POST-RN Helpful tool for learning pharmacology according to HEC Curriculum.

1. ANTIMICROBIAL DRUGS
MAHNOOR FATIMA

2. OBJECTIVES
By the end of this unit students will be able to:
• Discuss and review common terms and concepts
related to antimicrobial therapy.
• Discuss mechanism of action and indication of
using antimicrobial therapy.
• State appropriate nursing implications for a client
receiving antimicrobial drugs.
• Discuss general principles and consideration
related to antimicrobial therapy.

3. Antimicrobial drugs
Antimicrobial drugs are chemical substances of natural or synthetic origin that
suppress the growth of, or destroy, micro-organisms including bacteria, fungi,
helminthes, protozoa and viruses. OR
The drug used to prevent the pathogenicity of microorganisms is called an
antimicrobial agent.
FOR EXAMPLE
Bacterial pneumonia
Sepsis (bloodstream infections)
Wound and bacterial skin infections
Urinary tract infections
Bacterial tonsillitis (strep throat)

4. Antimicrobial Terminology
• Antibiotic: Used to treat and cure infectious diseases caused
by bacteria and are considered nontoxic to the host.
• Antibacterial: Inhibits the development and reproduction of
bacteria.
• Antifungal: Inhibits the development and reproduction of fungi
and spores.
• Antiviral: Inhibits the development and transmission of
viruses. Antiviral drugs taken internally are considered
nontoxic to the host and target pharmacologically precise
targets (ie. viral proteins or parts of viral proteins).

5. Continue....
• Disinfectant: Chemical substances that are applied to
inanimate objects and/or surfaces to kill microbes (includes all
bacteria, archaea, and fungi). Examples: mercury dichloride,
phenol. Disinfectants do not necessarily kill bacterial spores.
• Fungicide: A chemical substance used to kill or destroy fungal
particles.
• Antiseptic: An antimicrobial substance that is applied to
living tissue and/or skin to prevent, treat, and/or reduce
infection.
• Germicidal: working definition in progress

6. Continue....
• Microbicide: A chemical agent that is used to kill bacteria, fungi, and
viruses.
• Preservative: An additive to products (food, cosmetics, etc) used to
inhibit the growth of microorganisms.
• Sanitizer: A method or chemical used to clean surfaces, which
inadvertently kills some microorganisms, but not all.
• Sterilizer: A method or chemical used to free surfaces of all live
microorganisms. Sterilization does not necessarily destroy prions.
• Viricide: A chemical agent used to deactivate or destroy virus particles.

7. Concept Of Bacteriostatic & Biocidal:
• Bacteriostatic: “bacteriostatic” means that the agent prevents the
growth of bacteria.
• Biocidal: “bactericidal” means that it kills bacteria.

9. SELECTION OF APPROPRIATE ANTIBIOTIC
Selection of the most appropriate antimicrobial agent
requires knowing
• The organism’s identity
• The organism’s susceptibility to a particular agent
• The site of the infection
• Patient factors
• The safety of the agent
• The cost of therapy

10. Organism’s identity
Direct microscopic visualization
Cultivation and identifcation
Detection of microbial antigens
Detection of microbialRNA or DNA
Detection of host 5 immune response
Empiric therapy (prior to identification of the of organism)
Timing:Acutely ill patients with infections of unknown origin—for example, a
neutropenic /meningitis patientrequire immediate treatment. If possible, therapy
should beinitiated after specimens for laboratory analysis have been obtainedbut
before the results of the culture and sensitivity are available.
Selecting a drug:Drug choice in the absence of susceptibility data is influenced by
the site of infection and the patient’s history(for example, previous infections, age,
recent travel history, recent antimicrobial therapy, immune status).

11. Antimicrobial Susceptibility of Infective Organisms]
Bacteriocidal & Bacteriostatic
Minimum inhibitory concentration: The minimum inhibitory concentration (MIC) is
the lowest antimicrobial concentration that prevents visible growth of an organism
after 24 hours of incubation.
Minimum bactericidal concentration: The minimum bactericidal concentration
(MBC) is the lowest concentration of antimicrobial agent that results in a 99.9%
decline in colony count after overnight broth dilution incubations.
Effect of the site of infection on therapy: the blood–brain barrier
Lipid solubility of the drug: chloramphenicol & Metronidazole,have significant
penetration into the CNS than penicillin.
Molecular weight of the drug: A compound with a low molecular
weight has an enhanced ability to cross the blood–brain barrier(vancomycin)
Protein binding of the drug: A high degree of protein binding rather (unbound)
of a drug restricts its entry into the CSF. Therefore, the amount of
free drug in serum.

12. Patient factors
• Immune system,
• Renal dysfunction/Hepatic dysfunction,
• Poor perfusion
• Age
• Pregnancy and lactation
Safety of the agent
Antibiotics such as the penicillins are among the least toxic of all
drugs Other antimicrobial agents (for example, chloramphenicol) have less
specificity and are reserved forlife-threatening infections because of the potential
for serious toxicity to the patient.
Cost of therapy
Often several drugs may show similar efficacy in treating an infection
but vary widely in cost.It is also important toconsider the cost of the medication

13. INDICATION FOR ANTIMICROBIAL
THERAPY(Prophylactic Treatment)
Pretreatment may prevent
1. Streptococcal infections(rheumatic heart disease).
2. Undergoing dental extractions.
3. Tuberculosis or meningitis (who are in close contact).
4. Who have implanted prosthetic devices(artifcial heart valves)
5. Prevents seeding of the prosthesis.
Treatment prior to most surgical procedures can decrease the
incidence of infection afterwards.

14. INDICATION FOR ANTIMICROBIAL THERAPY

15. Classification of Antimicrobial Agents
Antimicrobial agents can be divided into groups based on the mechanism of
antimicrobial activity.
 Agents that inhibit cell wall synthesis
 Depolarize the cell membrane
 Inhibit protein synthesis
 Inhibit nuclei acid synthesis,
 Inhibit metabolic pathways in bacteria

16. MECHANISM OF ACTION FOR ANTIMICROBIAL
THERAPY

17. Appropriate Nursing Implications For a Client
Receiving Antimicrobial Drugs
• Prevent the spread of bacteria between patients;
• Prevent infections related to surgery and/or placement of a catheter; and
• Improve antibiotic use through stewardship
• Assessment of Response to Treatment
• Adeverse Effect
• Prevent Emergence of Resistance
• Use of Therapeutic Drug Monitoring
• void in pregnancy and lactation.
• Monitor for signs and symptoms QT prolongation, tendon rupture, and
bleeding in elderly and renally impaired clients.
• Avoid with antacids or multivitamins as these may reduce the efficacy of the
antibiotic increasing resistance
• Use of Aseptic Techniques

18. Stewardship

19. Antibiotics Spectrum
Narrow-spectrum antibiotics
Chemotherapeutic agents acting only on a single or a limited group o
fmicroorganisms are said to have a narrow spectrum.
For example, isoniazid is active only against Mycobacterium tuberculosis
Extended-spectrum antibiotics
Extended spectrum are to be effective against gram-positive organisms and
also against asignificant number of gram-negative bacteria.
For example, ampicillin
Broad-spectrum antibiotics
Drugs affect a wide variety of microbial species and are referred to asbroad-
spectrum antibiotics.
For example tetracycline, fluoroquinolones and carbapenems
Administration of broadspectrum antibiotics can drastically alter the nature of
the normal bacterial flora and precipitate a superinfection in individual.

20. General Principles and Consideration Related to Antimicrobial Therapy
Important considerations when prescribing antimicrobial therapy include
• Obtaining an accurate diagnosis of infection
• Understanding the difference between empiric and definitive therapy
• Identifying opportunities to switch to narrow-spectrum
• cost-effective oral agents
• Interpretation of susceptibility result
• Bctericidal Vs Bacteriostatic
• Use of Antimicrobial Combinations
• Prevent Emergence of Resistance
• Host Factors to Be Considered in Selection of Antimicrobial Agents
• Use of Therapeutic Drug Monitoring
• Duration of Antimicrobial Therapy
• Assessment of Response to Treatment
• Adeverse Effect

21. THANK YOU