Rapid Testing in Immunology

Overview of Rapid Testing in Immunology

• This lecture covers different types of rapid testing conducted in the immunology lab.

Types of Tests in the Immunology Lab

• Wave Tests (CLIA Waived Tests)

  • Also known as simple tests.

  • Waived from certain federal requirements by CLIA (Clinical Laboratory Improvement Amendments).

  • Common examples include:

  • Glucose testing

  • Urine pregnancy screens

  • Rapid strep screens

  • Urine drug screens

  • Regulations:

  • Organizations performing waived testing must have a CLIA certificate.

  • Tests approved by the FDA for home use should not be used professionally except by patients themselves.

• Moderately Complex Tests

  • These are automated tests requiring some judgment and possible manual techniques.

• High Complexity Tests

  • More advanced and intricate testing processes.

Key Features of Waived Tests

• Criteria for definition by CLIA/ADA:

  • Tests are simple and accurate.

  • Minimal risk of erroneous results.

  • Likely accurate results; can be performed by almost anyone.

  • No reasonable risk of harm to patients.

• Testing Procedures:

  • Each waived test must have defined procedures and confirmatory testing if initial results are positive.

  • Example: A positive screening pregnancy test can be confirmed using a chemistry analyzer.

  • Regular maintenance and QC (Quality Control) checks are mandatory for instruments used in waived tests.

Competency Assessment for Staff

• Requirement for staff performing waived tests to demonstrate competency.

• Competency assessment methods include:

  • Performing tests on blind specimens to ensure accuracy (e.g., staff unaware of positive results).

  • Supervising staff during tests.

  • Documentation via sign-off sheets and performance logs.

  • Following QC performance standards.

  • Written testing assessments may also be included.

Point of Care Rapid Tests

• Non-instrument based testing referred to as Point of Care testing.

• Example: Malaria Testing

  • Microscopy is the gold standard for malaria diagnosis; rapid device testing (RDT) is an alternative.

  • RDT can screen for malaria using patient blood samples.

  • Confirm negative results with microscopy.

• Malaria Details:

  • Caused by parasites (specifically different species of Plasmodium):

  • Plasmodium falciparum

  • Plasmodium vivax

  • Plasmodium ovale

  • Plasmodium malariae

  • Example of blood smear microscopy for Plasmodium falciparum:

  • Microscopic examination identifies presence of malaria.

  • RDT process:

  • Patient sample is applied to test cartridge; results appear within minutes.

  • Negative results indicated by a single band at the control line.

  • In the case of Plasmodium vivax, a second band appears at the T2 lane. For Plasmodium falciparum, a band appears at the T1 lane.

  • Control line is always mandatory.

Rapid HIV Testing

• Similar to malaria testing in principle; uses a cartridge and operates similarly to urine pregnancy tests.

• Testing for antibodies rather than antigens.

• Sensitivity rates:

  • Typically high, about 99.9%.

  • Requires confirmatory testing for positive results.

• Variants of rapid HIV tests follow similar principles of looking for bands indicating positive results.

• Full range of rapid HIV test kits available, with sensitivity rates reaching up to 100%.

Pregnancy Testing

• Methodology similar to rapid HIV testing and malaria testing.

• Looks specifically for human chorionic gonadotropin (HCG) hormone:

  • Patient urine is applied to a test stick.

  • Depending on results, different indicators may show positive (e.g., a plus symbol) or negative results.

  • Importance of following the kit instructions for accurate interpretation of test results.

Conclusion

• Overview of the significance and methods of rapid testing in the immunology lab, highlighting the various tests available, their procedures, and essential qualities to ensure accuracy and reliability in testing results.