Bacterial pathogens which were at one time easily treatable with antibodies have reemerged in recent years as highly infectious public health threats. Antibiotic Resistance is a type of drug resistance where a microrganism is able to survive exposure to an antibiotic. These bacterias are able to survive and even divide in presence of an antibiotic. Many bacterias have develop resistance for all major classes of antibodies that are used to treat a wide variety of respiratory, skin and urinary disorders. A bacteria that carry several resistance genes is called as a Multiresistant Organism or a 'superbug'.
Bacteria have evolved numerous strategies for resisting the action of antibiotics. Some of these are given below:
1. By Spontaneous mutation: When a bacteria divide and multiply its genetic material is copied, and sometimes it may result in a mutation. Mutation is a very rare event, the very fast growth of bacteria and the number of cells attained does not take long for resistance to develop in a population.
2. By Inappropriate use of antibiotics: Overuse of antibiotics is one of the main culprit in the creation of 'superbugs'.
(i) In Agricultural and vetenary practices- Use of antibiotics in food producing animals can lead to development of resistance in bacteria. This can effect the treatment of common human infections. for example: Antibiotics are used in large amounts in rearing of fish, it is given to prevent infections and these antibiotics remain in the aquaculture for long time as they are non biodegradable. This encourages growth of bacteria which can survive in presence of Antibiotics and this antibiotic resistance can be transferred to human and animal pathogens, leading to infectious diseases in humans and animals.
(ii) In Medicine: In medical environments, use of antibiotics is very intensive and this causes bacteria to acquire the means by which they become resistant to Antibiotics.
3. By Horizontal Gene Transfer: Antibiotic Resistance genes can be transferred between bacteria of same species or different species in a horizontal fashion by either of the three mechanisms of gene transfer- conjugation, transformation and transduction. Conjugation is the main mechanism of Horizontal Gene Transfer.
MULTIDRUG RESISTANT ORGANISM (MRDO):Multi Drug Resistant organisms are resistant to treatment with several unrelated antibiotics. Some of the MDR organisms are:
- Methicillin Resistant Staphylococcus aureus (MRSA)
- Vancomycin Resistant Enterococcus (VRE)
- Penicillin Resistant Streptococcus pneumonia (PRSP)
Methicillin Resistant Staphylococcus aureus: S.aureus is one of the major resistant pathogen found on the anterior nares (nostrils), mucous membranes and human skin. MRSA are resistant to the action of methicillin and beta lactum antibiotics. Patients with open wounds and weak immune system are at a greater risk of infection due to MRSA.
Community Associated- MRSA are localized to skin and softer tissues and often cause infections like a pimple in healthy individuals which don't have risk factors.
Hospital Acquire- MRSA occur when staphylococci can get through the skin and affect vital organs causing infections like sepsis, pneumonia, etc.
Vancomycin Resistant Enterococcus: These bacterial strains are resistant to antibiotic vancomycin. They contain DNA that encodes genes conferring Vancomycin Resistance.VRE can cause meningitis, pneumonia, endocarditis, etc.
PREVENTION: Few measures can be adapted to prevent the development of Antibiotic Resistant strains:
- Overuse and misuse of antibiotics should be avoided.
- Antibiotics do not work against cold and flu (as they are caused by viruses), so do not take antibiotic unless you have a specific bacterial infection.
- When Antibiotic is prescribed, its dosage must be completed.
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M.Sc Biotechnology student from Hyderabad, India