Infection Control- Chap 18

what does microbiology mean?

Micro means “microscopically small,” and bio means “living organisms

 The two major oral diseases are bacterial infections

◦Dental caries (decay)

◦Periodontitis

Aristotle believed what?

 Believed that life arose from muck, decaying food, warm rain, or even dirty shirts, and that life was “spontaneously generated”.

John Tyndall did what?

Explained the need for prolonged heating to destroy microorganisms.

 Joseph Lister recognized what?

Recognized the role of airborne microorganisms in postsurgical infections

Louis Pasteur is/developed/disproved what?

He is the “Father of microbiology,” developed the process of pasteurization and discovered the first vaccine for rabies. Also disproved the theory of spontaneous generation of life.

Robert Koch is/developed

German scientist, who developed a two-part dish that is used to grow bacteria and a techniques to isolate pure colonies of bacteria.

Koch’s Postulates Guidelines:
(Proved that specific microorganisms caused a particular disease)

 1.The microbial agent must be found in every case of the disease

 2.The microorganism must be isolated and grown in pure culture

 3.The microorganism must cause the same disease when inoculated into a susceptible animal

 4.The same microbial agent must be recovered from the inoculated animal

Koch’s guidelines are still used today to determine the microbial agent, how it grows and the disease.

Major Groups of Microorganisms

 1. Bacteria

 2. Rickettsiae

 3. Algae

 4. Protozoa

 5. Fungi

 6. Prions

 7. Viruses(only can be viewed by a powerful microscope)

Bacteria

are large groups of one-celled microorganisms that vary in shape, size, and arrangements

Pathogenic Bacteria

usually grows best in 98.6°F (37°C) in a moist, dark environment

Normal Flora

Skin, raspatory tract, and gastrointestinal tract are inhabited by a great variety of these harmless bacteria

 Hans Christian Gram developed what?

developed a four-step staining process for separating bacteria into two groups

Three types of Gram

Gram positive bacteria stain by dye(they appear dark purple under the microscope)

Gram negative bacteria does not hold the stain that are stained by the dye

Gram variable bacteria that are not consistently stained are classified as Gram variable (e.g., Mycobacterium tuberculosis)

Capsules

Some types of bacteria form a capsule or protective layer that covers the cell wall (e.g., Streptococcus mutans)

◦Generally virulent (capable of causing serious disease)

◦Capsule increases the bacteria’s ability to resist the defense mechanisms of the body

◦Capsule may also prevent antibiotic agents from having an effect on the bacteria