Module 5.0

Question 1

Name some basic criteria of bacteria.

Answer 1

• Unicellular microscopic living organisms
• Most are harmless
• Contain DNA AND RNA
• Rigid cell wall
• Most grow in artificial media
• Sensitive to antimicrobial agents
• Replicate by binary fission

Question 2

List the basic structures of bacteria

Answer 2

Moving from out to in:
- Capsule
- Outer membrane
- Inner Membrane
- Flagella
- Pili, fimbriae
- Plasmid
- DNA
- Ribosomes

Question 3

Describe flagella and pili

Answer 3

• filamentous proteinaceous structures
• flagella are for motility
• Common pili: adherence to cell surface
• Sex pili: genetic exchanges

Question 4

Describe spores

Answer 4

• Most dormant form of bacteria
• Minimal metabolism and respiration
• Reduce Enzyme productivity

Question 5

Common ways to identify bacteria

Answer 5

• morphology
• staining
• cultural characteristics
• biochemical reactions
• molecular methods
• immunological methods

Question 6

What are the three basic bacteria shapes? (Morphology)

Answer 6

Sphere-shaped (cocci), rod-shaped (bacilli), spiral-shaped (spirochetes)

Question 7

Describe the staining differences for gram positive versus gram negative

Answer 7

gram-Positive = purple, gram-negative = red

Question 8

Do antibiotics react differently between GP and GN bacteria?

Answer 8

Yes, since the GP bacteria have a thick peptidoglycan layer and the GN have a high lipid layer the spectrum of antibiotics is not the same.

Question 9

What is a catalase test?

Answer 9

Used to differentiate bacteria that produce the enzyme catalase to breakdown hydrogen peroxide to oxygen and water. If it bubbles it is catalase positive.

Question 10

What is a coagulase test?-

Answer 10

Used to identify bacteria that produce the enzyme coagulase which converts fibrinogen to fibrin. If it forms a precipitate it is coagulase positive.

Question 11

What are some pros about using molecular methods for bacteria ID?

Answer 11

• most advanced and accurate method
• bacteria can be classified into sub-species, strains. serotypes or pathovar levels
• methods include: PCR, DNA/RNA probe tests, microarray, eletrophoresis, proteomics

Question 12

What is an obligate pathogen?

Answer 12

It must live inside a host to survive and reproduce

Question 13

What is a primary pathogen?

Answer 13

Can cause disease in a healthy host, in contrast to needing the host to be compromised to attack.

Question 14

What is an opportunist pathogen?

Answer 14

Can cause disease in a host with a weakened immune system when they let their guard down.

Question 15

What are fungi?

Answer 15

• Eukaryotes (bacteria and prokaryotes)
• Can float anywhere and contaminate any kind of samples
• vast majority are saprophytes (live on dead organisms
• reproduce by spores
• Chitin cell wall
• unicellular or multicelluar
• includes yeasts, molds, mushrooms

Question 16

List the 3 fungi types.

Answer 16

• yeast: single-celled, divide by budding, may have pseudohyphae
• molds: multicellular, grow by extension of asexual or sexual spore into tube-like structure (hypha), into cotton-wool mass (mycelium)
• dimorphic: have both yeast and mold like form

Question 17

What is the sequence of pathogenesis?

Answer 17

Enter/attach to the body, evasion of host defenses, multiplication and colonization, damage to host, transmission to other hosts (infectious)

Question 18

Which two types of pathogens are typically host specific?

Answer 18

Obligate and primary (essentially they need their host to survive and reproduce) whereas opportunists will take advantage of any opening

Question 19

What are some common ways bacteria cause host damage?

Answer 19

toxins, lytic enzymes, inflammation in response to microorganisms and their products, immune-mediated destruction

Question 20

LPS Endotoxin is a common virulence factor of which type of bacteria?

Answer 20

Gram negative, it can get through the lipid cell wall.