We Know: All About Antibiotics

What are antibiotics?

Antibiotics are soluble substances that are developed from mold or bacteria and used to treat infections. Antibiotic drugs that kill or stop bacteria are called bactericidal drugs. Those that slow the growth of bacteria are called bacteriostatic. Patients with pneumonia, tuberculosis, and meningitis are treated with these types of drugs.


Antibiotics are effective against infections caused by bacteria, but are ineffective against virally caused illnesses such as cough, cold, and flu.

How do they work?

Antibiotics act on specific sites of a bacterial cell to stop growth. These sites include:

  • Bacterial cell wall
  • Bacterial protein synthesis to inhibit the manufacture of bacterial proteins
  • Plasma membrane

What are the different types of antibiotics?

Antibiotics are made synthetically (i.e. trimethoprim) and from living microorganisms (i.e. penicillin, erythromycin, and amoxicillin). They come in two basic flavors:

  • Narrow Spectrum Antibiotics - these drugs work on a selective range of microorganisms
    • Gram positive - such as penicillin
    • Gram negative - such as aminoglycosides
  • Wide Spectrum Antibiotics - these antibiotics work on both gram positive and gram negative bacteria
    • Tetracycline
    • Chloramphenicols

Antibiotics may be taken orally, intravenously for more serious infections, and topically, in the form of drops for infections of the eyes and ears.


The effectiveness of the antibiotics depend on where the infection occurs, and whether or not the antibiotic can reach the area of infection. If an organism develops antibiotic resistance, traditional treatments become ineffective at stopping the bacteria.

When will I need antibiotics?

You should take antibiotics for bacterially-caused infections, such as some ear and sinus infections. Never take antibiotics for virally-induced infections.

What are the side effects of taking antibiotics?

Commonly encountered side effects include headaches, allergies, and possible diarrhea from antibiotics that disturb the good bacteria lining the intestinal tract. Taking too many antibiotics can result in antibiotic resistance. There is an increased risk of antibiotic resistance occurring when we consume meats since antibiotics are used with farm animals to promote faster rates of growth.

What should I do when a doctor prescribes antibiotics?

Follow the doctor's orders with any antibiotic. The DOs include:

  • Take the antibiotic as prescribed by the doctor
  • Take the antibiotic at the prescribed time and dosage, even if you are feeling better
  • Discard leftover medicines to prevent misuse

What is antibiotic resistance?

An antibiotic is effective when it destroys close to 100% of the microorganisms causing the infection. If some of the bacteria survive the drug's effects, they may reproduce and mutate to the point that they're resistant to traditional modes of treatment. Frequent use of some antibiotics has produced resistant strains of bacteria to these drugs, which means that bacteria multiply much more quickly in the body. Strains that have become resistant include Staphylococcus aureus (penicillin resistant), Pneumacocci, Salmonella, and Vancomycin-resistant Enterococci.



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