PHM-308
(PHARMACOLOGY AND THERAPEUTICS-IIB)
CHEMOTHERAPY
COMMON TERMINOLOGIES
1. ANTIBIOTIC
Greek words anti (against) and biotikos (concerning life) refers to substances produced by
microorganisms, which selectively suppress the growth or kill other microorganisms at very
low concentration.
2. CHEMOTHERAPEUTIC AGENTS
The use of drugs (chemical entity) with selective toxicity against infections/viruses, bacteria,
protozoa, fungi, and heminths.
3. ANTIMICROBIAL
Derived from the Greek words anti (against), mikros (little) and Bios (life)
It refers to all agents of natural, synthetic, or semi-synthetic origin which at low concentrations
kill microbes, inhibits (or slows) the growth of microorganisms or prevent the pathogenic
action of microbes but causes little or no host damage. Antimicrobials include both
Chemotherapeutic agents and antibiotics.
4. ANTIBACTERIAL
Inhibits the development and reproduction of bacteria.
5. ANTIFUNGAL
Inhibits the development and reproduction of fungi and spores.
6. ANTIVIRAL
Inhibits the development and transmission of viruses.
7. SPECTRUM
The term spectrum refers to the range of activity of an antibiotic agent against various bacterial
species, or groups of species (e.g. Gram-positive, Gram-negative, aerobic, facultatively
anaerobic, obligate anaerobes).
The range of an antimicrobial’s effectiveness, i.e. able to kill multiple types of microbes or
specialized to target one type of organism.
8. BROAD-SPECTRUM ANTIBIOTIC
Antibiotics that work against a wide range of Gram-positive and Gram-negative bacteria.
9. EXTENDED-SPECTRUM ANTIBIOTIC:
Antibiotic can kill or inhibit Gram positive bacteria and some Gram-negative bacteria.
10. NARROW-SPECTRUM ANTIBIOTIC:
Antibiotic can only kill or inhibit limited species of bacteria. (Gram-positive or Gram-
negative bacteria).
11. SUSCEPTIBLE MICROORGANISM/MICROBE
Microbes that are vulnerable to the therapeutic effect of antimicrobials, i.e. they are
destroyed by antimicrobials.
12. ADDITIVE EFFECTS
The additive effect of a combination of antibiotics is one in which the effect of the combination
is equal to that of the sum of the effects of the individual components.
13. SYNERGISM
Synergistic action of a combination of antibiotics is present if the effect of the combination
exceeds the additive effects of the individual components.
14. ANTAGONISM
Antagonism is present if a reduced effect of a combination of antibiotics is observed in
comparison with the effect of the most effective individual substance.
15. ANTIBIOTIC / NATURAL RESISTANCE:
Innate ability of a bacterial species to resist activity of a particular antimicrobial agent through
its inherent structural or functional characteristics, which allow tolerance of a particular
antimicrobial drug or class.
The genetically-acquired capacity for bacteria to withstand antibiotic treatment.
16. ACQUIRED RESISTANCE
When a particular microorganism obtains the ability to resist (prevent/inhibit the action) a
particular antimicrobial agent to which it was previously susceptible.
17. MULTIPLE-DRUG RESISTANCE
A phenomenon when one or more micro-organism is resistant to the effects of more than one
antimicrobial drug (i.e. the drug no longer works to kill the microbe).
18. MULTI-DRUG RESISTANT ORGANISM
A microbe that is resistant to the effect of more than one antimicrobial drug, i.e. multiple
distinct drugs do not kill the microbe.
19. EFFLUX PUMP
A resistance mechanism that allows bacteria to pump out any antibiotics that penetrate them.
20. Drug Tolerance
The diminished response of the patient to the effectiveness of the drug when a drug is used
repeatedly.
21. ANTISEPTIC
An antimicrobial substance that is applied to living tissue and/or skin to prevent, treat,
and/or reduce infection.
22. DISINFECTANT
Chemical substances that are applied to objects and/or surfaces to kill microbes
23. ANTIMICROBIAL SUSCEPTIBILITY TESTS
The tests used to determine which specific antimicrobials a particular pathogen is sensitive.
24. COMBINATION THERAPY
Treatment involving more than one drug. A rationale for use of combination therapy has been
the lesser likelihood that a pathogen develops resistance to multiple drugs.
25. COMMUNITY-SETTING
Refers to where antimicrobials are used or prescribed outside of a hospital or emergency-room
setting; for example, a private medical or veterinary clinic, pharmacies, or public health centers.
26. COMMUNITY-ACQUIRED INFECTION
Infection acquired in the community by someone who has not been recently hospitalized nor
had a recent medical procedure.
27. NOSOCOMIAL INFECTION
An infection acquired in the hospital, excluding infections incubating at time of admission.
28. GRAM STAIN
A laboratory staining technique used to distinguish between two groups of bacteria, Gram-
positive and Gram-negative that differ in their cell wall structure.
29. PROPHYLAXIS
Administration of an antimicrobial to exposed healthy humans considered to be at risk for
developing a disease, but prior to the onset of the disease symptoms and for which no etiologic
agent has yet been confirmed by culture or other detection methods.
Prevent an initial infection or its recurrence after infection.
30. METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA)
A type of Staphylococcus aureus bacterium resistant to methicillin and other beta-lactam
antibiotics. No longer confined to hospitals, MRSA has caused infectious outbreaks in
community groups.
31. OPTIMAL DURATION TREATMENT
The ideal length of time for treatment with antimicrobials to prevent disease relapse and
antimicrobial resistance, and also to ensure patient safety and cost-effectiveness.
32. SELECTIVE TOXICITY
A drug’s ability to target pathogens such as bacteria or viruses without damaging the host
organism.
33. BACTERICIDAL ACTIVITY
The drugs that kill or irreversible damage the multiplying (proliferating) bacteria to decrease
the number of viable organisms. (kill the microbes)
34. BACTERIOSTATIC ACTIVITY
The drugs that arrest the growth and replication of the bacteria and thus limit the spread of
infection. (inhibit the growth of bacteria).
Prevents or suppressed the growth of bacteria, but does not destroy bacteria.
35. SUPERINFECTION
A new infection occurring in a patient having a pre-existing infection. Superinfections are
most difficult to treat.
36. EMPIRIC THERAPY/TREATMENT
The anti-microbial therapy when infecting organism is not identified . (more of broad
spectrum).
A diagnosis or treatment on the basis of a clinical educated guess in the absence of complete
or perfect information. Clinicians use their expertise, intuition and professional judgement to
‘guess’ whether an infection is present and what is likely to be causing it, and thus the most
appropriate treatment.
37. DEFINITIVE THERAPY/TREATMENT
The antimicrobial therapy when infecting organism is identified, and specific therapy
chosen (more of Narrow spectrum)
38. INDICATION of a drug
A medical condition for which the drug (medicine) is intended to be used.
Fever ……….. Paracetamol
Hypertension………… beta blockers
39. PRECAUTION
It is a measure (action) taken in advance to prevent something dangerous or
unpleasant from happening when a drug is administered.
Children…..Viral disease present or not present……..Aspirin (Reye´s syndrome)
Fever and pain…. History of allergy to Ibuprofen (Asprin: cross-reactive allergy with NSAIDs)
Fever and pain…..Pre-existing Peptic ulcer disease present or not……. (Aspirin; GI bleeding)
Hypertension…….patient has Asthma problem or not….(beta blockers; bronchoconstriction)
40. CONTRA-INDICATION of a drug
A specific situation (symptom or medical condition) that makes a particular treatment or
procedure inadvisable because it is likely to harmful to the person.
Viral infection in children…… (Aspirin……. Reye´s syndrome)
Allergy to Ibuprofen……………… (Asprin……cross-reactive allergy)
Peptic ulcer disease ………………. (Aspirin……..GI bleeding)
Asthmatic patient…………………….(beta blockers…….bronchoconstriction)
41. MINIMUM INHIBITORY CONCENTRATION (MIC)
The lowest (minimum) concentration of antibiotic that inhibits bacterial growth.
42. MINIMUM BACTERICIDAL CONCENTRATION (MBC)
The lowest (minimum) concentration of antibiotic that kills bacteria under investigation.
Learning outcomes / Concepts in antimicrobial therapy
1. Anti-microbial vs Chemotherapeutic agents vs Antibiotics
2. Antibiotic spectrum and types.
3. Natural resistance vs acquired resistance
4. Multi drug resistance vs multi drug resistance organism
5. What is susceptibility and susceptibility tests
6. Drug Tolerance vs Drug Resistance
7. Combinational therapy and types of effects
8. Community-acquired vs nosocomial (hospitalized) infections
9. Prophylaxis vs Precaution
10. Empiric vs Definitive treatment
11. Indications vs Contra-indications with examples
12. Contra-indication vs precaution
13. Bactericidal vs Bacteriostatic activity
14. MIC vs MBC
BACTERIOSTATIC ACTIVITY
The drugs that arrest the growth and replication of the bacteria and thus limit the spread of
infection. (inhibit the growth of bacteria).
Commonly used for uncomplicated infections (host immune system support)
Examples Macrolides, Chloramphenicol, Tetracycline, Erythromycins, Sulphonamides,
Trimethoprim
Minimum inhibitory Concentration (MIC)
BACTERIOCIDAL ACTIVITY
The drugs that kill or irreversible damage the multiplying (proliferating) bacteria to decrease
the number of viable organisms. (kill the microbes)
Bactericidal antimicrobials: (for complicated infections)
Penicillins, Aminoglycosides, Vancomycin, Ciprofloxacin, Co-tromoxazole, Metronidazole,
Rifampin, Isoniazid.
Minimum Bactericidal Concentration (MBC)
Some act as both: Chloramphenicol (static against gram -ve rods, while -cidal against S.
pneumoniae)
