Microbial Classification

Question 1

What 4 classes of microorganisms are there?

Answer 1

• bacteria
• viruses
• fungi
• parasites

Question 2

what size are the following:

• smallest size seen by unaided human eye
• protozoa/fungi
• bacteria
• viruses

Answer 2

eye: 40 um

protozoa/fungi: 4-40 um

bacteria: 0.1-10 um
viruses: 0.03-0.3 um

Question 3

Describe the following:

• strict aerobes
• facultative anaerobes
• microaerophilic
• aerotolerant
• strict anaerobes

Answer 3

• strict aerobes: solely depend on aerobic respiration
• facultative anaerobes: can use either aeorobic or anaerobic metabolism
• microaerophilic: depends on aerobic respiration but killed by too much oxygen
• aertolerant: uses anaerobic fermentation but can survive in oxygen
• strict anaerobes: anaerobic metabolism, killed by oxygen

Question 4

List the aerobic gram + cocci we need to know:

Answer 4

• Staphylococcus spp.
• Streptococcus spp.
• Enterococcus spp.

Question 5

List the 2 aerobic and 1 anaerobic gram + bacilli we need to know:

Answer 5

O2:
Corynebacterium spp.
Bacillus spp.

AnO2:
Clostridium spp.

Question 6

List the 2 gram negative aerobic cocci we need to know:

Answer 6

• Neisseria spp.

- Haemophilus spp. (coccobacilli)

Question 7

List the 1 aerobic and 1 anaerobic gram negative bacilli we need to know:

Answer 7

O2:
-E. coli

AnO2:
Bacteroides spp.

Question 8

List 3 intracellular types of bacteria?

Answer 8

• Chlamydia spp.
• Chlamydophila spp.
• Rickettsia

Question 9

What bacterium lacks a rigid cell wall?

Answer 9

Mycoplasma spp.

Question 10

List 2 acid-fast/partially acid-fast bacteria:

Answer 10

• Mycobacterium spp.

- Nocardia spp.

Question 11

List 2 types of spirochetes:

Answer 11

• Treponema pallidum

- Leptospira spp.

Question 12

What are the classification criteria for viruses?

Answer 12

• DNA vs RNA
• single stranded vs. double stranded vs. segmented
• envelope/none
• shape of capsid: icosohedral (20 faces), helical, complex

Question 13

List the 2 DNA viruses you must know:

List the 5 RNA viruses you must know:

Answer 13

DNA:

• Hepatitis B
• Herpesvirus

RNA:

• Hepatitis A,C,E
• Influenza A, B
• HIV
• Rotavirus
• Norovirus

Question 14

What are the two major classes of fungi?

Answer 14

-filamentous fungi=moulds
(multi-cellular, hyphae collectively= mycelium)

-yeast (single cell, ovoid/sphere)

Question 15

What type of yeast must you know (you’ll see this a lot in practice):

Answer 15

Candida spp.

Question 16

What are the two classes of parasites?

Answer 16

• protozoa

- helminths

Question 17

What are the categories by which protozoa are divided?

Answer 17

• amoebae
• ciliates
• flagellates
• coccidia
• microsporidia
• sporozoa

*also divided by site of infx

Question 18

What are the categories of helminths?

Answer 18

• nematodes (round worms)
• cestodes (flat worms)
• trematodes (flukes)

*also divided by site of infx

Question 19

List the protozoa we need to know:

Answer 19

• Entamoeba histolytica (intestinal)
• Giardia lamblia (intestinal)
• Plasmodium spp. (blood)
• Toxoplasma gondii (other)
• Acanthamoeba spp. (other)

Question 20

List the helminths you must know:

Answer 20

• Ascaris lumbricoides (intestinal)
• Taenia spp. (intestinal)
• Schistosoma spp. (blood)
• Eichinococcus spp. (other)