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Block 6 Week 3 > Bacterial Diagnosis - Hunter > Flashcards

Bacterial Diagnosis - Hunter Flashcards

1
Q

how do you diagnose a bacterial disease?

A

exam patient
institute treatment for suspected disease
collect specimen
give to lab and tell them what you think it is
lab will give results
physician implements appropriate therapy

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2
Q

What is the most common reason for failing to establish an etiologic diagnosis?

A

failure of proper specimen collection

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3
Q

confirmation of the clinical diagnosis of a bacterial infection requires collection of an (blank)

A

appropriate specimen

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4
Q

For bacteria infections, the primary problem is in distinguishing what?

A

resident/normal flora microbes from those causing infection

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5
Q

What is a direct specimen?

A

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

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6
Q

What is an indirect specimen?

A

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

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7
Q

What is a contaminated specimen?

A

microbes that are in site contaminated with normal flora (i.e throat or stool culture)

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8
Q

T or F
The specimen and your presumptive diagnosis dictates how the clinical microbiology lab approaches the isolation and identification of the bacterial pathogen.

A

T

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9
Q

What is the most commonly used tool for specimen collection? What are its pitfalls?

A

sterile swab

only collects a small amount of sample and easily dries out

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10
Q

What is transport media for?

A

prevent drying out, maintain neutral pH and minimize growth of contaminants

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11
Q

Transport containers can be (blank) or (blank) depending on the particular microbe of interest.

A

aerobic

anaerobic

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12
Q

What are the ways to identify specific microbes in the clinical microbiology lab?

A 
microscopy
broth and agar culture (antibiotic sensitivity testing)
biochemical characterization
antibody detection
antigen detection
nucleic acid-based tests
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13
Q

What are the three microscopes used for direct examination of the specimen?

A

brightfield microscopy
darkfield micrscopy
fluorescence microscopy

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14
Q

What microscope is this:

light focused directly on specimen (most common)

A

brightfield microscopy

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15
Q

What microscope is this:

central light is blocked, peripheral light only collected as scatter from microbes

A

darkfield microscopy

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16
Q

What micrscope is this:
similar to darkfield, except microbes are labeled with dye that fluoresces when it interacts with light of an appropriate wavelength

A

fluorescence microscopy

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17
Q

Most bacteria are examined with a (blank) objection

A

100x oil immersion

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18
Q

What are the three kinds of stains for identifying bacteria?

A

simple stains
differential stains
special stains

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19
Q

What stain is this:

use a single dye to visualize bacteria

A

simple stains

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20
Q

What stain is this:

used to distinguish different bacterial groups (i.e gram positive vs. gram negative)

A

differential stains

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21
Q

What stain is this:
used to detect bacterial structures
(i.e capsules, flagella, and endospores)

A

special stains

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22
Q

What are the two most common bacterial stains?

A

gram stain and acid fast stain

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23
Q

Culture of microbes in (blank) or on (blank) medium is commonly used.

A

nutrient broth

agar

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24
Q

T or F

a single microbe can grow to amounts that are visible (i.e turbidity in broth or colonies on agar)

A

T

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25
Q

T or F

Almost all medically important microbes can be cultured

A

T

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26
Q

What are the four forms of bacteria colonies on agar?

A

circular, irregular, filamentous, rhizoid

27
Q

What are the five elevations of bacterial colonies on agar?

A

raised, convex, flat, umbonate, crateriform

28
Q

What are the five margins of bacterial colonies on agar?

A

entire, undulate, filiform, curled, lobate

29
Q

What is this:
made from animal or plant products supplemented with a variety of nutrients (grow many microbes, but there is no ‘universal’ culture medium

A

nutrient media

30
Q

What is this:
used when specific pathogens are sought in sites with an extensive microbial flora. Usually chemical additives or antimicrobials that inhibit unwanted microbial growth

A

selective media

31
Q

What is this:
contain substances designed to demonstrate biochemical or other features of specific pathogens (pH indicators of fermentation of specific sugars, or red blood cells that can be hemolyzed)

A

indicator media

32
Q

Cultures of most (blank) are maintained in an incubator at 35 to 37 degrees celcius.

A

aerobic

33
Q

Some aerobic bacteria are gorwn in air but require (blank)

A

CO2 (capnophilic)

34
Q

Strictly (blank) die in the presence of oxyygen. What do you need for these bacteria to grow?

A

anaerobic

specialized cultures

35
Q

What do you need to match to the microbes expected from the clinical examine and specimen collected?

A

Combos of broth, solid media, aerobic, CO2, anearobic incubation

36
Q

What does antimicrobial sensitivity testing allow for?

A

allows selection of most effective chemotherapeutic agent against the bacterial isolate

37
Q

How do you find the minimum inhibitory concentration of an antibiotic?

A

broth dilution tests and agar diffusion tests

38
Q

The (blank) method has been fully automated in the clinical microbiology lab.

A

broth dilution

39
Q

What do you use bacitracin (A) disk for?

A

for presumptive identification of strep pyogenes, which is sensitive to low concentration of bacitracin

40
Q

What do you use bile solubility for?

A

for rapid differentiation of pneumococci (which are bile soluble) from other streptococci

41
Q

What do you use catalase for?

A

an important characteristic that defines significant major groups of bacteria, (e.g. staphylococci {catalase positive} streptococci and enterococci {catalase negative}

42
Q

What do you use coagulase for?

A

for identification of staphylococcus aureus

43
Q

What do you use hippurate hydrolysis for?

A

a positive test is used for presumptive identification of group B strep. Indole A rapid test is used for presumptive identification of E. coli from urine specimens

44
Q

What do you use Optochin (P) disk for?

A

suscpetibility to optochin is presumptive identification of strep pneumonia

45
Q

What do you use oxidase for?

A

to help differentiate gram-negative rods

46
Q

What do you use PYR hydrolysis for?

A

A rapid test for presumptive identification of S. pyogenes and enterococcus

47
Q

How can you biochemically characterize pathogens?

A

via API20e System

48
Q

Antibodies formed in response to most bacterial infections can be detected by methods such as (blank X 3)

A

ELISA, western blot, immunofluorescense

49
Q

(blank) can indicate current, recent, or past infection

A

antibodies

50
Q

What the downside of using antibodies to detect pathogens?

A

some antibodies to some becateria take several weeks to respond.

51
Q

(blank) is quite useful in epidemiologic studies

A

serology

52
Q

(blank) can be unreliabe in immunocompromised patients.

A

antibody detection

53
Q

Whole bacteria, bacterial antigens, and bacterial toxins released into body fluids can be detected by (blank) using a variety of assays (e.g., immuno-fluorescence and ELISA)

A

antibodies

54
Q

T or F

rapid antigen detection systems have been developed (e.g. rapid strep test)

A

T

55
Q

What are the 2 types of assays in nucleic acid analysis?

A

non-amplified

amplified assays

56
Q

How does non-amplified nucleic acid analysis work?

A

they are based on hybridization of nucleic acids from pathogens to labeled probes.

57
Q

When do you want to use non-amplified assays?

A

to identify cultured bacteria where sensitivity is not as important

58
Q

PCR based tests are the (Bank) and are the most commonly used in the diagnostic laboratory

A

amplified assays

59
Q

When do you use PCR based test?

A

for sensitivity, they are extremely sensitive but subject to contamination. great care is needed to run good PCR tests

60
Q

(blank) probes can be used to identify bacteria in clinical specimens

A

nucleic acid

61
Q

The (blank) of most bacterial pathogens are known

A

genomes

62
Q

(blank) can be designed to hybridize with specific DNA sequences

A

Probes

63
Q

What assays are particularly useful when sensitivity is not an issue?

A

nucleic acid probes

Block 6 Week 3 (5 decks)

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