Infectious Disease 1

Question 1

What are the 4 main infectious agents?

(think about size)

Answer 1

• Protozoa single celled animals, eukaryotes
• Fungi higher plant like organisms, eukaryotes
• Bacteria generally small, single celled prokaryotes
• Viruses very small obligate parasites, non-living

Question 2

What are the names of the 4 different case studies on the histories of infectious diseases and their year?

Answer 2

• Infection Control (1840s) • Semmelweis
• Germ Theory (1860s) • Pasteur
• Antiseptics (1870s) • Lister
• Germ theory of Disease (1880s) • Koch

Question 3

What is Kochʼs postulates -Germ Theory of Disease?

Answer 3

(The microorganism is present in every case of the disease but absent from healthy organisms)

• The suspected organism must be isolated and grown in a pure culture
• The same disease must result when the isolated microorganism is introduced into a healthy host
• The same microorganism must be isolated again from the diseased host.
• The Ab to the organism should be detected in the patientʼs serum

Question 4

What does a bacteria gram positve stain have?

Answer 4

-THICK peptidoglycan

• techoic acid
• lipotechoic acid

Question 5

What does a bacteria gram negative stain have?

Answer 5

• THIN layer peptidoglycan
• Outer membrane of phospholipids which have transport membranes
• lipids embedded into it.
• Last layer = lipopolysaccharide (LPS)

LPS DIAGRAM

Question 6

Are endotoxins present in gram +ve or gram -ve bacteria?

Answer 6

gram -ve

Question 7

What are atypicals?

Answer 7

atypicals do not have any petiloglycan in their cell walls so will not show any colour when stained.

Question 8

What are the following:

pathogen

commensal/symbiont

opportunistic pathogen

contaminant

Virulence

Answer 8

Pathogen

-a harmful organism that produces a pathology • Virulence, & virulence factors

• Commensal/Symbiont

• how an organism relates to the host and offers a mutal reaction with host • endogenous

• Opportunistic pathogen

• an organism that causes infection when opportunity/change in natural immunity arises • e.g. in an immunocompromised individual

• Contaminant

• an organism that is growing in a culture by accident

• Virulence

• The capacity of a microbe to cause damage to the host

Question 9

What is Exogenes and Endogenes

Answer 9

exogenes= infection material from outside body

endogenes= Bacteria/Fungi part of natural microbiome (commensal)

Question 10

What is the oral cavity dominated by?

Answer 10

Streptococci

Question 11

What is the Ecology of Bacteria?

Answer 11

Free-Living - Saprophytic (feed on dead organic material)

Commensal - organism gains advantage but host does not gain from association.

Mutualistic - (or symbiotic) relationship, when host & organism gain mutual value

Parasitic - live on or in living creatures causing harm/damage to the host

Question 12

What are the 4 types of ways for disease to spread?

Answer 12

Direct Spread/contact vertical or horizontal

• Indirect Spread Formite (dental instrument)
• Air-borne spread Droplets/aerosols
• Vector-borne spread Insects

Question 13

What is Epidemiology?

and the 4 different occurences?

Answer 13

Epidemiology = The study of the occurrence, spread and control of disease

• Sporadic
• Endemic
• Epidemic
• Pandemic