Podcast
Questions and Answers
What serological marker is indicative of an active hepatitis B infection?
What serological marker is indicative of an active hepatitis B infection?
Which serological marker indicates past exposure to the Hepatitis A virus?
Which serological marker indicates past exposure to the Hepatitis A virus?
What does the presence of IgM anti-HDV indicate?
What does the presence of IgM anti-HDV indicate?
Which of the following tests would be used to assess effective treatment for Hepatitis C?
Which of the following tests would be used to assess effective treatment for Hepatitis C?
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In which scenario would you expect to see Positive on total anti-HBc?
In which scenario would you expect to see Positive on total anti-HBc?
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What is the only way the Hepatitis D virus can be present?
What is the only way the Hepatitis D virus can be present?
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Which serological marker suggests immunity to Hepatitis B due to vaccination?
Which serological marker suggests immunity to Hepatitis B due to vaccination?
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Which category does Hepatitis C belong to?
Which category does Hepatitis C belong to?
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What is the primary mode of transmission for Hepatitis A virus?
What is the primary mode of transmission for Hepatitis A virus?
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Which serological marker indicates acute infection with Hepatitis A virus?
Which serological marker indicates acute infection with Hepatitis A virus?
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Which statement is true regarding Hepatitis E virus?
Which statement is true regarding Hepatitis E virus?
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Which of the following Hepatitis viruses is known to progress to a chronic state?
Which of the following Hepatitis viruses is known to progress to a chronic state?
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What does the total anti-HAV positive result indicate?
What does the total anti-HAV positive result indicate?
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Which of the following routes is NOT a mode of transmission for Hepatitis viruses?
Which of the following routes is NOT a mode of transmission for Hepatitis viruses?
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Which Hepatitis virus is part of the Hepeviridae family?
Which Hepatitis virus is part of the Hepeviridae family?
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What is the common characteristic of Hepatitis B, C, and D viruses regarding their transmission?
What is the common characteristic of Hepatitis B, C, and D viruses regarding their transmission?
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What is the predominant mode of transmission for Human Immunodeficiency Virus (HIV)?
What is the predominant mode of transmission for Human Immunodeficiency Virus (HIV)?
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What is the hallmark feature of HIV infection?
What is the hallmark feature of HIV infection?
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Which serological test is most reliable for detecting Varicella-Zoster Virus (VZV) antibodies?
Which serological test is most reliable for detecting Varicella-Zoster Virus (VZV) antibodies?
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During the Davidson Differential test, which antibodies are absorbed by guinea pig kidney cells?
During the Davidson Differential test, which antibodies are absorbed by guinea pig kidney cells?
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What type of antibodies are typically found in acute primary infection of Epstein-Barr Virus (EBV)?
What type of antibodies are typically found in acute primary infection of Epstein-Barr Virus (EBV)?
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Which of the following is a characteristic of the serological response in a convalescent or past infection of EBV?
Which of the following is a characteristic of the serological response in a convalescent or past infection of EBV?
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Which test is commonly automated and does not require viral culture for VZV antibodies detection?
Which test is commonly automated and does not require viral culture for VZV antibodies detection?
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What type of lymphocytes does HIV primarily infect?
What type of lymphocytes does HIV primarily infect?
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Which serological marker indicates an acute hepatitis E infection?
Which serological marker indicates an acute hepatitis E infection?
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What is the significance of detecting HBeAg in a patient with hepatitis B?
What is the significance of detecting HBeAg in a patient with hepatitis B?
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In what situation would a patient test positive for both HBsAg and total anti-HBc?
In what situation would a patient test positive for both HBsAg and total anti-HBc?
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What do IgG anti-HDV antibodies signify?
What do IgG anti-HDV antibodies signify?
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Which marker is used to determine the effectiveness of hepatitis C treatment?
Which marker is used to determine the effectiveness of hepatitis C treatment?
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Which virus is known to cause infectious mononucleosis?
Which virus is known to cause infectious mononucleosis?
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What is the primary method of transmission for the hepatitis C virus?
What is the primary method of transmission for the hepatitis C virus?
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Study Notes
Serological Diagnosis of Infectious Diseases
- Group A Streptococci (S. pyogenes) are a primary cause of bacterial pharyngitis and impetigo. Untreated infections can lead to complications like acute glomerulonephritis and rheumatic heart disease.
Lateral Flow Immunochromatographic Assays
- Strep A antigen from a throat swab reacts with enzyme-labeled antibodies on a membrane.
- Diagnostically important Streptococcal antibodies include Anti-streptolysin O (ASO), Anti-DNAse B, Anti-NADase, and Anti-hyaluronidase(AHase).
Streptozyme Test
- Detects diagnostically important streptococcal antibodies
- It's a slide agglutination screening test
- Sheep RBCs are coated with streptolysin, streptokinase, hyaluronidase, DNase, and NADase.
- A positive result shows hemagglutination.
Anti-streptolysin O (ASO) Testing
- ASO indicates recent streptococcal infection, potentially leading to acute rheumatic fever or poststreptococcal glomerulonephritis following a throat infection.
- The test measures the ability of antibodies in the patient's serum to neutralize the hemolytic activity of streptolysin O.
- Results are reported as a titer, which is the reciprocal of the highest dilution demonstrating no hemolysis.
- Titer can be reported in Todd units or International units.
- A titer of at least 240 Todd units for adults or 320 Todd units for children is considered moderately elevated.
Nephelometric Method
- Used for ASO testing (currently).
Anti-DNAse B Testing
- Helps diagnose glomerulonephritis preceded by streptococcal skin infections.
Helicobacter pylori Detection
- CLOtest detects urease activity in gastric mucosal biopsy.
- Positive result: hot pink gel; Negative: gel remains yellow.
- Serology is a primary screening method for H. pylori.
- Detects IgG, IgA, and IgM antibodies.
- Most tests for this organism detect IgG class.
- Techniques used involve ELISA, immunoblots, and LFA.
Mycoplasma pneumoniae Detection
- M. pneumoniae-specific antibody detection is possible with ELISA. IgM indicates recent infection.
- Cold agglutinins clump RBCs at 4°C. A titer of 1:64 or greater, combined with clinical presentation, suggests M. pneumoniae infection.
Rickettsial Infection Detection
- Indirect Immunofluorescent assay is the gold standard for serological diagnosis of Rocky Mountain Spotted Fever (due to R. rickettsii).
- The test uses to demonstrate a significant fourfold rise in antibody titers.
- Weil-Felix test detects Rickettsial antibodies, relying on cross-reactivity with polysaccharide antigens present on Proteus species. Relevant antigens are Proteus vulgaris: OX-19 and OX-2; Proteus mirabilis: OX-K. Different results indicate different types of rickettsial infections.
Syphilis Detection
- Caused by Treponema pallidum.
- Transmission routes include sexual, congenital, and parenteral (needles/blood).
- Serological tests can classify as non-treponemal or treponemal tests.
Non-treponemal Tests
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Detects reagin (antibody against cardiolipin). Cardiolipin, lecithin, and cholesterol are used in the test reaction
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Most common tests are the Venereal Disease Research Laboratory (VDRL) test and Rapid Plasma Reagin (RPR) test.
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VDRL and RPR are based on flocculation testing.
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VDRL test involves heating the serum at 56°C for 30 minutes to inactivate complement. Results are microscopically read. A positive VDRL result obtained from spinal fluis is indicative of neurosyphilis.
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A modified VDRL uses charcoal for macroscopic reading.
Treponemal Tests
- FTA-ABS uses Nichols strain of T. pallidum, and is a confirmatory test; specific and sensitive.
- TP-PA uses gel particles sensitized with T. pallidum; less sensitive than FTA-ABS
- It uses gel particles sensitized with T. pallidum sonicate.
Lyme Disease Detection
- Caused by Borrelia burgdorferi.
- Diagnosis is sometimes delayed because IgM antibodies are not detectable until 3-6 weeks after a tick bite and IgG antibody develops later.
- Screening tests include IFA or EIA.
- Confirmatory testing involves Western blot.
- IgM-positive if 2 or more bands are present (23, 39, 41). IgG-positive if 5 or more bands are present.
Fungal Serology (Candida species)
- Current recommendations for Candida species detection combine mannan and anti-mannan antibody detection in serum.
Cryptococcus neoformans Detection
- Cryptococcal polysaccharide antigen can be detected in serum and CSF using LA and enzyme immunoassays (EIA)
- False positives can be caused by rheumatoid factor, but can be reduced with heat and Pronase or 2-mercaptoethanol.
Aspergillus & Histoplasma Detection
- Aspergillus species detection uses galactomannan in serum via EIA, which increases the ability to diagnose invasive aspergillosis. An alternative is B-D-glucan.
- Histoplasma capsulatum uses Complement fixation (CF) and precipitation to detect antibodies. Precipitin band tests for H and M antigens.
Hepatitis Viruses (Hepatitis A, E, B, C, and D)
- Summaries of each hepatitis virus including mode of transmission, serological markers, and molecular testing methods are provided.
- Hepatitis A: Fecal-oral, IgM anti-HAV, HAV RNA via RT-PCR.
- Hepatitis E: Fecal-oral, IgM anti-HEV, IgG anti-HEV
- Hepatitis B: Parenteral, HBsAg, HBeAg, IgM anti-HBc, Total anti-HBc, etc
- Hepatitis C: Parenteral, Anti-HCV, and HCV RNA determination.
- Hepatitis D: Parenteral, co-infection with HBV, IgM anti-HDV, IgG anti-HDV, and HDV RNA detection.
Epstein-Barr Virus (EBV) Detection
- EBV causes infectious mononucleosis, and other disorders.
- Transmission is via intimate contact with salivary secretions.
- Hematology findings include lymphocytosis (>50% of total leukocytes) and at least 20% atypical lymphocytes.
- Serology involves detecting IM heterophile antibodies, which are IgM. These antibodies disappear usually within 3 months after symptom onset.
EBV-Specific Antibody Testing
- IgM anti-VCA, Anti-EA-D, IgG anti-VCA, Anti-EBNA and increased anti-EA can differentiate between acute primary infection, convalescent or past infection and reactivation.
Varicella-Zoster Virus (VZV)
- VZV causes varicella (chickenpox) and herpes zoster (shingles).
- FAMA (fluorescent Ab to membrane Ag) is the most sensitive and reliable serological test for antibodies.
- Reference method for antibodies. Live virus-infected cells are required.
- ELISA is a common method for VZV antibodies, does not require live virus infected cells.
Human Immunodeficiency Virus (HIV) Detection
- HIV belongs to the Retroviridae family.
- Transmission is via intimate sexual contact, blood exposure perinatally.
- Hallmark is a decline in CD4+ T cells.
- Testing includes detecting HIV antibodies, antigens, and nucleic acids.
- Screening includes ELISA, 4th generation automated Ag/Ab assays and rapid antibody tests. Confirmation includes Western blot HIV-1, 2 differentiation assays and PCR.
Additional Notes
- Specific tests and interpretations are listed in accompanying tables. These should be studied for details.
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Description
Explore the key concepts of serological diagnosis relating to infectious diseases, particularly focusing on Group A Streptococci. This quiz covers diagnostic tests such as Lateral Flow Immunochromatographic Assays, Streptozyme Test, and Anti-streptolysin O Testing. Find out about the implications of untreated infections and the associated complications.
