Infectious Agents

Question 1

virus membrane/ cell wall

Answer 1

protein capsid

some have host cell envelope

Question 2

bacteria membrane/ cell wall

Answer 2

G + thick peptidoglycan

Sterols: mycolic acids in crynebacteria, mycobacteria and nocardia; cholesterol in terponemes & borrelia

Question 3

Fungi membrane/ cell wall

Answer 3

ergesterol

chitin

Question 4

What is obligate intracellular?

Answer 4

all viruses

bacteria: clamydia, rickettsia, coxiella, erlichiae, anaplasma and some mycobacteria (M. leprae)

Question 5

What is the domain of fungi and parasites?

Answer 5

eukaryotes

Question 6

Prions

Answer 6

PrP sc converts to PrP c proteins

Version: Kuru, Creutzfeld-Jakob disease, Bovine spongioform encephalopathy (can end up as a variant of CJD), Scrapie (goats scraping themselves)

Question 7

Normal flora found where?

Answer 7

skin, nasopharynx, oral cavity, vagina, colon

Question 8

Routes of microbial infection

Answer 8

skin, gi tract, respiratory tract, urogenital tract

Question 9

B cell defects –>

Answer 9

bacteria (specially encapsulated), giardia and some viruses

Question 10

deficiency of C1, 2 or 4

Answer 10

Encapsulated bacteria (S. penumo)

Question 11

deficiency of C3

Answer 11

encapsulated bacteria

Question 12

deficiency of C5,6,7,8 or 9

Answer 12

Neisseria (gonococcus and meningococcus)

Question 13

deficiency of neutrophil function

Answer 13

S. aureus, gram neg. bacteria, fungi

Question 14

deficiency of toll-like receptor signaling

Answer 14

susceptible to S. pneumo, viruses

Question 15

T cell defects

Answer 15

bacteria, viruses, fungi, parasites

Question 16

phagocytosis defect or splenectomy / sickle cell anemia susceptible to?

Answer 16

susceptible to encapsulated bacteria

Question 17

splenectomy patients need vaccinated against

Answer 17

encapsulated bacteria!

pneumococcal, etc.

Question 18

example of suppurative (purulent) infection

Answer 18

staphylococcal pneumonia

Question 19

Examples of mononuclear and granulomatous inflammation

Answer 19

syphilis (mononuclear cell infiltrates)

tuberculosis (formation of granulomata)

Question 20

Example of cytopathic-cytoproliferative reaction

Answer 20

herpes virus

Question 21

Example of tissue necrosis pathogen

Answer 21

clostridium perfringens

Question 22

example of chronic inflammation/ scarring

Answer 22

chronic hepatitis (cirrhosis)

Question 23

example of something that elicits no immune reaction

Answer 23

mucormycosis in bone marrow transplant patients

Question 24

Rapid Testing in Microbiology- direct microscopy

Answer 24

Gram for bacteria and fungi
H&E and Papanicolaou stains for viral changes, fungi and bacteria
Auromine-rhodamine immunofluorescence for mycobacteria and cryptosporidium
Calcofluor white stain for fungi
Acid fast stain for mycobacteria
Silver stains for fungi, spirochetes, pneumocystis
PAS stain for fungi
Mucicarmine stain or India ink for cryptococcus capsule
Giemsa stain for parasites and campylobacter

Question 25

rapid testing in microbiology: antigen/ antibody detection

Answer 25

``` Enzyme immunoassays (EIAs) – giardia, cryptosporidium, Direct fluorescent antibody and latex agglutination – bordetella, legionella, pneumocystis, treponema, group A or B streptococci ```

Question 26

rapid testing-- molecular detection

Answer 26

Nucleic acid probes and nucleic acid amplification – chlamydia, gonococcus, tuberculosis, CNS infections (herpes, Epstein-Barr, varizella zoster, cytomegalovirus, enterovirus, parechovirus)

Question 27

rapid testing- serology

Answer 27

Bacteria (helicobacter, bordetella, borrelia, pneumococcus, treponema), viruses (Epstein-Barr, hepatitis viruses, CMV, HIV, etc.), fungi (blastomyces, histoplasma, coccidioides, etc), parasites (toxoplasma, girardia, babesia, etc.)

Question 28

minimum inhibitory concentration

Answer 28

The lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation Key words: *** after overnight ***

Question 29

Catalase (+)

Answer 29

staphylococci | S. aureus, e.g.

Question 30

Catalase (-)

Answer 30

streptococcus (and enterococcus) | S. epidermides, e.g.

Question 31

Hemolysis

Answer 31

``` used for streptococci Blood agar plate alpha = partial (green) beta = total gamma = no hemolysis ```

Question 32

Fermenter

Answer 32

Lac (+) E. Coli, Enterobacter and Klebsiella

Question 33

Sabouraud dextrose

Answer 33

culture for fungi