Exam 4 Study Guide Flashcards
Recent (Acute) infection is indicated by the presence of which Antibody
IgM
When should a convalescent titer be drawn
10-14 days after the acute specimen
IgM negative; IgG positive indicates what
past exposure to an organism
How much increase should there be between acute/convalescent titer to be considered diagnostic
a fourfold increase
Cause of ‘Atypical’ or ‘Walking pneumonia’
mycoplasma pneumoniae is the cause of walking pneumoniae
Why is walking pneumoniae termed atypical
because it cannot be treated with penicillin
Leading cause of community acquired pneumonia
mycoplasma pneumoniae, leading cause of respiratory infections worldwide
These cause RBC to agglutinate at 4ﹾC; reversible at 37ﹾC
cold agglutinins (cold antibodies)
Possible cause of False-Negatives in Cold Agglutinin test
It is only present in 50% of patients with Mycoplasma pneumoniae, even if someone has the infection, they may not produce cold agglutinins
If the test is not done or appropriately stored at cold temperatures
Anti-streptolysin O titer (ASO titer) may be run to indicate which 2 sequelae infections
acute rheumatic fever and poststreptococcal glomerulonephritis
ASO titer test is a hemolysis inhibition test (no hemolysis is a positive) measured in ____
TODD units
Rocky Mountain Spotted Fever (RMSF) is caused by what bacteria? Transmitted by what
Rickettsia rickettsii, transmitted by ticks
Name 3 Spirochete Diseases
borrelia burgdorferi=lyme disease
treponema pallidum= syphilis
leptospira=leptospirosis
Causative agent of Lyme Disease. Transmitted by what? What is the hallmark clinical sign
borrelia burgdoderi
transmitted ixodes (deer ticks)
Target rash
Spirochete that causes Leptospirosis? Where do humans get exposed
caused by Leptospira, humans are mucous membrane contact with urine-contaminated water
Causative agent of syphilis
treponema pallidum
Stage of syphilis when rash on palms and soles of feet appear
secondary stage (1-2 months)
stage of syphilis that is asymptomatic
latent stage
stage of syphilis when chancre appears
primary stage
stage of syphilis when neurosyphilis is diagnosed
tertiary stage
stage of syphilis where patient is not
infectious except pregnant women
latent stage
Drug used to treat syphilis
penicillin
What are you looking for in Direct Syphilis Detection methods
Demonstration of spirochetes in active lesions
darkfield microscopy- fluid from a lesion is examined for characteristic corkscrew morphology and flexing motility
fluorescent antibody- highly specific and sensitive; conjugate to T. pallidum
Name 2 Non-treponemal tests
VDRL (venereal disease research laboratory test)
RPR (Rapid Plasma Reagin test)
What are the similarities between the 2 non-treponemal tests
both detect reagin antibodies, IgG or IgM, against cardiolipin
both use cardiolipin-lecithin-cholesterol
Both are screening tests
Both can use false positives
Both look for clumping (flocculation)
Both are performed at room temperature 23 C
What are the differences between the 2 non-treponemal tests
VDRL- is heated to 56 C for 30 min
RPR- no heating is required
VDRL-mixed with cardiolipin-lecithin-cholesterol suspension
RPR- mixed with charcoal particles
VDRL- rotated for 4 min at 180 rpm
RPR- rotated for 8 min at 100 rpm
VDRL-microscopic flocculation
RPR- macroscopic flocculation
VDRL- less sensitive in primary stages
RPR- more sensitive in primary stages
What is the name of Antigen complex used in Non-treponemal tests
cardiolipin, lecithin, and cholesterol
What is the name of the Antibody being tested for in Non-treponemal tests?
reagin (igG or IgM)
Testing of patients in the secondary stage of syphilis can result in a false negative due to what?
What do you perform because of this
due to the prozone, perform a two-fold serial dilution
What are some causes of false-positives in non-treponemal tests
malaria, SLE, RA, hepatitis, pneumonia, aging, and infectious mononucleosis
What are treponemal tests -testing for? Name 2 treponemal tests
FTA-ABS (florescent treponemal absorption)
TP-PA (T. Pallidum particle agglutination)
What is the most sensitive test for syphilis in any stage
FTA-ABS (fluorescent treponemal absorption)
What test is used for CSF or Congenital testing for syphilis
Nontreponemal test
What test is a screening for syphilis done on donor blood? What sample do you start with? If
positive, then what next
A Nontreponemal test like RPR or VDRL, you start with serum, if positive preform a treponemal test
Which type of syphilis test is sensitive but not specific for syphilis
Non-treponemal test like RPR & VDRL
Which type of syphilis tests are used to monitor effective treatment
non-treponemal antibody titer
Define parenteral transmission
body fluids (blood, semen, etc)
Define perinatal transmission
when a mother with HIV passes the virus to her infant during pregnancy, labor and delivery, or breastfeeding (through breast milk)
Hepatitis is an inflammation of the
liver; nonspecific indicators include hepatomegaly, liver
tenderness, jaundice, dark urine, light colored feces & elevated bilirubin and liver enzymes.
Two Hepatitis infections transmitted by fecal-oral route
HAV & HEV
Three Hepatitis infections transmitted perinatally and parenterally
HBV, HCV & HDV
HAV is found where
in overcrowding, poor & homeless population
HDV is always found as a
coinfection of HBV
HBsAG
Hepatitis B surface antigen; first antigen to be detected after infection; signals an acute or active infection; Screen blood donors for this antigen; antigen used to make vaccine
HBeAG
Hepatitis Be antigen; second antigen to be detected indicates infectivity
(transmissibility) and still acute infection
Anti-HBc
antibody to HB core antigen; first antibody to be detected; IgM level indicates current or recent infection(used when HBsAG is undetectable); Total anti-HBc mainly IgG
Anti-HBe
antibody to HBe antigen; second antibody to be detected; indicates recovery of HBV infection
Anti-HBs
antibody to HB surface antigen; third antibody to be detected; indicates recovery to past infection & IMMUNITY. If only Anti-HBs is found this indicates immunity due to vaccine
Any initial positive results for HBV should be
verified by retesting and confirmed with molecular testing
Chronic HBV state
anti-HBc is only antibody testing positive
These never develop immunity, continue to carry the virus and are still infectious
Chronic Carriers
HBIG
Hepatitis B immune globulin given to employee after accidental needle sticks
oral infections; cold sores, fever-blisters
Herpes simplex virus 1 (HSV-1
genital infections; Sexually transmitted disease (STD)
Herpes simplex virus 2 (HSV-2)
infectious mononucleosis (IM); MonoSpot – tests for heterophil
antibodies; Symptoms of IM: fever, lymphadenopathy, sore throat, fatigue
Epstein-Barr Virus (EBV
Define heterophil antibody
reacts with antigens from two or more species; found in 40-80% of IM patients
Monospot & Paul-Bunnell test
most important in organ transplantation failure; GVHD; can only give CMV negative blood to infants transfusions
Cytomegalovirus (CMV)
Varicella-Zoster virus (VZV)
the cause of varicella (chickenpox) and herpes zoster (shingles)
cause of german measles; MMRV vaccine; can cause birth defects & miscarriages from infected mothers
Rubella virus
cause of measles; MMRV vaccine
Rubeola virus
Define Attenuated vaccine
live heat inactivated pathogens (usually a virus)
Not able to produce disease
Able to produce a strong immune response forming antibodies
ex: influenza, chicken pox, measles, polio, and TB
common clinical manifestation is parotitis (swollen glands in neck); MMRV vaccine
Mumps virus
Immunization for measles, mumps, rubella, and varicella
MMRV
responsible for adult T-cell leukemia and lymphomas
Human T-cell Lymphotropic Virus (HTLV-1/2)
warts; may cause cancer; asymptomatic; mostly a STD
Human Papillomavirus (HPV)
Define Retrovirus
RNA converts to DNA inside infected cell
is a Retrovirus; HIV-1 targets CD4 lymphocytes;
screening test ELISAs for HIV-1 antibody; Western Blot assay is confirmatory test and HIV NAT
(nucleic acid test)
Normal healthy adult ratio- T helper CD4 : T-cytotoxic (suppressor)CD8 is 2:1
HIV patient ratio of CD4: CD8 is 1:2 or 1:1
Transmission of virus: Perinatal, Intimate sexual contact, contact with blood & blood products
Human Immunodeficiency Virus (HIV)
caused mostly by the HIV-1 virus
AIDS (acquired immunodeficiency syndrome)
3 Phases (Stages) of HIV
Primary (Phase 1) = >50%flu-like symptoms (IM-like symptoms) with decrease CD4
Latency (Phase 2) = asymptomatic increase in CD4;
AIDS Phase 3 = immunosuppression; opportunistic infections; decrease CD4
Flow Cytometry is used
in testing and monitoring CD4 counts
Decreased CD4 cell population is hallmark feature of
HIV infection
profound immunosuppression with life-threatening opportunistic infections and malignancies such as pneumocystis, Kaposi sarcoma, candidiasis, etc.
AIDS infection
recommended for HIV infected persons to delay disease; not
cure for AIDS
Antiretroviral therapy (ART)
Newer serological testing for HIV involve testing for
p24 Ag and HIV RNA
CD4 T-cell enumeration by immunophenotyping using Flow cytometry is
gold standard for
monitoring HIV disease; CD4 T-cell count <200/uL indicates AIDS (stage 3 HIV)
Define viral load
amount of HIV RNA is in a patient’s plasma; reflects the natural history of HIV infection; detectable 11 days after infection; physicians watch the patient’s viral load to predict disease progression
