Clinical microbiology

Question 1

HAI?

Answer 1

Nosomical infection @ health care fascility

Question 2

Workflow?

Answer 2

Collect –> Culture –> Microscope –> Detection / Identification

Question 3

Reliability of a test?

Answer 3

Determined by the specificty and sensitivity

Question 4

Specificity?

Answer 4

Ability of a test to recognize a single pathogen

Question 5

Sensitivity?

Answer 5

Smallest quanta of a pathogen detected by a test

Question 6

Goal?

Answer 6

Low false-positive results

Question 7

General purpose media?

Answer 7

Blood or chocolate agar

Question 8

Selective media?

Answer 8

Specific for some organisms. Inhibatory agents that reduces growth for some

Question 9

Differential media?

Answer 9

Allow identification of organisms based on the appearance after growth.

Question 10

Blood?

Answer 10

General purpose media - incubate in anoxic and oxid conditions for growth - flourescense / turbidity or O2 or CO2 levels –> Stain –> Selective media - > identification

Question 11

CSF?

Answer 11

Should be blank and high turbidity usually means high levels of leukocytes. Stain -> incubated with selective media.

Question 12

UTI’s?

Answer 12

Blood agar and selective/differential media to difference between gram- lactose fermenters from non-fermenters. Including a low growth for gram+ bacteria.

> 10^5 cells / ml

Question 13

Fecal?

Answer 13

Low pH -> sterile container -> transport and inoculated to suitable media

Question 14

Wounds?

Answer 14

Syringe/biopsy -> Stain

Question 15

STI’s?

Answer 15

Stain

Question 16

Detect Anaerobic pathogens?

Answer 16

For obligate anaerobes. A media with high [] of reducing agent for the reduction of oxygen, and a redox indicator for anoxic conditions.

Question 17

Skin test?

Answer 17

Th1 cells with DTH respons and a + tuberculine test

Question 18

mABS?

Answer 18

Monoclonical antibodies produced by a B-cell clone in the area of diagnostic and therapeautic purposes.

Question 19

Serology?

Answer 19

Study of antigen and antibody reactions in vitro.

Question 20

Precipation?

Answer 20

Soluble antigen and antibody forms a insoluble complex

Question 21

Agglutination?

Answer 21

Reaction between antibody and particlebound antigen that forms clumps of particles.

Question 22

Immunoflourensce?

Answer 22

Conjugated flourescent dyes that detect antigens or intact cells. Under the microscope.

Direct - Antibody + surface antigens coupled to the dye

Indirect - Antibody on cells surface, bind flourescent antibody to the non-flourescent antibody

Question 23

EIA?

Answer 23

Enzyme immuno assays 
D
I
S
C

Question 24

Direct?

Answer 24

Detects Antigen in blood and fecal sample

Antibody and dye binds to second antibody + enzyme and then addition of ES.

Question 25

Indirect?

Answer 25

Detects Antibody in body fluids

Antigen on supporting matrix and antibodies bind

Question 26

Antigen sandwich?

Answer 26

Detects Antibody in fluids. Immobilized and serum is added and binds to antigens.

Question 27

Combination?

Answer 27

Both.

Direct and sandwich in one matrix.

Question 28

Results EIA?

Answer 28

The coloured products is in proportion to the antigen bound by the E-S complex.

Question 29

Rapid tests?

Answer 29

Detects Antigens.

Results are absorbed to a fixed support material of paper or plastic .

Point of cause tests - color change in minutes

Antibodies to chromopore that diffuses through a matrix and antigens binds to the chromopore which becomes visible as a line of color.

Question 30

How does Western-Blotting work?

Answer 30

Antibody that binds to the conjugated enzyme. Coloured bands and after addition of the substrate on the strip @ site. + band matches.

Question 31

Requires?

Answer 31

S
T
I

Question 32

Separation?

Answer 32

Of the proteins on a polyacrylamide gel

Question 33

Transfer?

Answer 33

Or Blotting of the proteins from gel to a nitrocellulorse or nylon membrane.

Question 34

Identification?

Answer 34

Of proteins using a specific antibody

Question 35

Nucleic acid based clinical assays?

Answer 35

PCR-techniques with high sensitivity and employ primers for a pathogen specific gene to exam DNA from infected tissue.

Identify viruses and intracellular pathogens that can not be cultured or observed

Question 36

Nucleic acid hybridization?

Answer 36

Detects pathogens by probes that hybridize, which are labelled with a flourescent compound.

Lysing –> Denaturation NaOH –> Single strands –> Stable duplex

2 component probe –> Reporter and capture

Question 37

What is qPCR?

Answer 37

Quantitative real time PCR with flourescent probes that labels amplicons that allows target DNA to be visulaized by culturing flourescence.

No gel electrophoresis -> Based on the flourescence in PCR, determined by the amounbt of target DNA present in the ori sample.

Question 38

RT-PCR?

Answer 38

RNA –> cDNA via reverse transcriptase that detects RNA viruses.

Isolation of RNA sample –> cDNA amplified and employ qPCR –> particular gene from that pathogen.

Question 39

Qualitative PCR?

Answer 39

Labelled hybridization –> primers are added to a amplicon of a qPCR reaction.

Hybridization probes to the DNA Pol gene and the amplicon is detected by using 2 distinct hybridization probes with flourescent dyes.

Flourescence is measured and after the PCR cycle –> Melting curve analysis for nucleotide polymorphism.