Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PID > diagnostics > Flashcards

diagnostics Flashcards

1
Q

importance of clinical diagnostics

A

guide care of patients, determine appropriate treatment of infections, determine the risk of spread of infectious organisms to other patients, public, or clinic workers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

specimen types

A 
blood
tissues
scraps/swabs/ impressions
transudate/exudate
urine/misc fluids
feces
vomitus/sputum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

guidelines for collecting specimens

A
  1. use aseptic technique– no contamination
  2. collect samples specific for flora (avoid environmental/ normal flora contamination)
  3. specimens should be taken before antibiotics/treatments are started and during acute phase of disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

acute phase

A

-symptoms are very pronounced, typically a strong reaction of immune system and active replication/multiplication of pathogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

most common specimens for bacterial infections– dogs

A 
skin (dermatitis, pyoderma) 
ear
urine
wounds
blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

most common specimens for bacterial infections– horses

A

nasal

wound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

most common specimens for bacterial infections– cats

A

wounds
urine
ear
skin (dermatitis, pyoderma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

most common specimens for bacterial infections– dairy cows

A

milk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

most common specimens for bacterial infection– food producing animals

A

post mortem tissue/organ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

collection technique– dog pyoderma

A

LIMITS CONTAMINATION FROM NORMAL FLORA

remove fluid specimen from intact pustule & avoid contamination from bacteria on healthy skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

collection technique– cystocentesis

A

LIMITS CONTAMINATION FROM NORMAL FLORA

remove urine directly from bladder with sterile syringe
-avoids contamination from lower urinary tract– cystocentesis is preferred specimen for UTI diagnostics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

specimens for detection of parasite infections

A
  • feces
  • vomit
  • sputum
  • blood
  • muscle biopsy
  • skin scraping
  • urine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

common specimens for viral infections

A 
swabs: nasal/tracheal/sputum/eye
feces
blood 
specimen type depends upon suspected viral infection and patient symptoms
also from tissue and organs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

consequences of incorrect specimen collection and mishandling

A

incorrect/unsuccessful diagnosis due to specimen contamination/degradation/ inappropriate collection, infection of other patients/the public/ workers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

handling of specimens

A

specimens should be handled in regard to their temp requirements, oxygen requirements, and also stored to preserve them, timing may be a key factor in the specimen’s survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

diagnostic tests– phenotypic methods

A
  • microscopic examination (view under a microscope)

- culture/biochemical tests: grow and isolate pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

diagnostic tests– immunological and serological methods

A
  • serological test blood specimen

- immunological- based diagnostics: binding of specific antibodies or antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

molecular diagnostics

A

identification of markers in genome or proteome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

parasite diagnosis by phenotypic tests

A

-direct examination from blood smear, skin scraping, other specimens can visualize +/- stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

concentration techniques

A
  1. filtration or centrifugation methods
  2. flotation/sedimentation techniques from feces, vomit, sputum
  3. Baermann test for larval identification
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

success of parasite diagnosis by phenotypic techniques depends upon several factors

A
  1. stage of infection (life-cycle stage of parasite), parasite type/sex, amount of parasite egg shedding
  2. animal age and species
  3. specific technique procedure
  4. severity of infection/parasite type (amount of egg production varies)

there are many FALSE NEGATIVES and sometimes FALSE POSITIVES, repeat tests

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

cytology– use microscopes for:

A
  • cell morphology
  • bacteria (+/-) morphology
  • parasite (+/-) morphology
  • can’t see viruses
  • simple stain- 1 dye used- may not stain all components/ cells
  • differential stain- more than one dye used, multistep, can distinguish between different types of cells and structures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

advantages of cytology

A
  • determine cell/tissue morphology
  • cellular association of bacteria/parasites/fungi
  • morphology (shape of bacteria, fungi, parasites)
  • provides impression of disease stage/severity
  • immediate analysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

disadvantages of cytology

A
  • mild/chronic infection may not be readily detected

- not all samples are appropriate for cytology of bacterial infections (i.e. fecal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

H & E stain

A
  • common tissue stain used for wide range of normal and abnormal cells and tissues
  • different structures= different affinities for dyes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Romanowsky stain (Wright’s/ Giesma/ Diff-Quick)

A
  • used to sample abnormalities (traditionally blood), bacterial and parasite infections
  • Diff quick= fast and can stain multiple specimen types
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Gram stain

A

-differentiates between Gram +/ Gram - bacteria

28
Q

to culture or to not culture… that is the question

A
  • type of infection: bacterial/fungal, virus/parasite are not cultured
  • time (typically 2-10 days for result)
  • expensive
  • can be unidentifiable
29
Q

environmental requirements bacteria

A
  • temp: common range 20-42 C
  • pH: acidophiles (<7), neutrophiles (7), alkaliphiles (>7)
  • atmospheric composition- O2 and CO2
30
Q

nutritional differences bacteria

A
  • require carbon and nitrogen- differences in rqmt
  • require nitrogen, phosphate, sulfate, potassium, magnesium, calcium, iron
  • trace elements, purines/pyrimidines and vitamins
31
Q

agar (solid)

A
  • nutrient media- general growth
  • selective media- growth of suspected pathogen type
  • differential media- most are selective media and helpful in bacterial id
32
Q

broth (liquid)

A
  • nutrient broth

- enrichment broth- increase number of a specific bacterial type, inhibit growth of others

33
Q

biochemical testing

A
  • enzymes
  • fermentation

helpful in pathogen ID

34
Q

non-selective media

A
  • basic nutrient media: TSA, LB agar, MH agar

- enriched nutrient media: blood agar, brain heart infusion agar, chocolate agar, lysed blood agar

35
Q

fastidious bacteria

A

require specific nutrients and culture conditions

36
Q

oxygen requirements

A
  • anaerobic bacteria require growth in the absence of oxygen
  • capnophiles require growth with carbon dioxide
37
Q

selective medias

A
  • for gram +: Phenylethyl alcohol agar
  • for fungi- SabDex agar (low pH)
  • for gram - :eosin methylene blue agar
  • antibiotics in agar- resistant organisms will grow
38
Q

differential media

A
  • blood agar- not selective
  • MacConkey Agar- gram -, lactose fermentation
  • Mannitol salt agar- gram +, mannitol fermentation
  • CLED agar- urinary bacteriology, lactose fermentation
39
Q

enzyme production

A
  • catalase: breaks down hydrogen peroxide
  • coagulase: causes fibrin in blood to clot
  • urease: hydrolyses urea
  • indole: converts tryptophan into indole
  • different bacteria produce different enzymes– used for species id
40
Q

ID test strips/plates

A
  • economizes space, time, and raw materials
  • usually generates a unique code of results for identification
  • remel rapID, sensititre ID plates, BD crystal
41
Q

urine paddles: UTI culture paddles

A
  • provides semi-quantitative colony count
  • presumptive ID of many common pathogens
  • paddle has two sides:
    • one is EMB media for gram- neg bacteria
    • one is non selective CLED media
  • incubate at 37 C for 18-24 hrs for id
42
Q

immunochemical tests

A
  • detect pathogen- specific antibodies or antigens
  • antigen is molecule that triggers host immune response
  • antigens from pathogens can be
    • the whole pathogen itself (only a small part on the surface is actually the antigen)
    • molecule produced by pathogen
    • pathogen molecules presented on surface of host cells
  • immunochemical tests exploit principles of pathogen-specific immune response to detect and ID pathogens
43
Q

Common specimens for antibodies

A

IgG: blood (common), tissue fluids
IgM: blood (common antibodies detected)

44
Q

specimens for anigens

A

-primarily area of infection where pathogen replicates or antigen is present

45
Q

indicators of active/recent infection

A
  1. pathogen detection (phenotypic methods or antigen)
  2. present or recent clinical symptoms of infection
  3. amount or titer of antibodies- number of antibodies circulating will decrease with time

because pathogen-specific antibodies can be detected in absence of infection may need additional diagnostics – may need to retest

46
Q

ELISA (enzyme- linked immunosorbent assay)

A
  • specific antigen or antibody detection
  • detects immune response to virus, parasites, bacteria or fungi
  • immune system makes unique antibodies for each pathogen encountered
  • high sensitivity and specificity
  • quantitative: amount of antigen or antibody present
47
Q

basic ELISA assay steps

A

-standard plate set up
-either:
A. add serum from patient, if antibodies bind to that antigen, antibody will not be washed away
B. add specimen from patient, if antigens bind to antibodies: antigen will not be washed away

48
Q

immunological based diagnostics- lateral flow immuniochromatographic assay (variation of ELISA)

A
  • analyte flows by capillary action
  • antigen binds to conjugate antibody
  • conjugate antibody- antigen complex= captured by antigen specific antibodies, if antibodies bind it is positive for antibodies
  • second control line for conjugate antibodies
49
Q

IDEXX snap tests

A
  • variation of lateral-flow immunochromatopgraphic assay
  • detection of antigen or antibody from specimens
  • works with conjugate and antibody complex
  • conjugate contains enzyme that interacts with substrate molecules to give color on snap test for positive result
  • can measure several infectious disease in one snap test
50
Q

immunofluorescence and immunohistochemistry

A
  • direct or indirect (uses second antibody)
  • specimen: tissue or cell smear
    1. primary antibody specific to antigen, binds to antigen
    2. secondary antibody is specific to Fc portion of primary antibody, binds to primary antibody
    3. secondary antibody is immunoflorescent– multiple secondary antibodies can bind to primary antibody, which amplifies the signal
51
Q

immunological-based diagnostics

A
  • specific antigen or antibody detection: detects immune response to virus, parasites, bacteria
  • agglutinations: particles clump together (antibody and its antigen interaction)
  • indirect (most common): antigen or antibody coated on beads
52
Q

advantages of immunochemical tests

A
  • ID pathogen when pathogen cannot be cultured
  • most have high sensitivity
  • most have high specificity
  • mid to high-volume testing possible
53
Q

disadvantages of immunochemical tests

A
  • detection of antibody may not indicate active infection (titer)
  • antibody detection from specimen: very early in infection may not be detected (can re-test)
  • possible that antibodies may detect more than one pathogen
54
Q

molecular diagnostics for infectious disease

A
  • techniques or tests that determine pathogen ID by characteristic genetic or protein material
  • uses pathogen-specific genetic sequences to ID pathogen
  • can use pathogen-specific protein profile to ID pathogen
55
Q

MALDI-TOF: bacterial identification

A
  • type of mass spectrometry
  • detects parts of pathogen (mostly ribosomal peptides by their mass and charge)
  • each pathogen has signature pattern of fragments
  • software analyzes pattern- matches pattern to its database
  • takes bacterial or fungal “fingerprint”
56
Q

advantages- MALDI-TOF

A

rapid ID, high throughput, can ID bacteria and fungi

57
Q

disadvantages- MALDI-TOF

A
  • isolated pathogen analysis
  • ID is limited to reference spectra in database
  • high initial cost
58
Q

multiplex PCR

A
  • detection of nucleic acid from multiple virus, bacteria, fungi, parasite species in single sample
  • either PCR based or uses tagged oligonucleotide probes in digested sample
59
Q

real-time PCR

A
  • pathogen-specific sequence amplification of nucleic acid and measurement
  • can be individual or multiplex
  • quantitative for pathogen
  • used highly for virus ID and amount of virus in specimen (quantitative)
60
Q

advantages: Molecular diagnostics

A
  • faster than culture based methods
  • nucleic acid-based techniques are highly sensitive and can detect low level of pathogen
  • accurate
  • high volume testing possible
61
Q

disadvantages: molecular diagnostics

A
  • expensive: initial investment for equipment
  • expensive reagents
  • more specialized personnel to run machines
  • yes/no answers
  • possible false negatives/positives
62
Q

on site analysis

A
  • cytology

- point of care tests: urine paddles, parasite direct ID, IDEXX SNAP tests

63
Q

diagnostic lab

A
  • specimen culture
  • antimicrobial susceptibility testing
  • molecular testing and advanced immunochemical testing
64
Q

good diagnostic lab…

A
  1. provides guidance for optimal specimen management (tells you how to get it to them)
  2. performs immunochemical and molecular methods for ID and antimicrobial susceptibility testing
  3. implements transparent and continuous quality assurance methods
  4. is accredited by national reference laboratories
  5. has availability of skilled microbiologists, parasitologists, and virologists for case-based expert advice and data interpretation
65
Q

some potential reasons for no diagnosis

A

1incorrect sample collection/handling (contamination) or pathogen not present in sample

  1. incorrect/inappropriate diagnostic test for pathogen/stage of infection
  2. can be bad timing
    - may need to reassess patient

PID (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions