The terms below are defined in the context of the Region X Chlamydia Project. Some of these terms may be used in other settings, with different meanings.A
- The extent to which a measurement is close to the true value.
- Amplification Test
- A test which replicates the genetic material (DNA or RNA) of a microorganism such as Chlamydia from a few copies to millions within a few hours. These amplified (replicated) copies can then be detected, usually by photometry or fluorimetry.
- Analytical Range
- The range of accuracy of a test, e.g. the values (results) of a glucose blood test may range from 0 to 10,000 units, however test A used to detect glucose is only capable of detecting from 100 to 1,000 units, therefore the analytical range of this test is 100 to 1,000 units.
- A chemical substance capable of destroying microorganisms, specifically bacteria.
- A type of serum protein that is produced by the body in response to invasion by foreign proteins, e.g. viruses or bacteria, called antigens. Antibodies assist the body in removing or destroying foreign antigens.
- Foreign substances that stimulate the body to produce antibodies. Such substances may be used to detect antibodies in the blood serum.
- A state where a person is infected with chlamydia but has no clinical symptoms (e.g. friable cervix and/or mucopurulence) of active disease.
- The Association of State and Territorial Public Health Laboratory Directors. The national organization of public health laboratory directors working in state or territorial health departments.
- An antibiotic used to treat chlamydial infections that can be given in a single dose.
- Any small one-celled (unicellular) microorganism. Bacteria vary in shape (morphologically), being spheric (cocci), rod-shaped (bacilli), spiral (spirochetes), or comma-shaped (vibrios).
- A set of specimens, e.g. endocervical swabs, processed and tested during a single run (diagnostic test).
- Cervical Motion Tenderness (CMT)
- Moderate to severe tenderness elicited when the cervix is palpated or manipulated.
- Infection and/or inflammation of the cervix. Can be a sign of chlamydial infection.
- The narrow neck of the uterus, which extends into and can be partially visualized in the vagina. The cervix is a primary site of chlamydia infection and testing in females.
- Chlamydia trachomatis
- Chlamydia trachomatis is the bacterial agent which causes chlamydial infections, the most common sexually transmitted bacterial infection in the United States. While chlamydiae are classified as bacteria, they share some properties of both bacteria and viruses.
- Clinical Laboratory Improvement Act of 1967 (and amendments of 1988) which sets the guidelines for any clinical laboratory testing material obtained from human patients, i.e. blood, tissue, discharge, etc. CLIA is administered through the U.S. Health Care Financing Administration (HCFA).
- Clinical Laboratory
- A laboratory in which tests directly related to the care of patients are performed. Such laboratories use material obtained from patients for testing, as compared with research laboratories, where animal and other sources of test material are also used. Laboratories that accept specimens for testing by referral from separate medical facilities are often called reference laboratories.
- Clinical Laboratory Procedure
- Analytical procedure (test) performed on any specimens (samples) taken from humans and used to diagnose disease or infection.
- Collection Sites
- Locations in the body from which a chlamydia specimen may be taken. These sites include: cervix, urethra, rectum, throat, conjunctiva (eye). Different laboratory tests are sometimes indicated for use on different collection sites.
- Confirmatory Test
- A test which is used to confirm positive screening results thereby eliminating false positive results, improving test specificity. This test employs a different target molecule than screening tests, e.g. C. trachomatis enzyme immunoassays (EIA) typically detect specific lipopolysaccharide (LPS); while direct florescent antibody (DFA) test, used to confirm a positive EIA test, targets the major outer membrane (MOMP) of C. trachomatis. This method is preferred to using a supplemental test (see Supplemental Test).
- A person who has had sexual contact with an individual having a confirmed sexually transmitted disease; often synonymous with ?partner?.
- An artificial specimen with a known value (i.e. positive or negative) which is included in every test run in order to monitor the performance of the test. For example, if your positive control was negative it would invalidate the results of that particular test run and specimens would have to be re-tested.
- Council of State and Territorial Epidemiologist. This is the national organization for epidemiologists working in state or territorial health departments.
- A laboratory test involving the cultivation of microorganisms or cells in a special growth medium.
- Cutoff (CO)
- A mathematically derived calculation in any given immunoassay which is used to determine which specimens are positive (reactive) or negative (unreactive), e.g. generally specimens with values above the CO are positive and those below are negative.
- Detection Limit
- The range (limits) of detection of any test methodology, e.g. C. trachomatis amplification test needs only 1-10 organisms to be presented in order to detect CT, whereas an enzyme immunoassay (EIA) needs 100,000 (10 5) organisms to be present in order to detect CT.
- Diagnostic Test
- A test designed to detect chlamydia in a patient presenting with symptoms or history of exposure, as distinguished from a screening test.
- Direct Fluorescent Antibody Test (DFA)
- The direct detection of chlamydia (antigen) from a specimen (e.g. endocervical swab, etc.) which is placed on a microscope slide and stained using fluorescently labeled chlamydia specific antibody. After proper staining, the slide is viewed under a fluorescent microscope. Chlamydia positive specimens show apple-green elementary bodies in contrast to red background of counterstained cells.
- Disease Intervention Specialist (DIS)
- A trained individual working with test-positive patients and their partners to confirm treatment and identify all other potentially infected individuals. Usually employed by a health department.
- DNA Probe
- See Nucleic Acid Hybridization Test.
- An antibiotic used to treat chlamydial infections. The standard dosage is 100 mg, twice a day, for 7 days.
- Ectopic Pregnancy
- A pregnancy occurring anywhere except in the uterus, usually in the fallopian tubes. A serious, potentially fatal consequence of tubal damage from chlamydial infection.
- Visible columnar epithelial cells that extend onto the outer surface of the cervix. In pregnant women, younger women or women using hormonal contraceptives, ectopy is considered normal. Ectopy increases the risk of acquiring chlamydia by exposing the more vulnerable columnar epithelial cells.
- Enzyme Immunoassay (EIA)
- A laboratory test that detects specific antigens or antibodies rather than the organism, e.g. chlamydia itself.
- An antibiotic used to treat chlamydial infection, especially for pregnant women. The standard dosage is 500 mg orally 4 times a day for 7 days.
- Etiologic Agent
- An agent, e.g., a bacteria or virus that causes disease.
- External Quality Control
- An external control (see control) specimen which is generally shared between multiple laboratories and the results compared for quality control purposes.
- False Negative (Result)
- A test result that indicates the absence of a condition when the condition is actually present (group ?C? in Table I). The rate of occurrence of false negative results varies with the diagnostic accuracy and the specificity of the test or procedure. As the accuracy and specificity of a test increases, the rate of false negatives decreases. Certain tests are known to yield false negative results at a certain rate; in all tests, a small number of false negatives will occur by chance alone.
- False Negative (Rate)
- The rate of occurrence of negative test results in subjects known to have the disease or behavior for which the individual is being tested (see Table I).
- False Positive ( Result)
- A test result that wrongly indicates the presence of a condition when the condition is not present (group ?B? in Table I).
- False Positive (Rate)
- The rate of occurrence of positive test results in tests of individuals know to be free of a disease or disorder for which the individual is being tested (see Table I).
- Fragile, easily irritated, especially prone to bleeding; for example, cervical surface tissue in some chlamydial infections.
- A common sexually transmitted disease most often affecting the genitourinary tract and, occasionally, the pharynx, conjunctiva, or rectum. Infection results from contact with an infected person or by contact with secretions containing the causative organism Neisseria gonorrhea. Sometimes referred to as GC (gonococcus).
- Gray Zone (GZ)
- - An artificially established range (zone) below a diagnostic test?s cutoff (CO) value. The GZ generally ranges from 30-70% below the CO. Specimens in the established GZ are then re-tested by another methodology in order to increase the test sensitivity, i.e. to detect additional positive specimens.
- An assay (test) which detects antigens or antibodies.
- The inability to conceive or carry a fetus to term. Chlamydia related infertility is most often caused by scarring in the fallopian tubes.
- A substance that interferes with the test?s ability to detect the presence or absence of disease. Blood and mucous are examples of potential inhibitors for chlamydia testing.
- Internal Quality Control
- An internal control specimen made up and used by a particular laboratory (see control).
- A package of test reagents, package insert, etc. which enable a laboratory to perform a particular test, i.e. a chlamydia kit would enable a laboratory to test for chlamydia.
- Ligase Chain Reaction (LCR)
- An amplification test for chlamydia and/or gonorrhea. A process whereby a strand of DNA can be cloned (replicated) millions of times within a few hours.
- The lipopolysaccharide in the Chlamydia organism, a part of the organism. The same LPS is present in all chlamydia species, e.g. C. trachomatis, C. psittaci, C. pneumonia, etc. Any test which detects chlamydia LPS would cross react with all chlamydia organisms.
- Diagnostic kits are manufactured in large qualities (lots). As part of quality control, laboratories record all results from each kit and lot in order to monitor for any variations which may occur between lots.
- The average of the numerical results obtained from a series of analyses.
- Major Outer Membrane Protein (MOMP)
- The major outer membrane protein on the Chlamydia organism. The MOMP is species specific, i.e. C. trachomatis is different from C. psittaci, etc. Any test which detects MOMP will only react with each separate species, i.e. C. trachomatis MOMP will not react with C. psittaci.
- Bodily discharge composed of mucous, cellular debris and white blood cells as a result of an infection process such as chlamydia. Mucopurulent appears to have a green or yellow color when viewed on a white cotton swab that has been inserted into the cervical os. Slang: mucopus.
- Mucopurulent Cervicitis (MPC)
- Cervical infection/inflammation characterized by a mucoidpurulent (pus) discharge and friability. Often caused by chlamydia infection but may also occur with many other organisms.
- Nucleic Acid Hybridization Test (DNA Probe)
- Commercial name: Gen-Probe Pace 2 assay. A laboratory test which detects C. trachomatis ribosomal RNA.
- Office of Population Affairs (OPA)
- This is the federal office which administers the Title X family planning program. Part of the Department of Health and Human Services, US Public Health Service.
- Package Insert
- The written pamphlet in every diagnostic test kit which includes instructions for proper use (kit directions) of the kit. In addition, the package insert contains some or all of the following: information on intended use; summary and explanation of the test; principles of the procedure; reagents provided; special precautions; specimen collections, storage and transport; materials provided/not provided with kit; procedural limitations; performance characteristics; results; and quality control.
- Partner Elicitation
- Obtaining the names and means of contacting the sexual partners of an individual with a reportable, laboratory-positive sexually transmitted disease, usually by interviewing the diagnosed client.
- Partner Management (PM)
- A set of activities undertaken by a medical provider and patient aimed at ensuring appropriate clinical disposition of all possible contacts to a sexually transmitted disease. PM may include partner elicitation, notification, referral, treatment and tracking.
- Partner Notification
- The medical care provider advises the sexual partner of an individual with an STD of his/her contact status, usually providing anonymity for the patient.
- Partner Referral
- The provision of written or oral information on the sexual partner of an individual with a reportable, laboratory-positive sexually transmitted disease, about where to obtain medical care for the evaluation or treatment of the disease. Referral can be done by the provider, or, in the case of self-referral, the patient may provide the information to his/her partner.
- Partner Tracking
- The medical care provider provides and documents follow-up of the named sexual contacts of an STD patient (elicitation, notification, referral and/or treatment).
- Partner Treatment
- The sexual partner of an individual with an STD is given indicated treatment for the STD, with or without examination.
- Pelvic Inflammatory Disease (PID)
- A clinical syndrome identified by a range of symptoms including lower abdominal pain and tenderness, bilateral adnexal tenderness, low-grade fever, and cervical motion tenderness. Serious sequelae (consequences) can include infertility, ectopic pregnancy, and chronic pelvic pain. PID can be one of the serious consequences of chlamydial infection.
- Polymerase Chain Reaction (PCR)
- An amplification test for chlamydia. A process whereby a strand of DNA can be cloned (replicated) millions of times within a few hours.
- Predictive Value Negative
- The likelihood that a person with a negative test does not have the disease. See Table I.
- Predictive Value Positive
- The likelihood that a person with a positive test does, in fact, have the disease. See Table I.
- Presumptive Treatment
- Also known as epidemiologic treatment. The treatment of patients suspected of having a disease based on identified risk factors and/or clinical findings, without the confirmation of a positive test result.
- the percentage of people in a given population that have a given disease, e.g. the prevalence of chlamydia in Clinic A is 5%, that is 5 out of 100 individuals in Clinic A are infected with chlamydia. See Table I.
- Proficiency Testing (PT)
- A process in which samples (artificial patient specimens) are sent from a quality assurance or certification organization to participating laboratories for analysis. The true value (results) of the samples are unknown to the participating laboratories. The results are tabulated and compared to all participating laboratories and reported to the enrolling laboratory. PT specimens are an indicator of laboratory performance. PT is a required quality assurance process under laboratory licensing law.
- A test that is qualitative determines the presence or absence of a substance (antibody/antigen), e.g. an EIA detects the presence or absence of chlamydia.
- A test that is quantitative determines the amount of a substance per unit volume or unit weight, e.g. blood glucose normal range 70-115 mg/dl-milligrams per deciliter.
- Quality Assurance Program (QAP)
- A comprehensive set of policies, procedures, and practices used to monitor the services provided in a clinical or laboratory setting. These plans should include protocols for proper record keeping, calibration and maintenance of equipment, monitoring of quality controls and proficiency testing results, and training.
- Quality Control (QC)
- The set of laboratory or clinical procedures designed to ensure the a test is working properly, e.g. test controls, monitor lot-to-lot variation, monitor/run CO values, and etc.
- A substance that produces a chemical reaction in a sample that allows an analyte (the substance being measured) to be detected and measured.
- Reference Laboratory
- See Clinical Laboratory.
- Screening Criteria
- A set of characteristics used to determine which patients in an asymptomatic population should receive a test for chlamydia.
- Screening Test
- A test performed to detect chlamydia in a patient presenting for a routine exam, with no symptoms or known exposure indicating chlamydia infection is likely, as distinguished from a diagnostic test.
- Selective Screening
- Testing for chlamydia in a population using screening criteria, as opposed to universal screening of an entire patient population, or diagnostic testing of patients with symptoms.
- The ability of a test to detect patients who have the disease or condition for which they are being tested. Expressed as the percent of positive cases where disease is correctly identified as present. See Table I.
- The ability of a test to accurately identify patients who do not have the disease or condition for which they are being tested. Expressed as the percent of negative cases correctly identified. See Table I.
- A small sample of something, intended to show the nature of the whole, such as a blood or urine specimen.
- Specimen Adequacy
- The quality of the specimen obtained from the patient judged by the number and type of cells sampled, e.g. in chlamydia testing, an endocervical specimen which contains any endocervical columnar/cuboidal epithelial cells or metaplasitc cells (or greater than 100 erythrocytes (RBC?s) per field at 200X).
- Supplemental Test
- A test which is used to confirm positive screening results. This test employs the same target molecule as the original screening test, e.g. C. trachomatis enzyme immunoassays (EIA) typically detect specific lipopolysaccharide (LPS); the EIA blocking or neutralization assay also target this samemolecule (LPS). As a general rule, results obtained from using one test should be confirmed using an alternate technology (see Confirmatory Test) in order to best decrease the incidence of false positive test results thereby increasing specificity.
- Presenting with clinical signs of disease.
- Title X
- The Federal legislation which supports federally funded family planning clinics; Title X of the Public Health Services.
- Transcription Mediated Amplification (TMA)
- An amplification test for the detection of chlamydia. A process whereby a strand of RNA can be cloned (replicated) millions of times within a few hours.
- Turnaround Time (TAT)
- The amount of time it takes to produce a test result from the time a specimen is received in the laboratory until it is reported out.
- Universal Screening
- Testing for chlamydia in an entire population, regardless of symptoms, risk history, or other factors.
- Inflammation of the urethra.