1. SPECIFIC OBJECTIVES
By the end of this presentation learners should be able to;
Define drug resistance (Introduction)
Describe the types of drug resistance
Explain the causes of drug resistance
Explain the mechanism of drug resistance
Describe some of the reasons why there is a rise in drug resistance
Describe the strategies used in the reduction of drug resistance
2. Introduction
The term “Drug resistance” is the reduction in the effectiveness of a drug such as an
antimicrobial, anthelmintic or an antineoplastic in curing a disease or condition.
(Fischer Jed F, 2010)
OR
The ability of bacteria and other microorganisms to withstand a drug that once stalled
them or killed them.
The term is commonly used in the context of resistance that pathogens have acquired,
that is, resistance has evolved.
3. TYPES OF DRUG RESISTANCE
ANTIBIOTIC RESISTANCE
This involves the pneumococcal conjugate vaccine (PCV) that is
effective tool that prevents infections. It has not only reduced the
burden of invasive pneumococcal disease, but it takes also reduced
antibiotic resistance by blocking the transmission of resistant
streptococcus pneumonia straws.
E.g. streptococcus pneumonic is resistant to penicillin and other beta –lactams
ANTIVIRAL RESISTANCE
Resistant strains of the virus e.g. HIV due to use of only one antiviral drug.
4. ANTIFUNGAL RESISTANCE
Resistant strains of fungus e.g., candida, aspergillus may become resistant to some antifungal
drugs.
ANTIPROTOZOAL RESISTANCE
This is when protozoa becomes resistant to antiprotozoal drugs for
example plasmodium may become resistant to Lumefantrine
Artemether…
5. CAUSES OF DRUG RESISTANCE
NATURAL (BIOLOGICAL) CAUSES
In the presence of an antimicrobial drug, microbes are either killed or if
they carry resistance genes, survive.
The survivors will replicate and their progeny will quickly become the
dominant type throughout the microbial population.
MUTATION
Most microbes reproduce by dividing every few hours, allowing them to
evolve rapidly and adapt quickly to new environment condition. During
replication mutations arise and some of these mutations may help an
individual microbe survive exposure to an antimicrobial.
6. GENE TRANSFER
Microbes also may get genes from each other, including genes that make the microbe drug
resistance.
INAPROPRIATE USE
This may arise due to use of broad spectrum antimicrobials in conditions where use of narrow
spectrum antimicrobials may be effective.
7. AGRICULTURAL USE
Scientists also believe that the practice of adding
antibiotics to agricultural feed promotes drug
resistance.
8. INADEQUATE DIAGNOTICS
Health care providers incomplete or imperfect information to diagnose an infection and thus
prescribe ant microbial just-in-case or prescribe a broad spectrum antimicrobial when a specific
antibiotics might be better.
HOSPITAL USE
Critically ill patients are more susceptible to infection. The extensive use of antimicrobials and
close contact among sick patients creates a fertile environment for the spread of antimicrobial
resistant germs
9. MECHANISMS OF DRUG RESISTANCE
There are three stages in the mechanism of drug resistance;
A. Alteration of the target site
B. Alteration of access to target site
C. Production of enzymes which modify or destroy the antibacterial
10. A. Alteration of the target site
Target may have lowered affinity for antibacterial but still functions for normal
metabolism
Production of an additional target (e.g. enzyme)
11. B. Altered access to target site
Altered uptake- This involves the decreased permeability of the drug across a cell membrane.
Increased exit- This involves the pumping out of the drug (efflux mechanism)
12. C. ENZYME PRODUCTION
For example Beta Lactamase (Penicillinase) enzymes which destroys natural
penicillin G.
13. THE RISE IN DRUG RESISTANCE
There is a rise in cases of drug resistance. Some of the reasons why there is this rise in drug
resistance include:
The widespread use and misuse of drugs- An example of such a drug that has a resulted in the rapid increase in
prevalence and complexity of its resistance as a result of its widespread use and misuse is Penicillin.
International travelling- International travelling plays a very big role in the rising cases of drug resistance. For
example when one is travelling from Europe to Africa, that is in the Southern part of Africa where there is high
risk of malaria, the person is administered a malaria prevention drug; that is Chemoprophylaxis prevention
which includes chloroquine. And due to the widespread of chloroquine a resistance to it has developed in the
parts of central Africa.
Availability of over-counter drugs
Inappropriate doses
14. STRATEGIES TO REDUCE DRUG
RESISTANCE
Antimicrobial drugs should only be used when
necessary
Antimicrobial drugs should be give in adequate
dose-
The use of antimicrobials e.g. antibiotics by
farmers to promote animal growth should be
strictly controlled as it has led to the emergence
of resistant strains of bacteria.
In certain circumstances e.g. the treatment of
tuberculosis the use of several antibiotics together
15. The use of antibiotics prophylactically is generally to be deplored as is usually breeds
resistant strains, however there are exceptions to this rule when the patient is at high
risk of developing severe infections.
16. SUMMARY
Drug resistance is the reduction in effectiveness
of an antimicrobial drug.
Examples of resistance include antiviral,
antiprotozoal and antifungal resistances.
Antimicrobials should be used with caution to
avoid drug resistance.
