Bacterial Diagnosis - Hunter

Question 1

T/F: a physician should begin treatment when an infectious disease is suspected BEFORE lab confirmation

Answer 1

yes

Question 2

What is the most common reason to fail to establish an etiologic diagnosis or a wrong diagnosis of an infectious organism?

Answer 2

Failure to properly collect a specimen

Question 3

In diagnosing a bacterial infection, what is the primary problem?

Answer 3

distinguishing normal flora from those causing infection

Question 4

What is a direct specimen?

Answer 4

microbes are in sterile site that can be accessed directly (e.g., needle aspiration of deep abscess, or blood collection)

Question 5

What is an indirect specimen?

Answer 5

microbes are in sterile site but must be collected through a non-sterile site (e.g., voided urine sample)

Question 6

What is a contaminated specimen?

Answer 6

Microbes are in site contaminated with normal flora (e.g., throat or stool culture)

Question 7

what two factors will dictate how the micro lab will approach isolating and identifying the bacteria?

Answer 7

the type of specimen you collected and your presumptive diagnosis

Question 8

T/F: transport of bacterial specimens is aerobic only

Answer 8

false, it can be either

Question 9

Microscopy
Broth and Agar Culture (antibiotic sensitivity testing)
Biochemical Characterization
Antibody Detection
Antigen Detection
Nucleic Acid-Based Tests

These are all methods of what?

Answer 9

identifying specific microbes in the lab

Question 10

What type of microscopy focuses directly on the specimen?

Answer 10

brightfield

Question 11

What type of microscopy has the central light blocked and peripeheral light is collected as scatter from the microbes?

Answer 11

darkfield

Question 12

What type of microscopy has microbes labeled with fluorescent dye that interacts at a certain wavelength?

Answer 12

fluorescence

Question 13

What type of microscopy is most common?

Answer 13

brightfield

Question 14

What power mag do you need to see bacteria?

Answer 14

100x under oil immersion

Question 15

What is the point of simple staining?

Answer 15

to just visualize bacteria

Question 16

what is the point of differential staining?

Answer 16

to distinguish different groups of bacteria, such as gram pos/neg

Question 17

what are special stains used for?

Answer 17

detect bacterial structures such as capsules, flagella, and endospores

Question 18

what are the two most common stains?

Answer 18

Gram stain and acid fast

Question 19

what medium is commonly used to grow bacteria?

Answer 19

agar

Question 20

T/F: a single microbes can grow to visible amounts

Answer 20

true

Question 21

T/F: almost all medically important microbes can be cultured

Answer 21

true

Question 22

How do you describe the colony form?

Answer 22

Circular
irregular
filamentous
rhizoid

Question 23

how do you describe colony elevation?

Answer 23

raised
convex
flat
umbonate
cateriform

Question 24

how do you describe colony margins

Answer 24

entire
undulate
filiform
curled
lobate

Question 25

What is the difference between nutrient, selective, and indicator media?

Answer 25

nutrient used to grow microbes, selective include antimicrobials to limit overgrowth of undesired bacteria, and indicator media has stuff that demonstrates specific activities of certain bacteria

Question 26

what type of media should you use if you have a sample of intestinal flora?

Answer 26

selective media to limit floral overgrowth to SELECT for you bacteria

Question 27

media that has a pH indicator of fermentation of sugars or RBC hemolysis is what type of media?

Answer 27

indicator media

Question 28

MacConkey agar is what type of media and is used to grow what?

Answer 28

Selective and indicator, gram negative, shows lactose fermentation

Question 29

Eosin Methylene blue agar is what type of media and is used to grow what?

Answer 29

Selective and indicator, gram negative, also shows lactose fermentation

Question 30

Hektoen Enteric agar is what type of media and is used to grow what?

Answer 30

Selective and indicator, SPECIFICALLY salmonella and Shigella, shows lactose fermentation and HYDROGEN SULFIDE production

Question 31

what does capnophilic mean?

Answer 31

bacteria grows in air but requires CO2

Question 32

Strictly (blank) bacteria die in the presence of air

Answer 32

anaerobic

Question 33

What are the factors that must be accounted for to grow bacteria? (3)

Answer 33

1. Broth/solid media 2. aerobic vs. anaerobic 3. CO2 levels

Question 34

What allows the selection of most effective chemotherapeutic agent against the bacterial isolate?

Answer 34

Antimicrobial sensitivity testing

Question 35

What is used to determine the minimum inhibitory concentration (MIC) of an abx?

Answer 35

broth dilutions and agar diffusion

Question 36

Bacitracin A disk is used to ID what bacteria?

Answer 36

Strep pyogenes

Question 37

Bile solubility allow for rapid differentiation of (blank) from other streptococci

Answer 37

pneumococci

Question 38

Catalase activity differentiates what two major groups?

Answer 38

staph (catalase pos) from strep and enterococci (catalase neg)

Question 39

Coagulase positive is KEY for what bacteria?

Answer 39

staph aureus

Question 40

Hippurate hydrolysis will ID group (blank) streptococci

Answer 40

group B

Question 41

An (blank) rapid test will detect E. coli in the urine

Answer 41

Indole A (hippurate hydrolysis)

Question 42

Optochin (P) disk can be used to ID what?

Answer 42

strep PNEUMONIAE; P for P

Question 43

Oxidase activity differentiates what type of rods?

Answer 43

gram negative rods from each other

Question 44

Enterobacteriaceae, Acinetobacter, and Stenotrophomonas are oxidase pos/neg?

Answer 44

oxidase negative

Question 45

Pseudomonas and Burkholderia are oxidase pos/neg?

Answer 45

oxidase positive

Question 46

S. pyogenes and Enterococcus can be determined via rapid test using what?

Answer 46

PYR hydrolysis

Question 47

What detection lab methods do you use to visualize sera Abs?

Answer 47

ELISA, westerns, or immunofluorescence

Question 48

The Ab response to some bacteria can take (days/weeks)?

Answer 48

weeks

Question 49

Serology is mostly useful in what type of studies?

Answer 49

epidemiologic

Question 50

T/F: Abs are a good detection mechanism of bacterial infection in immunocompromised patients?

Answer 50

FALSE

Question 51

Can Abs detect whole bacteria or bacterial toxins?

Answer 51

yes

Question 52

How does a non-amplified nucleic acid assay work?

Answer 52

hybridization of nucleic acids FROM pathogens TO labeled probes

Question 53

Are rapid non-amplified nucleic acid tests sensitive?

Answer 53

NO; but they are fast

Question 54

what is the amplifed NA test?

Answer 54

PCR

Question 55

IS PCR sensitive?

Answer 55

extremely

Question 56

T/F: the genomes of most bacterial pathogens are known

Answer 56

ture

Question 57

When would sensitivity not be an issue when IDing bacteria?

Answer 57

after the bacteria has bee grown up in vitro so you have a lot of it vs. trying to test in vivo