungal ribosome for erythromycin and chloramphenicol can be decreased by change in 23s rRNA to which they bind.
5. It could be through the use of an alternative pathway to by pass the sequence of inhibition. E. g. Some bacteria are resistant to sulfa amide because they use a pre formed folic acid from thier surrounding rather than synthesizing it themselves, thus drug targeting folic acid synthesis is rendered useless.