Microbiology

Question 1

Order these for increasing complexity.

Fungi, Virus, parasite, bacteria

Answer 1

Virus –> Bacteria –> Fungi –> Parasite

Question 2

What is a microbe?

Answer 2

A microscopic entity that can be unicellular, multi-cellular or acellular

Question 3

What kind of pathogens are viruses?

Answer 3

Obligate intracellular pathogens

Question 4

Virion

Answer 4

Single infectious unit, genome surrounded by protein capsid (and sometimes phospholipid membrane)

Question 5

How are viruses classified?

Answer 5

By their genome structure, virion morphology and replication strategy

Question 6

How are viral infections diagnosed?

Answer 6

By presentation and PCR

Question 7

What is an active viral infection?

Answer 7

Replicating virus is causing symptoms of disease

Question 8

Describe the possibilities of the viral genome.

Answer 8

Can be DNA, RNA, dsRNA

Question 9

What is a chronic viral infection?

Answer 9

Low levels of viral replication without clinical disease

Question 10

What is viral latency?

Answer 10

Virus is no longer causing disease but has not been eradicated and is dormant inside cells that are infected

Question 11

What is viral re-activation?

Answer 11

A change in the immune system (stress, immune suppression) results in replication of a dormant virus

Question 12

What is a prion?

Answer 12

Small infectious protein with no associated nucleic acid

Question 13

How do prions replicate?

Answer 13

Intracellular “spreading” of misfolded protein

Question 14

Why can these be difficult to treat?

Answer 14

They are often resistant to heat, chemicals and radiation

Question 15

Bacteria

• # cells?
• Prokaryote or eukarote?
• Internal organelles present?
• Structure of nucleic acid?
• Method of reproduction?

Answer 15

• Unicellular
• Prokaryotes
• No nucleus or membrane bound organelles
• DNA is compact and circular
• Binary fission

Question 16

The cell wall of bacetria may contain ______

Answer 16

Peptidoglycan

Question 17

What is a gram positive bacteria?

Answer 17

The gram stain turns peptidoglycan purple, so gram positive appear purple due to presence of peptidoglycan in their cell wall.

Question 18

What is gram negative bacteria?

Answer 18

They have a double plasma membrane with peptidoglycan between the 2 layers so the dye for gram stain cannot penetrate that membrane and stain peptidoglycan so they apper red on gram stain (no gram dye taken up)

Question 19

What are 2 kinds of bacteria that do not gram stain either + or -?

Answer 19

Mycobacteria

Mycoplasma

Question 20

How are bacteria classified?

Answer 20

Microscopic appearance

Growth

Metabolism

Genotype

Question 21

Fungi

Answer 21

Eukaryotes with cell walls composed of chitin and cell membranes with ergosterol

Question 22

What are the 2 basic forms of fungi growth?

Answer 22

Yeast (individual cells)

Mold (multicellular filaments)

Question 23

Fungi are common in air and on surfaces in our lives. Why aren’t we constantly sick from them?

Answer 23

They’re generally only invasive and lead to disease in immune deficient patients

Question 24

How are fungi classified?

Answer 24

Molecular biology

Growth (yeast, mold)

Patient presentation

Question 25

Parasite

Answer 25

Broad spectrum of eukaryotic organisms (unicellular - protozoa) (multicellular - helminths)

Question 26

Do all parasites cause disease?

Answer 26

No

Question 27

How are parasites transmitted?

Answer 27

Insects or fecal-oral route

Question 28

How is parasitic infection diagnosed?

Answer 28

Microscopic examination of blood smears or lesions

Question 29

Microbiota

Answer 29

Diverse population of microbes that inhabit the skin and mucous membranes in a mutualistic relationship

Question 30

What are important functions of the gut microbiota?

Answer 30

1) Metabolism and biosynthesis
2) Bacterial Interference
3) Immune maturation and homeostasis
4) Signaling to nervous system

Question 31

Microbiota

• Residents
• Transients
• Carrier state

Answer 31

• Strains that have established niche at site and occupy indefinitely
• Acquired from environment and established briefly but then eliminated via competition from residents or immune defense
• Organisms known to be potentially pathogenic but are residents or transients without pathogenesis in host

Question 32

Microbiota are ______ and can cause infection if they reach protected areas of body in sufficient number

Answer 32

Opportunists

Question 33

How do pathogens cause disease (generally)

Answer 33

Pathogen is able to invade host tissue to due trauma or when host resistance is impaired –> in tissue, they multiply and secrete disease causing agents –> abnormal conditions arise in host that interrupt normal body function due to pathogen

Question 34

Pathogenesis

Answer 34

Ability of oragnism to cause disease

Question 35

Virulence factors

Answer 35

Qualities enhance ability of microbe to cause disease

Question 36

What are the 3 means by which pathogens cause disease?

Answer 36

1) Invasion of host cell
2) Toxin production
3) Stimulate evading/immune response

Question 37

What is the epidemiologic triad?

Answer 37

Question 38

What is the chain of infection?

Answer 38

Question 39

What is the natural history of disease?

Answer 39

Question 40

What are contact precautions?

Answer 40

Clean hands, gown, gloves

Used to protect against tramission via indirect contact

Question 42

Droplet precautions

Answer 42

Clean hands, surgical mask, eye protection

Used to protect against infections transmitted via air droplets / particles

Question 43

Airbone precautions

Answer 43

Clean hands, N95 respirator, negative pressure room

Used to protect against microbes that stay in the air and travel

Question 44

Sterilization

Answer 44

Complete killing or removal of all living organisms from a particular location or material

Question 45

Disinfection

Answer 45

Destruction of mircobes by processes insufficient to be called sterile