Deciphering TB Lab Reports Jessica Gentry Tuberculosis Laboratory Supervisor
Laboratory Regulation Laboratories performing diagnostic testing on human patient specimens are regulated by CLIA: Clinical Laboratory Improvement Amendments Regulations establish quality standards for laboratory testing performed on specimens from humans, such as blood, body fluid, and tissue, for the purpose of diagnosis, prevention or treatment of disease, or assessment of health. The purpose is to ensure high-quality testing.
Laboratory Regulation Examples of CLIA regulations: • Qualified, trained personnel performing testing • Laboratory inspections/audits • Enrolled in Proficiency Testing • Laboratory director overseeing testing • Written procedures for testing • Requirements for lab reports
Lab Reports Are Difficult to Read… • Different tests performed by different laboratories • PCR vs. probe vs. NAAT • Use of abbreviations • Inconsistent terminology • Multiple dates—collection date, test date, report date • Formatting • Results not listed in chronological order • Results from multiple laboratories on a single report • Results moved through a variety of LIMS systems
What’s on a Lab Report? • Laboratory Information • Patient Information • Specimen Information • Lab Testing Performed • Results Interpretation
Laboratory Information • Laboratory Name • Physical Address • Laboratory Medical Director • CLIA Certificate Number • Referral Laboratory Information • Department • Mycobacteriology • Tuberculosis • AFB Lab • Microbiology
Patient Information • Required: Two patient identifiers, typically: • Patient Name • Unique Patient Identifier (MRN) • Date of Birth • Optional: • Age • Gender • Race/Ethnicity • Address
Specimen Information • Specimen Source—sometimes listed as “site” • Pulmonary (Respiratory): Sputum, bronchial • Extrapulmonary: Urine, lymph node, CSF, tissue, etc. • Descriptive modifiers sometimes added—Induced or expectorated sputum, tissue location, RUL, etc. • Collection Date • Received Date • Accession Number/Specimen ID/Lab Number
Laboratory Tests • Test Performed • Test Result • Normal vs. Abnormal • Interpretation • Units of Measurement • Qualitative (QL) vs. Quantitative (QN) • Date Test Reported
AFB Smear Microscopy • Acid Fast Bacillus (AFB) • Acid Fast Bacilli, Acid Fast Bacteria • Digested, Concentrated, or Unconcentrated Smear • AFB Stain • Fluorescent • Fluorochrome • Auramine O-phenol
AFB Smear Microscopy AFB Negative • No Acid Fast Bacilli seen/observed on smear AFB Positive • Acid Fast Bacilli seen/observed/found on smear • <1/field, 1-10/field, >10/field, >50/field • 1+ (few), 2+, 3+, 4+ (many) • Rare, Few, Moderate, Many
Molecular Assays Assays that detect genetic material (DNA) of MTBC: • Polymerase Chain Reaction (PCR) • DNA Probe • MTB-RIF • Nucleic Acid Amplification Test (NAAT) • Negative, Not Detected • Positive, Detected • Testing can be in the specimen or culture • Assays can also look for other mycobacteria—M. avium complex, M. kansasii, M. gordonae
Molecular Detection of Drug Resistance Detection of mutations associated with drug resistance Assays • Pyrosequencing • Sanger Sequencing • Gene Xpert MTB/RIF • Whole Genome Sequencing (WGS) Results • Detected vs. Not Detected • Mutation Present vs. Mutation Absent Cepheid GeneXpert Cartridge
Culture Results • AFB culture is typically performed in tandem with an AFB smear • Test names: AFB Cx, AFB Cx + Stn, AFB Identification (ID) • Preliminary results may be reported at 2 wks, 4, wks, etc. • Culture negative—usually reported at 6 wks • Culture positive • Organism isolated, Organism ID • MTBC, MTB, Mycobacterium tuberculosis • Method used for ID—PCR, probe, MALDI-TOF, etc.
Antibiotic Susceptibility Testing • Antibiotic tested • Critical concentration or MIC (Minimum Inhibitory Concentration) • Sometimes multiple levels per antibiotic • Result/interpretation • R=Resistant • S=Susceptible, Sensitive • Method used • Broth (MGIT) • Agar Proportion (AP)
Conclusions • Different labs use different test methods • All labs report results differently • Labs like to use abbreviations • BUT—understanding what type of information is included in a lab report and knowing the keywords to look for can be very helpful • ALSO—If you have questions, call the lab and ask!
Questions? Jessica Gentry Tuberculosis Laboratory Supervisor Indiana State Department of Health email@example.com Phone: (317) 921-5858