Antibiotic resistance I Mechanism I Types I Contributing factors.

Antibiotic resistance in bacteria is a global threat of 21st century. Here is a brief discussion of Antimicrobial resistance or Drug resistance disease. If you want to study via video lecture on this visit on my YouTube channel : Microbiology WISDOM:
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1. Presented by: Neha kausar Nasim Sheikh M.Sc. Final (Microbiology) RTMNU Antibiotic Resistance in Bacteria

2. Content Introduction to Antibiotics and Antibiotic Resistance. Types of Antibiotic Resistance. Mechanism of Antibiotic resistance. Factors contributing Antibiotic Resistance.

3. Antibiotics? Medicines used to prevent and treat bacterial infections. Antibiotics are one of our most powerful DRUGS for fighting against life-threatening bacterial infections. Anti- against ; Biotic-living organisms. Antibiotics are derived from a mould or bacterium or produced synthetically.

4. Antibiotics are of two types …

5. Antibiotic Resistance? History With the discovery of antimicrobials in 1940s, scientist prophesied the defeat of infectious disease that had plagued human kind throughout the history. Then the remarkable healing power of antibiotics invites widespread and often inappropriate use. Misuse and Overuse

6. Some organisms have developed resistance to multiple antibiotics and are called as Multi Drug Resistant (MDR) pathogens. Common MDR organisms are usually bacteria. Vancomycin - Resistant enterococci (VRE) Methicillin - Resistant Staphylococcus aureus (MRSA)

7. Why studying Antimicrobial resistance is important? Serious and growing phenomenon in contemporary medicine. Emerged as one of the common public health concern of 21 st century . Worldwide 700,000 people die each year due to Antibiotic resistance-disease, according to WHO. Antibiotic resistance also complicate the care of many Covid-19 patients.i.e.bactria like streptococcus pneumonia complicate viral infections like flu,H1N1 and Covid-19. Early data from china and recent report suggest that a significant percentage of hospitalized patients are developing secondary bacterial infections .

8. Types of Antibiotic Resistance. In this type of resistance Bacteria may be inherently resistant to an antibiotic. Gene responsible for this resistance is call as… Environmental resistome It occurs when a bacterium acquires the ability to resist the action of particular antibiotic. Horizontal gene transfer (Eg: Transformation, Transduction, Conjugation) Spontaneous mutation.

9. Examples of Natural resistance: Streptomyces have some genes which are responsible for resistance to its own antibiotic. Gram – ve bacteria have an outer membrane as a permeability barrier against antibiotic i.e. Penicillin. Organism lacks a transport system for antibiotic. Efflux pumps Lacks the target (i.e. NH mycolic acid synthesis) of antibiotic.

10. Development of Antibiotic Resistance. Mutation and evolutionary pressure cause rapid increase in resistance to antibiotics.

11. Acquired resistance can occur as a result of …. Horizontal gene transfer (Transformation, Transduction , Conjugation) Vertical evolution ( Spontaneous Mutation) A] Horizontal gene transfer: Horizontally transfer a gene between organisms. Involves bacteriophages, plasmids and transposons. Genes that are responsible for antibiotic resistance in one species of bacteria can be transferred to another through various mechanisms. B] Vertical evolution / Spontaneous mutation: Spontaneous mutation occur at relatively low rate. Such mutations have deep effects on resistance of bacterial population to antimicrobial drug. Acquired Antibiotic Resistance.

12. A] Horizontal gene transfer Examples Transformation Transduction Conjugation

13. B] Vertical evolution / Spontaneous mutation Examples Antibiotic resistance to Aminoglycoside streptomycin . Result from a single base pair change in the gene encoding ribosomal protein to which streptomycin binds; the point mutation alters the target and make drug inactive. However, the chance of an organism to develop mutational resistance to multiple drug is extremely low.

14. Mechanism of Antibiotic Resistance Alteration of pathway. Modification of antibiotic target. Decreased uptake of drug.

15. A] Inactivation of Antibiotic: Inactivation involves enzymatic breakdown of antibiotic molecules. E.g.1. Beta- lactumase enzyme: Bacterial gene AmpC codes for Beta lactamase. More than 190 forms of Beta-lactamase. Turned OFF and only Turned ON in presence of B-lactam ring. E.g.2. Aminoglycosidase enzyme: Inactivates Aminoglycoside antibiotic before binding to 30s subunit of ribosome.

16. B] Change in shape of receptor: In this type of mechanism mutation takes place in bacterial cell which alter the drug receptor, so that the drug cannot enter the cell.

17. C] Efflux pumping of antibiotic: They are active against: Beta lactams Fluoroquinolones Tetracycline. Two Types of Efflux pumps: Narrow spectrum (single type of Antibiotic.) Broad spectrum (More than one type of Antibiotic). Antibiotic is pumped out. Cations are pumped in at the same time Also used to remove antiseptic and disinfectant substances. No simultaneous import of cation . Relatively rare. Uses counter flow.

18. D] Alteration of a pathway: Some drug competitively inhibit metabolic pathway of bacteria . To overcome this problem bacteria uses alternative pathway that produce the required product.

19. E] Modification of Antibiotic Target: Bacteria can modify the antibiotic’s target to escape its activity. Bacteria must change structure of target but the modified target must still be able to function. This can be achieved in two ways: Mutation of genes coding for target protein. Importing a gene that codes for modified target.

20. PBPs Enzyme Modification of Antibiotic Target

21. F] Decreased uptake of Drug: Reduce the permeability of membranes to prevent uptake of drug inside the cell. How do they do that? This type of mechanism seen in bacterial resistance to Streptomycin, Tetracycline and Sulfa drugs.

22. Environmental Huge population. Poor sanitization Increased travelling. Drug related Fake drugs Quality of drugs Over the counter availability of action. Over usage. Patient related Poverty. Self-medication. Lack of sanitization. Lack of education. Misconception. Factors contributing Antibiotic Resistance. Physician related Inadequate dosing Lack of current knowledge and training.

23. Thank you.