ASCP M key terms

A differential staining method that divides bacteria into gram-positive (purple) and gram-negative (pink) groups based on cell wall structure, helping guide identification and early antibiotic choices.

The visible characteristics of a bacterial colony on agar, including size, shape, color, edge, elevation, and hemolysis, used as a first step in identifying an isolate.

Culture media containing substances that inhibit the growth of some organisms while allowing others to grow, such as MacConkey agar favoring gram-negative bacilli.

A test that detects the enzyme catalase by bubbling when hydrogen peroxide is added, commonly used to separate staphylococci (positive) from streptococci (negative).

A test for the enzyme coagulase, which clots plasma; a positive result helps identify Staphylococcus aureus and distinguish it from other staphylococci.

The lowest concentration of an antimicrobial that prevents visible growth of a bacterium in a standardized test, used to classify an isolate as susceptible, intermediate, or resistant.

An enzyme produced by some bacteria that breaks the beta-lactam ring of penicillins and related drugs, making the organism resistant to those antibiotics.

A laboratory test in which blood is inoculated into bottles and incubated to detect bloodstream infection; collection technique and timing strongly affect sensitivity.

Visible damage to cultured cells caused by viral infection, such as rounding, fusion, or detachment, used to detect and identify viruses in cell culture.

The amount of viral genetic material in a sample, usually measured by nucleic acid amplification, used to monitor infection and response to antiviral therapy.

A molecular method that copies a specific piece of nucleic acid many times so it can be detected, widely used for rapid viral diagnosis and quantification.

The development of detectable antibodies in the blood after infection or vaccination, marking a change from a negative to a positive serologic result.

The time after infection before a test can detect the organism or its antibodies, during which results may be falsely negative.

A culture medium with low pH and high dextrose that favors growth of fungi and inhibits many bacteria, commonly used for isolating dermatophytes and yeasts.

A rapid test in which yeast cells are incubated in serum and examined for tube-like outgrowths; a positive result supports identification of Candida albicans.

A fungus that grows as a mold at room temperature and as a yeast at body temperature, a pattern seen in organisms such as Histoplasma and Blastomyces.

A multicellular fungus that forms branching filaments called hyphae and produces spores, often appearing fuzzy or powdery on culture media.

A single-celled fungus that typically forms smooth, pasty colonies and reproduces by budding, distinguishable from molds by its growth form.

A group of microscopic procedures on stool that look for parasite eggs, larvae, cysts, and trophozoites, often using concentration and stained smears.

A dormant, thick-walled stage of some protozoa that allows survival outside the host and is often the infectious form ingested in contaminated food or water.

The active, motile, feeding stage of a protozoan parasite, typically found in fresh specimens and more fragile than the cyst stage.

A stain that colors parasite nuclei and cytoplasm, commonly used on thin blood smears to detect malaria parasites and other blood-borne organisms.

Paired blood films used in malaria diagnosis: the thick smear concentrates parasites for detection, while the thin smear preserves parasite shape for species identification.

A method for detecting pinworm eggs by pressing transparent tape against the perianal skin and examining it microscopically, often collected in the morning.

A protein produced by plasma cells that binds to a specific antigen and helps neutralize or remove it; also called immunoglobulin.

A substance that can be recognized by the immune system and can trigger a specific antibody or cellular immune response.

The specific small region of an antigen that an antibody or T-cell receptor actually binds, determining the specificity of the immune response.

A group of serum proteins that work in a cascade to help destroy pathogens, promote inflammation, and enhance antibody-mediated clearance.

An enzyme-linked immunoassay that uses antibodies or antigens attached to a solid phase and an enzyme label to detect or measure a specific substance.

A technique that separates proteins by size and then uses antibodies to detect specific bands, often used to confirm positive screening results such as HIV tests.

An antibody directed against components of the cell nucleus, commonly tested as a screening marker for autoimmune diseases such as systemic lupus erythematosus.

An exaggerated or inappropriate immune response that causes tissue damage, classified into four types based on the underlying mechanism.

The set of routine checks performed alongside patient testing to confirm that instruments, reagents, and methods are working within acceptable limits before results are reported.

An external program that sends unknown samples to a laboratory and compares its results with those of other laboratories to assess testing accuracy.

A written, approved document that describes exactly how a laboratory test or task is performed, including materials, steps, and acceptance criteria.

The process of adjusting an instrument or method using known standards so that its measurements are accurate and comparable to a reference.

Steps taken to fix the cause of a detected problem and prevent it from happening again, documented as part of quality management.

The interval of test values expected in a healthy population, used to help interpret whether a patient result is normal or abnormal.

A quality rule that compares a current patient result with a previous result from the same patient to flag unexpectedly large changes that may indicate error.