L6: Infectious Disease

Question 1

organism which is gram variable

Answer 1

Gardnerella vaginosis

Question 2

KOH prep shows

Answer 2

fungi

elastin

Question 3

Tzank prep stain

Answer 3

Giemsa stain
-or-
Wright stain

Question 4

To test for Herpes Virus

Answer 4

Tzank prep: multinucleated cells

Immunofluorescence more commonly used

Question 5

India ink looks for

Answer 5

cryptococcus

Question 6

Gram (-) spirochetes can be seen with

Answer 6

direct visualization

too thin to be cultered or gram stained

Question 7

Gram (-) spirochetes

Answer 7

Syphilis

T pallium

Question 8

How to test for syphilis (2)

Answer 8

1. Venereal disease Research Laboratory (VDRL):
   a. CSF test
   b. Fluorescent treponemal antibody absorption test (FTA-ABS)
2. Rapid Plasma Reagin: Serum test for syphilis

Question 9

Latex agglutination assay tests for

Answer 9

Pathogen specific antibodies/antigens

Meningococcal capsular antigen in CSF

Question 10

Enzyme-linked immunoassay (ELISA) test for

Answer 10

antibodies

Question 11

How long does it take for an immune response to develop and antibodies to appear

Answer 11

2 weeks

Question 12

Indirect immunofluorescence assay (IFA) tests for

Answer 12

antibodies, ANA antibody

Question 13

Nucleic Acid Amplification (NAAT)/Polymerase Chain Reaction (PCR) test for

Answer 13

Bacterial/viral DNA or RNA, faster than ELISA

Question 14

Acid fast bacilli test for

Answer 14

TB (less sensitive)

Question 15

Acid fast bacilli sample

Answer 15

sputum smear

Question 16

Elisa sample

Answer 16

Serum

Question 17

most sensitive and specific TB test

Answer 17

Mycobacterial culture

Question 18

in who is a PPD test falsely negative

Answer 18

immunocompromised

Question 19

For people with patient contact, PPD is done

Answer 19

Twice, repeat in 8-10 weeks

Question 20

Fluids generally considered to be sterile

Answer 20

CSF, pleural, pericardial, peritoneal, synovial fluids

Question 21

Is clean catch urine sterile

Answer 21

no

Question 22

Broth (tube) microdilution method pros

Answer 22

MIC

Question 23

Broth (tube) microdilution method cons

Answer 23

high cost, miniature size of dilution analyses less bacteria

Question 24

Agar dilution test

Answer 24

Multiple plates and multiple samples on a single set of plates

Question 25

Agar dilution test is reserved for

Answer 25

reserved for resistant species or ones that require special growth conditions, (expensive and labor intensive) DOES provide MICs

Question 26

Disk diffusion test (Kirby-Bauer method)

Answer 26

Agar plate with filter paper disks containing fixed concentration of abx→ measure growth inhibition zones

Question 27

Disk diffusion test aka

Answer 27

Kirby-Bauer method

Question 28

Does the disk diffusion test give you an MIC?

Answer 28

NO. Tells: Susceptible, intermediate, or resistant as measured by growth inhibition zones

Question 29

Antimicrobial gradient method

Answer 29

Agar+plastic strips imbedded with a graded concentration of antimicrobial→ growth inhibition along strip is measured

Question 30

Does the antimicrobial gradient method tell MIC?

Answer 30

Yes | by identifying intersection of growth inhibition with gradient

Question 31

How to collect blood for blood cultures

Answer 31

2 specimens from 2 different sites (NOT IV) collected before starting abx (notify lab if abx started)

Question 32

Blood cultures are used to diagnose/treat

Answer 32

``` Bacteremia 1 (+) + 1 (-) → contamination 2 (+) → (+) Prelim report: 24 hours ID organism: 24-72 hours ```

Question 33

When should a blood culture be repeated within 48 hours of beginning antibiotics?

Answer 33

``` IF: S aureus Known/suspected endocarditis Persistent leukocytosis Prosthetic valvular grafts Cardiac pacemakers Abx-resistant pathogens Unknown source, Infection site with limited abx penetration (abscess, joint space, CNS, abdomen) ```

Question 34

Mesothelial cells

Answer 34

thick layer of connective tissue lining body cavities and organs

Question 35

line body cavities

Answer 35

Parietal membranes

Question 36

surround organs

Answer 36

Visceral membranes

Question 37

Accumulation of fluid in a body cavity due to filtration of blood serum across a physiologically intact wall

Answer 37

transudative effusion

Question 38

Accumulation of fluid within a body cavity due to inflammation and vascular wall damage

Answer 38

exudative effusion

Question 39

Transudative effusion is caused by

Answer 39

Systemic disease→ pressure differences | CHF, hepatic cirrhosis, nephrotic syndrome

Question 40

Exudative effusion is caused by

Answer 40

Malignancy, infection, inflammatory disorder, trauma

Question 41

Lab testing of effusions

Answer 41

Transudative: no further Exudative: further testing to rule out cause, compare fluid to serum