Bacteria and Antibiotics

Mrs. StewartMedical InterventionsCentral Magnet School

Bacteria

GRAM --

Thin layer of peptidoglycan

Lipopolysaccharides (endotoxins)

Stain red

GRAM +

Thick layer of peptidoglycan

Stain blue

Neisseria Meningitidis

GRAM -

What Are Antibiotics?

A substance produced by or derived from a microorganism and able in dilute solution to inhibit or kill another microorganism

Antibiotics are drugs used to treat infections caused by bacteria.

Alexander Fleming – 1930’s

Penicillin

Where Do Antibiotics Come From? The early antibiotics were the natural

products of other microorganisms – fungi or other bacteria.

All are now manufactured either by chemical synthesis or bioengineering.

Newer antibiotics have also been created completely synthetically, usually by altering the chemical structure of an existing, naturally produced antibiotic.

Gangrene and Antibiotics - WWII

Would have to cut legs off after war wounds became infected

Began treating infections from wounds w/ antibiotics

World War II "If any good can be said to come of war, then

the Second War War must go on record as assisting and accelerating one of the greatest blessings that the 20th Century has conferred on Man - the huge advances in medical knowledge and surgical techniques. War, by producing so many and such appalling casualties, and by creating such widespread conditions in which disease can flourish, confronted the medical profession with an enormous challenge - and the doctors of the world rose to the challenge of the last war magnificently."

-Brian J Ford.

How Do Antibiotics Work?

Bactericidal – Kills the bacteria

Bacteriostatic – inhibits growth & reproduction

* The body’s natural defenses can usually take it from there

Beta – Lactam Abx

Disrupt the synthesis of peptidoglycan thereby inhibiting cell wall synthesis

Fluoroquinolones

Inhibit DNA replication – prevents cell division

Inhibits transcription – prevents protein synthesis

Tetracyclines

Bind the ribosomal subunit, blocking the attachment of tRNA, thereby inhibiting protein synthesis

Sulfa (sulfonamides)

Folate synthesis inhibitors – folate is necessary for DNA synthesis

Prevents cell division

What type of infection is it?

Antibiotics target bacteria and a few parasites.

However, they are not effective against viruses.▪ Most upper

respiratory tract infections (common cold, sore throats, etc) are caused by viruses

Why not take antibiotics no matter what kind of

infection you have? Covers all possible bases,

right?

WRONG!!Why??If antibiotics are overused or used incorrectly, there is a chance that the bacteria will become resistant ▪That means the antibiotic becomes less effective against that type of bacterium

Examples:

Ear Infections

MRSA

TB – Tuberculosis

Strep throat