Microbial Infection

Question 1

Viruses

Answer 1

Not cells in own right

Replicate using host-cell nuclear synthetic machinery

Show host specificity

Divide by budding out of host cells or cytolisis

Routes of infection - faecal-oral, airborne, insect vectors, blood borne

Question 2

Examples of virus

Answer 2

HIV - Retrovirus

Question 3

Bacteria - prokaryotes

Answer 3

Do not have internal membranes

Single copy of a chromosome —> haploid

Cytoskeleton poorly defined

Cell wall contains peptidoglycan

Divide by binary fission

Question 4

Example of bacteria

Answer 4

Shigella
- infectious dose 10- 100 bacteria
- faecal-oral transmission

Neisseria meningitidis
- community acquired
- multiple serogroups
- rapid progression
- septic shock
- severe inflammatory response

E. coli

Question 5

Fungi

Answer 5

Eukaryotic

Cause cutaneous, mucosal and/or systemic mycoses

Occur as yeast, filaments or both

Yeast bud or divide; filaments (hyphae) which have cross walls or septa

Question 6

Fungi example

Answer 6

Candida albicans

Question 7

Protozoa

Answer 7

Unicellular eukaryotic organism - include intestinal, blood and tissue parasites

Replicate in host by binary fission or by formation of trophozoites inside a cell

Many have complicated lifestyle including 2 hosts

Infection acquired by ingestion or through a vector

Question 8

Protozoa example

Answer 8

Malaria
- via mosquito vector
- blood and tissue parasite
- formation of trophozoites inside a cell

Leishmania species
- via sandfly vector
- “ “

Question 9

Helminths

Answer 9

Métazoaires with eukaryotic cells

Multi-cellular

Life cycle outside the human host

Question 10

Helminths example

Answer 10

Roundworms

Flatworms

Tapeworms

Question 11

What does effective treatment of infection require?

Answer 11

Knowledge of causative agent:

• source and means of transmission
• how they cause damage and how the body reacts