3.1.2 Bacterial Pathogens

Question 1

Explain the significance of Koch’s postulates as they relate to bacterial pathogenesis

Answer 1

Question 2

What are some of the various types of virulence factors?

Answer 2

Motility, adhesins, invasins, exotoxins, endotoxins (LPS), degradative enzymes, caspsules, siderophores, resistance to antibiotics

Question 3

What is a virulence factor?

Answer 3

Help bacteria to invade the host, cause disease, and evade host defenses

Question 4

What are some different forms of adhesion virulence factors?

Answer 4

Pili (fibriae): Type I pili adhere to receptors containing mannose; P pili attach to receptors containing Gal-Gal

Protein adhesins

Biofilms (e.g. plaque)

Question 5

What are some of the different types of growth associated with invasion and spread?

Answer 5

Extacellularly

Intracellularly (obligate or facultative)

Question 6

Give three types of invasion of intracellular pathogens

Answer 6

Passive uptake, active invasion, transcytosis

Question 7

What is the difference b/t exotoxins and endotoxins?

Answer 7

Bacteria-mediated = exotoxins

Host-mediated pathogenesis = endotoxin (LPS, gram - only)

Question 8

Give four examples of exotoxins

Answer 8

Enzymes, A-B type toxins, membrane damaging toxins, superantigens

Question 9

What is the role of the different portions of A-B toxins?

Answer 9

B: Binds cell surface receptor

A: ezymatically active and is transported to the cell interior

Question 10

What are some of the targets of A subunits in A-B toxins?

Answer 10

Question 11

How do superantigens illicit a response?

Answer 11

Question 12

What type of toxin is LPS?

Answer 12

Endotoxin

Question 13

What are three methods to evade the host immune response?

Answer 13

Defensive, offensive, stealth

Question 14

What are some of the different sample collection methods?

Answer 14

Question 15

What are the different types of hemolysis seen in blood agar?

Answer 15

Question 16

What bacteria are associated with pigment formation?

Answer 16

Yellow: Staph aureus

Blue-green: Pseudomonas aeruginosa

Red: Serratia marcescens

Question 17

What are three different enzymatic tests that can be performed?

Answer 17

Catalase, coagulase, oxidase

Question 18

What type of microscopy is required to detect spirochetes?

Answer 18

Darkfield microscopy

Question 19

Describe staining techniques for microscopic examination of bacteria.

Answer 19

Gram stain: most common stain

Acid-fast stain (Ziehl-Neelsen): mycobacteria and other acid-fast microorganisms

Wright-Giemsa stain: chlamydial inclusion bodies, spriochetes, and Rickettsiae

Question 20

How is a gram stain performed?

Answer 20

Question 21

How is an acid-fast stain performed?

Answer 21

Question 22

What are some of the different serology diagnostic techniques?

Answer 22

Immunodiffusion

Latex agglutination

Enzyme-linked Immunosorbent Assay (ELISA)

Western immunoblot

Question 23

What is ELISA?

Answer 23

Question 24

How is Western immunoblot performed?

Answer 24

Question 25

Describe how antibiotic susceptibility testing is performed and interpreted.

Answer 25

Question 26

What is the dilution test for MIC?

Answer 26

MIC = minimal inhibitory concentration

Question 27

What are some molecular diagnostic techniques?

Answer 27

Question 28

What type blot is performed when nucleic acid probes target DNA? RNA?

Answer 28

DNA: Southern blot

RNA: Nothern blot

Question 29

What is the process of nucleic acid hybridization?

Answer 29

Question 30

What are the steps of PFGE?

Answer 30

Question 31

What some cutting edge molecular diagnostic techniques?

Answer 31

Mass spec, Next-gen sequencing

Question 32

What is quantitative diffusion E testing?

Answer 32