"Antibiotic" originally referred to a natural compound produced by a fungus or another microorganism that kills bacteria which cause disease in humans or animals.
Though, the development of synthesised compounds due to technological improvements, that can kill or inhibit microbe growth are not specifically "antibiotics" but "antimicrobial agents" (this term may be used to describe both synthetic and natural compounds).
Alexander Fleming discovered the first antibiotic, penicillin, in 1927, though, they were first used in the 1940's.
Examples of natural antibiotics. The bacterial colonies at 10 o'clock, 2 o'clock and 8 o'clock on this agar plate are producing antibiotics that inhibit encroachment by the mould which is growing out from the center.

Their use proved to be so effective, evident in the number of lives that were saved, that they immediately secured an important role in the search for better health.


Infectious: A disease that is caused by a pathogen which can spread from a diseased organism to a non-diseased organism. (e.g. Influenza).
Non-Infectious: A non-infectious disease is a disease that may be caused by the environment (e.g. skin cancer from radiation from the Sun) and not from the transmission of a pathogen*.

*pathogen: an infectious agent (viral, fungal, bacteria, eukaryotic, prionic) that causes disease.


To be considered a useful antibiotic or antimicrobical agent to humans, the compound should:
  • destroy or inhibit a pathogen with minimal or no injury to the host's cells
  • be able to penetrate the host's cells to contact the pathogen
  • not alter the defence mechanisms of the host
  • preferably be effective against many different species of pathogens (broad-spectrum)
  • prevent resistant forms of the pathogen developing easily
  • not cause undesirable side-effects in the host
  • not disturb the balance in the natural microbial communities of the host
- Sakker, Odlam, Garner. Human Disease. 1988

The physical processes that occur when antibiotics are used include:
  • inhibiting cell wall formation of the bacteria
  • damaging the cell membrane
  • interfering with protein synthesis and hence with the metabolic activity
  • inhibiting nucleic acid metabolism (inhibits reproduction)
- Sakker, Odlam, Garner. Human Disease. 1988


CLASS A: Penicillin antibiotics may include:
  • penicillin V (PENVEEK, V-CILLIN)
  • ampicillin (POLYCILLIN, OMNIPEN),
  • and amoxicillin (AMOXIL).

They are used to treat such common infections as:
  • strep throat
  • urinary tract infections,
  • boils and
  • carbuncles,
  • very serious infections including meningitis, pneumonia, typhoid fever.

While the penicillin antibiotics are generally very safe, about 15% of the population is allergic (usually a rash) to this class of antibiotics.

CLASS B: Cephalosporins

They are used to treat:
  • Respiratory Tract infections
  • Urinary Tract infections

Cephalosporins should be saved for cases in which the penicillins cannot be used or are not effective (when a penicillin allergy is evident).

CLASS C: Tetracyclines antibiotics include:
  • doxycycline (VIBRAMYCIN)
  • minocycline (MINOCIN)
  • demeclocycline (DECLOMYCIN).

They are used to treat:
  • Rocky Mountain Spotted Fever
  • Acne
  • The Plague

The tetracycline antibiotics, like the penicillins, are among the most useful and important antibiotics. They are effective against a wide range of bacteria and are therefore considered "broad-spectrum".

CLASS D: Erythromycins antibiotics may include:
  • Erythromycin (E-MYCIN, ILOTYCIN)

It is used to treat:
  • Diptheria
  • Whooping Cough

Erythromycin is probably the second safest antibiotic (after penicillin G) and is a good alternative for people who are allergic to penicillins.

CLASS E: Aminoglycosides and Polypeptides antibiotics include:

They may be used to treat:
  • Cuts and Abrasions (in the form of creams)

The aminoglycoside antibiotics are used almost exclusively in hospitalized patients for serious life threatening infections.
Polypeptide antibiotics are too toxic to be used generally in the body.

CLASS F: Antifungal antibiotics may include:

  • Griseofulvin (GRISACTIN, FULVICIN)

They may be used to treat:
  • fungal infections of the fingernails and toenails


Though generally quite safe, a small percentage of the population may suffer complications with antibiotic use.

Some of the symptoms of adverse reactions to antibiotic use may include (but are not limited to):

    • Resistance developing
    • Diarrhea
    • Stomach discomfort
    • Cramps
    • White patching on the tongue
    • Allergic reactions, including
      • Fainting
      • Vomitting
      • Rashes

If any of these symtoms are noted during the course of an antibiotic/antimicrobial agent use, immediate consultation with a medical practioner is advisable.


1. WHAT was the first antibiotic and when was it discovered?

2. DISCUSS the requirements of an "idea;" anti-microbial drug and explain in what way antibiotics satisfy these requirements.

3. EVALUATE the use of antibiotics in the treatment of disease, in light of the positive and negative aspects associated with thier use.