Due to an increase in the number of microorganisms that shows resistance to antimicrobial agents, control of various infectious diseases is becoming difficult day by day, resulting in prolonged illness and greater risk of death. When a microorganism is able to survive exposure to an antibiotic, antibiotic resistance occurs.
Antibiotics resistance is a type of drug resistance in which a microorganism becomes resistant to the exposure of antibiotics.
By increasing the duration of exposure of the antibiotic, the risk of the development of resistance increases, regardless of the severity of the need for the antibiotic. Since the resistance towards antibiotics is becoming more common, a greater need for alternative treatments is arising. However, despite the need for new antibiotic therapies, there has been a continued decline in the number of newly approved drugs. Antibiotic resistance, therefore, poses a significant problem.
There are three main mechanisms of bacterial resistance to antibiotics:
Changes in membrane permeability to antibiotics
One of the most common mechanisms, by which the bacteria minimize the effects of antibiotics, is to develop or increase the expression of drug efflux pumps. These efflux pumps expel drugs from the cytoplasm, limiting their ability to access their target.
Alteration of bacterial proteins that are antimicrobial targets
Mutations that cause resistance, can be specific to a particular antibiotic or they can provide protection to multiple often related drugs. A mutation in the genes encoding components of the ribosome that cause extensive changes in the structure of the bacterium, including alterations to several proteins known to causes resistance. These mutations promote further change in the structure of the bacteria in a multi-drug environment and in a drug-specific manner, thus they both provide resistance and increase the chance of resistance.
Enzymatic degradation of antibacterial drugs
Intracellular expression of the drug-metabolizing enzyme deactivates the drug in the immediate environment, thus leading to loss of activity of that drug.
It is important to understand the evolutionary processes of bacterial resistance because antibiotic resistance occurs because of natural selection for resistance-conferring mutations.
Bacteria develops resistance to different antibiotics at different rates. There two properties that determine how quickly resistance will evolve resistance:
The compensatory evolution for multi-drug resistant bacteria compensate is different from that of bacteria resistant to single drug due to the interaction between the resistance mutations.
Resistance to antibiotics is often acquired by the transfer of resistant genes between bacteria and this acquisition is usually facilitated by a conjugative plasmid.
Misuse of antibiotics
The antibiotics resistance is highly associated with underused, overused or misused of antibiotic drugs. This indiscriminate use of antibiotics, promotes antibiotic resistance.
Lack of Culture sensitivity test
Lack of susceptibility testing and inadequate surveillance leads to antibiotic resistance in patients. Unknown susceptibility pattern of bacterial isolates encourages empirical selection of broad-spectrum antibiotics Sometimes Doctors and prescribers are influenced greatly by patients’ demand even if they are sure of their diagnosis.
Noncompliance to drugs
Patient’s incompliance to prescribed drugs is identified as one of the main reasons of resistance to antibiotics. Sometimes patients forget to take their medication and some quit their medication when they start feeling a bit better.
Unaffordability may not allow the patients to complete the course of drugs.
There is irrational use of antibiotics in humans because of self-medication, which includes wrong drug, unnecessary and inadequate dose. Self-medication is also common because antibiotic is being dispensed without prescription.
This is because physicians over prescribe a broad spectrum of drugs when narrow spectrum are appropriate. Prescribers have different variations in the prescribing of antibiotics and other drugs.
Unskilled health practitioners
Wrong prescription and guidelines from unskilled health practitioners also is another important factor.
Hospitals and clinics also contribute to the resistance of antibiotic to microbes. This is as a result of poor infection control practices like hand washing, changing gloves among others.
Poor quality antibiotics
Another issue of poor-quality antibiotics was raised. This is as a result of the use of expired and counterfeit antibiotics, due to lack of quality compliance and monitoring
Use of antibiotics in plants and animals
The irrational use of antibiotics for growth and disease control in animal’s humans indirectly take these antibiotics when we are eating these animals.
We only have a limited set of antibiotics to treat infections, there are various ways of dosing and combining drug regimens that may help to increase drug efficacy and decrease antibiotic resistance. One method is using a
Sequential regimens alternate the use of two or more drugs at a time. In this method sequential regimens could be design which eliminate bacteria at doses that would normally lead to resistance and treatment failure.
A pair of synergistic antibiotics are more effective than the sum of the each efficacy of drugs used.
Antibiotic when used alone and their dual action is thought to be more difficult to overcome. It is difficult to find synergistic pairs because it requires screening of a huge number of drug combinations.
Proper dosing is essential to minimize the development of antibiotic resistance even in single dosage regime.
Synergy between the immune system and the antibiotics
A critically important aspect of the treatment of antibiotic-resistant infections that is usually ignored, is the role of the immune system in clearance because resistant bacteria can be resensitized by treating with a specifically designed anti-sense oligonucleotide treatments that promote synergy between the immune system and the antibiotics.