Serological test Flashcards
Skin test used for diagnosing Trichinosis.
Trichinosis Bachman Intradermal Test.
Skin test used for diagnosing Tuberculosis.
Tuberculin Skin Test (TST).
Name of the tuberculin skin test associated with von Pirquet’s method.
Von Pirquet’s Test.
Skin test used for diagnosing Brucellosis.
Brucellergin skin test.
Skin test used for diagnosing Coccidiomycosis.
Coccidiodin skin test.
Test used for diagnosing Lymphogranuloma venereum.
Frei Test.
Skin test used for diagnosing Histoplasmosis.
Histoplasmin skin test.
Test used for diagnosing Diphtheria.
Schick test.
Test used for diagnosing Scarlet fever.
Dick test.
Test used for diagnosing Glanders.
Mullein test.
Skin test used for diagnosing Toxoplasmosis.
Toxoplasmin skin test.
Different from Sabin Feldman as it uses blood
Test used for diagnosing Anthrax.
Ascoli test.
Test used for diagnosing Ascariasis.
Moan test.
Skin test used for diagnosing Hydatid disease.
Casoni Intradermal Test.
Skin test used for diagnosing Streptococcus pneumoniae infection.
Francis skin test.
Test used for diagnosing Leishmania infection.
Montenegro Test.
Test used for diagnosing Toxoplasmosis.
using blood
Sabin Feldman Test.
Test used for diagnosing Schistosoma infection, detects antibody.
Circumoval Precipitin Test.
Test used for diagnosing Trichinella infection through xenodiagnosis.
Beck’s Test.
Bacterial infection caused by Group A streptococcal infection with beta-hemolysis and pus production
S. pyogenes
Protein in Group A Streptococcus that inhibits phagocytosis and complements activation
M protein.
Test to measure antibodies in response to S. pyogenes infection
ASO Titration.
Test for Group A streptococcal infection estimating the amount to inhibit hemolysis of rabbit red blood cells
ASO Titration (Macrotechnique of Rantz and Randall).
Streptococcal virulence factor that dissolves clots
Streptokinase.
Enzyme in Group A Streptococcus acting as a spreading factor
Hyaluronidase.
Toxin in Group A Streptococcus that causes subsurface hemolysis
Streptolysin O (SLO).
Reagent used in ASO Titration to test for neutralization of SLO
5% rabbit RBC suspension.
Principle of ASO Titration test involving the reaction of Streptolysin O (SLO) with the patient’s antibodies
Neutralization reaction - The reduced form of SLO is neutralized by ASO in the patient’s serum.
Endpoint indicating a positive result in ASO Titration test
(+) No hemolysis.
Unit used to express ASO titer based on the reciprocal of serum volume needed to neutralize SLO
International units (recommended), Todd units
Normal ASO Titer for children (in Todd units)
<125 Todd units.
Normal ASO Titer for adults (in Todd units)
<166 Todd units.
Indication of moderately elevated ASO titer in adults
> 240 Todd units.
Indication of moderately elevated ASO titer in children
> 320 Todd units.
Clinical manifestations of Streptococcus pyogenes infection
Upper respiratory tract infection (Pharyngitis)
Skin infections (Erysipelas, Impetigo, Cellulitis)
Streptococcus Toxic Shock Syndrome
Otitis media
Puerperal sepsis
Sinusitis
Septic arthritis
Acute bacterial endocarditis
Meningitis.
Scarlet fever manifestation associated with Streptococcus pyogenes infection
Strawberry-colored tongue.
Complications of Streptococcus pyogenes infection
Acute Rheumatic Fever (molecular mimicry)
Post-streptococcal glomerulonephritis (characterized by RBC casts).
Laboratory diagnosis of Streptococcus pyogenes infection (screening test)
Culture - Susceptibility to bacitracin.
Confirmatory test for Streptococcus pyogenes infection
PYR test (L-pyrolidonyl-B-napthylamide activity).
Method for detecting Group A Streptococcal antigens
Lateral flow immunochromatographic assay.
Important antibodies for diagnosing Streptococcus pyogenes infection complications
Antistreptolysin O, Anti-DNase B, Anti-NADase, Anti-hyaluronidase.
Significant titer rise for diagnosing recent Streptococcus pyogenes infection
A four-fold rise in titer in acute and convalescent phase sera.
Recommendation for antibody testing in Streptococcus pyogenes infections
Use at least two tests for antibodies to different exotoxins.
Components detected in Streptozyme testing
Anti-streptolysin O (ASO), Anti-hyaluronidase (AHase), Anti-streptokinase (ASKase), Anti-nicotinamide-adenine dinucleotide (anti-NAD), Anti-DNase B antibodies.
False positive result in Streptozyme testing
Prone to false positive results.
Principle of Rapid Latex Agglutination Test
Passive agglutination - SLO (soluble toxin) is attached to latex carrier to detect antibody.
Positive result in Rapid Latex Agglutination Test
Agglutination ≥ 200 units per mL.
Negative result in Rapid Latex Agglutination Test
Agglutination < 200 units per mL.
Principle of ASO Titer Test
Automated procedure measuring ASO titers via Nephelometry.
Measurement and reporting of ASO Titer Test
Reported in international units based on light scatter of immune complexes.
Principle of Anti-DNase B Testing
Neutralization.
Use of Anti-DNase B Testing
Highly specific for group A streptococcal sequelae.
Agent responsible for Gastric and Duodenal ulcers and Gastric Carcinoma
Helicobacter pylori.
Virulence factors of Helicobacter pylori
CagA (dysfunction of cell signal transduction pathway) and VacA (codes for toxin precursor).
Helicobacter pylori’s survival factors in the gastric environment
Spiral shape, flagella, urease, and flagellar sheath.
Invasive diagnostic methods for Helicobacter pylori
Endoscopy and biopsy.
Noninvasive diagnostic methods for Helicobacter pylori
Urea breath testing, enzyme or lateral flow immunoassays, molecular tests for H. pylori DNA.
Primary screening method for Helicobacter pylori infection
Serological test for detection of IgG, IgM, and IgA antibodies.
Leading cause of upper respiratory infections worldwide
Mycoplasma pneumoniae (atypical pneumonia)
Condition associated with high titer of cold agglutinin (IgM) causing intravascular agglutination when exposed to cold
Cold agglutinin syndrome (CAS).
Cold agglutinin syndrome (CAS) in Mycoplasma pneumoniae infection
Abnormal cold IgM antibodies with Anti-I specificity.
Cold agglutinin syndrome (CAS) in Infectious Mononucleosis
Cold autoantibody with Anti-i specificity.
Primary method for diagnosing Mycoplasma pneumoniae infection
Culture in Trypticase soy broth, SP4 medium, or viral transport medium (requires freezing at -70°C).
Antibodies detected for current infection of Mycoplasma pneumoniae
M pneumoniae-specific IgM.
Antibodies detected for past infection of Mycoplasma pneumoniae
M pneumoniae-specific IgG.
Gold standard for diagnosing Mycoplasma infections
Molecular diagnosis.
Principle of rapid screening test for cold agglutinins
Hemagglutination.
Antigen used in rapid screening test for cold agglutinins
Fresh human group O cell (Anti-H) to prevent ABO antibody cross-reaction.
Procedure for cold agglutinin testing
Incubate at 4ºC for 18-24 hours, heat to 37ºC for 30 minutes to check for agglutination changes.
Positive result in cold agglutinin screening test
No hemagglutination at 37ºC, hemagglutination at 4ºC.
Negative result in cold agglutinin screening test
No hemagglutination at 37ºC or 4ºC.
Significant titer for cold agglutinin syndrome
32-64.
Weil Felix Test Principle
Direct Agglutination.
Why is the Weil Felix Test nonspecific?
Because of cross-reaction with Proteus antigen.
Significant titer for Weil Felix test
> 160 (strongly suggestive of infection).
Which antigens are used in the Weil Felix Test?
P.vulgaris: OX-19, OX-2; P.mirabilis: OX-K.
Scrub typhus result in Weil Felix test
OX-19 (-) OX-2(-), OX-K (4+).
RMSF (Rocky Mountain Spotted Fever) result in Weil Felix test
OX-19 (++++) OX-2(+), OX-K (-).
Q Fever & Rickettsial Pox result in Weil Felix test
OX-19 (-) OX-2(-), OX-K (-).
Preferred method for diagnosing Rickettsial infections
Serodiagnosis.
Question
Answer
Agent of Typhoid Fever
Salmonella enterica subspecies enterica serotype typhi.
How is Typhoid Fever acquired?
Ingestion.
TSI reaction for Salmonella typhi
K/A, (-) gas, (+) H2S.
IMViC reaction for Salmonella typhi
-+–.
Antigens of Salmonella species
O (somatic), H (flagellar), K (capsular).
Who was Typhoid Mary?
Mary Mallon, a famous carrier of Salmonella typhi.
Purpose of the Kauffmann-White Classification
Classifies the genus Salmonella into serotypes.
Example of a Salmonella serotype in Kauffmann-White Classification
Salmonella enterica serotype Typhimurium 1,4,5,12:i:1,2.
Specimens for Salmonella Identification - 1st week of infection
Blood.
Specimens for Salmonella Identification - 2nd week of infection
Stool.
Specimens for Salmonella Identification - 3rd week of infection
Urine.
Principle of Widal Test
Direct agglutination.
Significant titer in Widal test
80 and above.
Typhidot test purpose
Detection of specific IgM and IgG to Salmonella typhi.
Interpretation of O in Widal test tube test
Typhoid fever.
Interpretation of O and H in Widal test tube test
Typhoid fever.
Interpretation of H in Widal test tube test
Past infection, Convalescence (Recovery), Exposure, and Recent infection.
Interpretation of O, H, and PARA A in Widal test tube test
Typhoid and Paratyphoid fever (Mixed infection).
Interpretation of PARA A, B, and C in Widal test tube test
Paratyphoid fever.
Characteristics of Spirochetes
Slender, flexuous, helically shaped, unicellular; periplasmic flagella (endoflagella); gram-negative, microaerophilic bacteria; corkscrew flexion or motility.
Cause of Syphilis
T. pallidum subspecies pallidum - also known as the great pox, Spanish disease, the great imitator.
Cause of Yaws
T. pallidum subspecies pertenue.
Cause of Bejel (Nonvenereal Syphilis)
T. pallidum subspecies endemicum.
Cause of Pinta
T. carateum.
Cause of Syphilis
T. pallidum subspecies pallidum.
Syphilis Transmission Modes
Sexual transmission, parenteral exposure, congenital infections during pregnancy, least blood transfusion (due to labile nature in cold after 3 days).
Origin of the Name ‘Syphilis’
From a poem written in 1530 describing a mythical shepherd, Syphilus, who was punished for cursing the gods.
Primary Syphilis Features
Appearance of hard chancre; painless, solitary lesion with raised, well-defined borders; lasts 1-6 weeks.
Laboratory Test for Primary Syphilis
Direct detection from the chancre using dark field microscopy.
Secondary Syphilis Features
Occurs 1-2 months after primary chancre disappears; generalized lymphadenopathy, fever, rash, and condylomata lata (flat wart-like lesions).
Laboratory Tests for Secondary Syphilis
Dark field microscopy, serologic tests for specific and nonspecific antibody production.
Latent Syphilis Features
Noninfectious, no clinical symptoms, positive serologic test; early latent within 1 year, late latent after 1 year.
Tertiary Syphilis Features
Occurs 10-30 years after secondary stage; includes gummatous syphilis, cardiovascular disease, and neurosyphilis.
Neurosyphilis Clinical Manifestation
Asymptomatic CNS involvement, detected by CSF examination.
Congenital Syphilis Cause
Maternal spirochetemia and transplacental transmission of T. pallidum.
Hutchinsonian Triad
Hutchinson’s teeth, interstitial keratitis, nerve deafness.
Saddle-Nose Deformity in Tertiary Syphilis
Perforation of the palate and collapse of nasal bones.
Fluorescent Antibody Testing for Syphilis
Direct IF using fluorescent-labeled antibody conjugate to detect T. pallidum.
Reagin Antibodies in Syphilis
Non-specific antibodies detected in serologic tests.
Anti-Treponemal Antibodies in Syphilis
Specific antibodies directed against T. pallidum.
Wasserman Test
Complement fixation test detecting reagin antibodies in syphilis.
Cardiolipin in Wasserman Test
Antigen from beef heart extract used in Wasserman test.
Positive Wasserman Test
No hemolysis in complement fixation indicates positive result.
VDRL Test Principle
Flocculation reaction detecting reagin antibodies.
VDRL Serum Preparation
Heated serum (56°C for 30 mins)
VDRL Reagents
Cardiolipin (main reagent), lecithin (neutralizes anticomplementary properties), cholesterol (increases reacting surface of cardiolipin).
VDRL Rotator Settings
180 rpm for 4 mins (serum), 180 rpm for 8 mins (CSF).
VDRL Ring Diameter
14 mm for serum, 16 mm for CSF; depth 1.75 mm.
VDRL Antigen Delivery Needle for qualitative serum
Gauge 18; 60 drops/mL
VDRL Antigen Delivery Needle for quantitative serum
Gauge 19; 75 drops/mL
VDRL Antigen Delivery Needle for saline
Gauge 23; 100 drops/mL
VDRL Antigen Delivery Needle for CSF
Gauge 21/22; 100 drops/mL
VDRL Reporting Results: No clumps
Non-reactive
VDRL Reporting Results: Small clumps
Weakly reactive
VDRL Reporting Results: Medium to large clumps
Reactive
RPR Reagents
Cardiolipin, lecithin, charcoal, choline chloride (serum inactivator), thimerosal (preservative)
VDRL False Positives
SLE, RA, infectious mononucleosis, malaria, pregnancy.
RPR Test Principle
Flocculation reaction detecting reagin antibodies; macroscopically read.
RPR Serum Preparation
Unheated serum used.
RPR Ring Diameter
18 mm for antigen suspension.
RPR Antigen Delivery Needle
Gauge 20 (Hamilton syringe needle, 60 drops/mL).
Treponemal Serologic Tests detection
Treponemal antibodies with treponemal antigens
FTA ABS Principle
Indirect Fluorescent Immunoassay, used with Dark Field Microscopy
FTA ABS Reagent
Nichol’s strain fixed on a slide
FTA ABS Absorbent
Reiter Treponemes capture patient antibodies
Treponemal Antigens
Reiter strain (non-pathogenic), Nichol’s strain (pathogenic)
HATTS Principle
Hemagglutination test
HATTS Reagent
Turkey RBCs with treponemal antigen
MHA-TP Principle
Hemagglutination test
MHA-TP Reagent
Sheep RBCs with treponemal antigen
TPI Principle most specific for syphilis
Antibody-complement mix immobilizes T. pallidum
TPI Reagent
Live T. pallidum from infected rabbits
TPI Positive Result
> = 50% immobilization of T. pallidum
Borrelia Characteristics
Arthropod-borne, less tightly coiled than leptospires, easily stained, visualized with Giemsa staining under bright field microscope
Lyme Disease Causative Agent
Borrelia burgdorferi senu lato complex
Lyme Disease Transmission
Ixodes spp ticks; coinfection with Babesia spp possible
Lyme Disease Reservoir
White-footed mouse
Lyme Disease Stages
Localized rash (Erythema chronicum migrans), early dissemination, late disseminated with arthritic symptoms
Lyme Disease Rash
Bull’s eye rash
Lyme Disease Serological Test - Western Blot (IgM)
Reactivity for two of the following bands: 24, 39, 41 kDa
Lyme Disease Serological Test - Western Blot (IgG)
Reactivity for five of the following bands: 18, 28, 39, 45, 66, 21, 30, 41, 58, 93 kDa
Leptospira Characteristics
Spirals with hooks at one or both ends, can be impregnated with silver
Leptospirosis Causative Agent
Leptospira interrogans
Leptospirosis Infection Stages
Septicemic stage (fever, headache), Immunological stage (jaundice)
Leptospirosis Culture Medium
Fletcher semisolid, Stuart liquid, or EMJH semisolid medium
Leptospirosis Laboratory Diagnosis
Culture, microscopy, serological test
