infectious diseases
Introduction to Laboratory Diagnosis of Infectious Disease
Introduction
Laboratory tests may identify organisms directly (eg, visually, using a microscope, growing the organism in culture) or indirectly (eg, identifying antibodies to the organism). General types of tests include Microscopy None Culture None Immunologic Tests for Infectious Disease (agglutination tests such as latex agglutination, enzyme immunoassays, Western blot, precipitation tests, and complement fixation tests) Nucleic Acid–Based Identification Methods for Infectious Disease None Non-Nucleic Acid–Based Identification Methods for Infectious Disease None Culture is normally the gold standard for identification of organisms, but results may not be available for days or weeks, and not all pathogens can be cultured, making alternative tests useful. When a pathogen is cultured and identified, the laboratory can also assess its Susceptibility Testing to antimicrobial drugs. Sometimes molecular methods can be used to detect specific resistance genes. Some tests (eg, Gram stain, routine aerobic culture) can detect a large variety of pathogens and are commonly done for many suspected infectious illnesses. However, because some pathogens are missed on these tests, clinicians must be aware of the limitations of each test for each suspected pathogen. In such cases, clinicians should request tests specific for the suspected pathogen (eg, special stains or culture media) or advise the laboratory of the suspected organism(s) so that it may select more specific tests. Microorganism Microorganism Microscopy Microscopy Culture Culture NAAT NAAT Antigen Detection Antigen Detection Antibody Detection Antibody Detection Ehrlichiosis and Anaplasmosis None ✓ ✓ ✓ Anthrax None ✓ ✓ ✓ Overview of Bartonella Infections None ✓ ✓ ✓ Pertussis None ✓ ✓ ✓ Lyme Disease None ✓* ✓* ✓ Brucellosis None ✓ ✓ ✓ ✓ Chlamydia and Mycoplasmal Mucosal Infections None ✓ ✓ Botulism None ✓ ✓ ✓ Clostridioides (formerly Clostridium) difficile–Induced Diarrhea None ✓ ✓ ✓ Tetanus None ✓ ✓ Diphtheria None ✓ Q Fever None ✓ ✓ Erysipeloid None ✓ ✓ Tularemia None ✓ ✓ Haemophilus Infections None ✓ ✓ Helicobacter pylori Infection None ✓ ✓* ✓ Kingella Infections None ✓* ✓ ✓ Klebsiella, Enterobacter, and Serratia Infections None ✓ ✓ Legionella Infections None ✓ ✓ ✓ ✓ Leptospirosis None ✓* ✓ ✓ Listeriosis None ✓ ✓ ✓ Chlamydia and Mycoplasmal Mucosal Infections None ✓ ✓ Meningococcal Diseases None ✓ ✓ ✓ Nocardiosis None ✓ ✓ ✓ Rhodococcus equus ✓ ✓ Rickettsial species ✓ ✓ Streptococcal Infections None ✓ ✓ ✓ ✓ Syphilis None ✓ ✓ ✓ Whipple Disease None ✓ ✓ Cholera None ✓ ✓ Plague and Other Yersinia Infections None ✓ ✓ ✓ ✓ Adapted from Bennett JE, Dolin R, Blaser MJ: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th Edition. Elsevier, 2020. * Test not widely available in clinical practice. NAAT=Nucleic Acid Amplification Test Microorganism Microorganism Microscopy Microscopy Culture Culture NAAT NAAT Antigen Detection Antigen Detection Antibody Detection Antibody Detection Nontuberculous Mycobacterial Infections None ✓ ✓ ✓* Tuberculosis (TB) and ulcerans ✓ ✓ ✓ Mycobacterium leprae ✓ ✓ ✓ Adapted from Bennett JE, Dolin R, Blaser MJ: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th Edition. Elsevier, 2020. * Test not widely available in clinical practice. NAAT=Nucleic Acid Amplification Test Microorganism Microorganism Microscopy Microscopy Culture Culture NAAT NAAT Antigen Detection Antigen Detection Antibody Detection Antibody Detection Aspergillosis None ✓ ✓ ✓ ✓ Blastomycosis None ✓ ✓ ✓ ✓ ✓ Candidiasis None ✓ ✓ ✓ Coccidioidomycosis None ✓ ✓ ✓ ✓ ✓ Cryptococcosis None ✓ ✓ ✓ ✓ Overview of Dermatophytoses None ✓ ✓ Histoplasmosis None ✓ ✓ ✓ ✓ ✓ Seborrheic Dermatitis None ✓ ✓ Mucormycosis None ✓ ✓ ✓ Pneumocystis jirovecii Pneumonia None ✓ ✓ ✓ Sporotrichosis None ✓ ✓ ✓ Adapted from Bennett JE, Dolin R, Blaser MJ: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th Edition. Elsevier, 2020. NAAT=Nucleic Acid Amplification Test Microorganism Microorganism Microscopy Microscopy Culture Culture NAAT NAAT Antigen Detection Antigen Detection Antibody Detection Antibody Detection Adenovirus Infections None ✓* ✓ ✓ BK virus ✓ ✓ COVID-19 None ✓ ✓ Cytomegalovirus (CMV) Infection None ✓ ✓ ✓ ✓ Overview of Enterovirus Infections None ✓ ✓ ✓ Infectious Mononucleosis None ✓ ✓ Overview of Chronic Hepatitis A, B, C, D and E ✓ ✓ ✓ Herpes Simplex Virus (HSV) Infections None ✓ ✓ ✓ ✓ Roseola Infantum None ✓ ✓ Human Immunodeficiency Virus (HIV) Infection None ✓ ✓ ✓ Human Papillomavirus (HPV) Infection None ✓ ✓ Influenza None ✓ ✓ Progressive Multifocal Leukoencephalopathy (PML) None ✓ ✓ LaCrosse virus ✓ ✓ Lymphocytic Choriomeningitis None ✓ ✓ Measles None ✓ ✓ Mpox (Monkeypox) None ✓ ✓ Mumps None ✓ ✓ Viral gastroenteritis None ✓ ✓ Parainfluenza Virus Infections None ✓ ✓ Erythema Infectiosum (Parvovirus B19 Infection) None ✓ ✓ Powassan virus None ✓ ✓ Rabies None ✓ ✓ ✓ ✓ Respiratory Syncytial Virus (RSV) and Human Metapneumovirus Infections None ✓ ✓ ✓ Rubella None ✓ St Louis encephalitis virus ✓ ✓ Tickborne encephalitis virus ✓ Chickenpox None ✓ ✓ ✓ ✓ West Nile Virus None ✓ ✓ Zika Virus (ZV) Infections None ✓ ✓ Adapted from Bennett JE, Dolin R, Blaser MJ: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th Edition. Elsevier, 2020. * Test not widely available in clinical practice. NAAT=Nucleic Acid Amplification Test Microorganism Microorganism Microscopy Microscopy Culture Culture NAAT NAAT Antigen Detection Antigen Detection Antibody Detection Antibody Detection Babesiosis None ✓ ✓ ✓ Cryptosporidiosis None ✓ ✓ ✓ Cyclosporiasis None ✓ ✓ Amebiasis None ✓ ✓ ✓ ✓ Pinworm Infestation None ✓ Giardiasis None ✓ ✓ ✓ Intestinal nematodes ✓ ✓ ✓ Leishmaniasis None ✓ ✓ ✓ ✓ Malaria None ✓ ✓ ✓ Scabies None ✓ Taenia Solium (Pork Tapeworm) Infection and Cysticercosis None ✓ ✓ Toxocariasis None ✓ ✓ Trichinosis None ✓ ✓ African Trypanosomiasis None ✓ ✓ Adapted from Bennett JE, Dolin R, Blaser MJ: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th Edition. Elsevier, 2020. NAAT=Nucleic Acid Amplification Test 