7) IFA Flashcards
1
Q
main purposes of serological testing
A
- monitor course of infection
- detect past infection
- assess immune status
2
Q
IgM in a newborn indicates…
A
congenital infection
(not mom’s)
3
Q
molecular assays for viral nucleic acids are especially valuable for infections of the…
A
CNS
small amts of organism
4
Q
IFA uses —— to detect ———
A
fluorochrome-labelled conjugate
Ab in pt serum
5
Q
most common fluorochrome
A
FITC
6
Q
direct IFA
A
pt tissue on slide + conjugate Ab + fluorochrome
7
Q
indirect IFA
A
substrate with Ag on slide + pt serum (Ab) + conjugate + fluorochrome
8
Q
IFA is (more/less) sensitive than EIA
A
less
9
Q
disadvantages of IFA
A
- background fluorescence
- nonspecific binding to substances in serum
- fluorochromes sensitive to pH, light
- reading must be done frequently to maintain competency
10
Q
advantages of IFA
A
- fairly sensitive
- no hazardous materials
11
Q
fluorescent method developed to overcome IFA’s problems, but requires expensive instrumentation
A
fluorescent polarization immunoassay (FPIA)
12
Q
lamp in fluroescent microscope must emit…
A
proper wavelength to excite fluorochrome
13
Q
exciter filter in fluroescent scope
A
removes wavelengths other than one needed
14
Q
barrier/emission filter in fluorescent scope
A
screens out light other than that produced by fluorochrome
15
Q
complications associated with EBV
A
- Burkitt’s lymphoma
- nasopharyngeal carcinoma
- B-cell lymphomas
- chronic fatigue syndrome (not proven)
16
Q
EBV-EA indicates…
A
active infection
17
Q
EBV-M indicates…
A
acute infection
disappears after 3 months
18
Q
EBV-G indicates…
A
current or past infection
90% pop has it by adulthood
19
Q
EBNA detectable in….
A
convalescent stage of EBV
20
Q
rapid mono detects…
A
heterophile Ab
21
Q
produced by 40% EBV pts by week 1, and 90% by week 4
A
heterophile Ab
22
Q
heterophile Ab sensitivity low in…
A
children <12 yo
23
Q
negative heterophile Ab reflex
A
EBV-M serology
24
Q
autoAb that EBV can trigger
A
- cold agg
- RF
- ANA
25
most of pop exposed by elderly years, majority are asymptomatic or have mono-like illness
CMV
26
CMV life-threatening for...
newborns
immcomp
27
most common congenital viral infection
CMV
28
50% newborns with CMV develop...
sequelae (visual impairments, hearing loss, mental retardation)
29
immcomp patients especially vulnerable to CMV
aids
transplant
30
CMV in immcomp pts can affect...
eyes
liver
lungs
GI
CNS
31
identifies risk for disseminated CMV
CMV-DNA by PCR
32
method of choice for CMV serology
EIA
33
utility of CMV-G
documenting past infection in organ or blood donors
34
utility of CMV-M
limited
false negative and positives
35
primary infection occurs as gingivostomatotitis in children
HSV-1
36
retreats to nerve ganglia as dormant infection (can be fatal)
HSV-1
37
bilateral genital lesions with fever, lymphadenopathy, dysuria
HSV-2
38
utility of HSV-M
usually not tested for
39
utility of HSV-G
remains detectable throughout life
look for significant rise in titer
40
method of choice for detecting acute HSV infection
PCR for HSV nucleic acid
41
VZV transmission
- resp secretions or aerosols from skin lesions
- mother to fetus
42
VZV can cause congenital malformations in...
1st trimster
43
>95% of infections are in children
chickenpox
44
reactivation of chickenpox virus
zoster/shingles
45
utility of VZV-G
determine immune status of individual, especially pregnant women exposed during their pregnancy
46
given to pregnant women for passive immunity to VZV, but must be within ----- hrs of exposure
VZIG
96
47
most accurate & sensitive method for detecting VZV infection
can be performed on CSF
VZV-DNA by PCR
48
protozoan parasite that replicates inside macros
Toxoplasma gondii
49
T. gondii transmission
- ingestion of oocysts (contaminated soil, cat litter, undercooked beef or pork)
- transfusion/transplant
- mother to fetus
50
T. gondii complications
- can invade CNS and be lethal in immcomp
- death to fetus almost always in 1st tri
- hydrocephaly, blindness in 2nd tri
51
methods of choice for T. gondii serology
enzyme or chemiluminescent immunoassay
PCR method of choice for CSF, tissues
52
German measles
Rubella virus
53
mainly seen in young unvaxxed immigrants
rubella
54
can be subclinical or rash starting on face and spreading to extremities
rubella
55
Rubella effects on fetus
- miscarriage
- Rubella syndrome (deafness, eye defects, cardiac defects, mental retardation, motor disabilities)
56
method of choice for rubella Ab detection
ELISA
57
RUB-G utility
persists for life and indicates immunity if titer high enough
58
7 day measules
rubeola virus
59
Koplik's spots (red with gray in center) in mouth
maculopapular rash
Rubeola
60
rare complication of rubeola
SSPE - subacute sclerosing panencephalitis
fatal degenerative disease of CNS
61
effects of rubeola on fetus
- miscarriage
- preterm labor
- low birth weight
62
virus begins in nasopharynx and regional lymph nodes
moves to various tissue
mumps
63
complications of mumps
- meningitis
- deafness
- fetal death in 1st tri
64
protects babies up to 6 months or older from mumps
mother's Ab transferred through placenta
65
because of vaccines, assays to detect measles & mumps IgG are performed mainly...
to determine immune status
66
walking pneumonia
M. pneumoniae
67
leading cause of URT infection worldwide
M. pneumoniae
68
most widely used technique for M. pneumoniae
EIA
69
causes anti-I cold agglutinins
M. pneumoniae
(about 50% pts)
70
IgM can persist for considerable lengths of time, so not used to detect acute infection
L. pneumophila
71
bullseye rash in ----- of lyme patients
60-80%
72
complications of lyme
- dissemination to multiple organ systems
- chronic stage including arthritis
73
Lyme-G peaks...
6 months after onset, during arthritic sx
74
IFA for lyme uses ------- as substrate
spirochete
75
highly subjective and difficult to read, with beading fluorescence indicating false pos
IFA for lyme
76
recommendation to dx lyme
- screen with lyme-G by EIA
- confirm with western blot
77
gold standard for confirming rickettsial diseases
IFA
78
rickettsial organisms/diseases
- Bartonella quintana (bacillary angiomatosis)
- Bartonella henselae (bacillary angiomatosis, cat scratch fever)
- Coxiella burnetii (Q fever)
- Rickettsia rickettsii (RMSF)
- Rickettsia typhi (typhus)
- Ehrlichiosis
- Ehrlichia chaffeensis (HME)
- Anaplasma phagocytophilum (HGE)
79
recommended rickettsial antigens to test on sera are to rule in/out...
RMSF
typhus
HME
HGE
80
B. quintana transmission
louse feces
81
IgG ≥ 256 usually means recent infection
Bartonella
82
B. henselae transmission
- cat bites/scratches
- cat flea
83
Coxiella burnetii transmission
infected aerosols
84
2 antigenic variants are tested for (phase I and II of disease)
Q fever
C. burnetii
85
hallmark is maculopapular rash beginning on ankles and wrists
RMSF
86
RMSF transmission
ticks
87
typhus transmission
infected fleas' feces
88
can cause multilineage cytopenias
transmitted by ticks
Ehrlichiosis
89
HME
human monocytic ehrlichiosis
spotless RMSF
E. chaffeensis
90
HGE
human granulocyte ehrlichiosis
A. phagocytophilum
