chapter 29 - infectious diseases Flashcards
What is clinical microbiology?
a subdiscipline of microbiology focussing on the diagnosis of infectious diseases by identifying pathogenic microbes and advising medical providers on treatment
Summarize what working in a biosafety level 4 laboratory environment
BSL-4 is the highest level of biological containment
- whole body sealed suit with an outside air supply and ventilation system
- air locks control all access to the laboratory
- all materials leaving the laboratory is autoclaved or chemically decontaminated
What are some safety standards in labs?
- good personal hygiene
- vaccinated
- usage of personal protective equipment
What are nosocomial infections?
healthcare-associated infection acquired at healthcare facility
What are some risk factors for hospital-acquired infections?
- patients
- newborn infants and elderly
- surgery
How are microbial pathogens identified?
- samples may include blood, urine, feces, sputum, pus
- requires a combination of microbiological immunological and molecular biological techniques
What are immunoassays?
use antibodies specific for pathogens or their products for in vitro tests designed to detect specific infectious agents
What is an antibody titre?
a quantitative measure of antibody level and is defined as the highest dilution or serum at which an antigen-antibody reaction is observed
What is precipitation?
the interaction of a soluble antibody and soluble antigen to form an insoluble complex
(only occurs when antigen and antibody are in equivalent concentrations)
What is agglutination?
visible clumping of a particulate antigen when mixed with antibodies specific for the particulate antigen
these tests are used to identify blood group antigens and many pathogens and pathogen products
What is the difference between direct and indirect immunofluorescence?
direct: antibody targeted against the surface antigen is covalently linked to the fluorescent dye
indirect: presence of a non-fluorescent primary antibody is detected by a fluorescent secondary antibody directed against the non-fluorescent antibody.
Explain the applications of immunoflorescence
- if pathogen contains surface antigens reactive with the antibody, the pathogen cells fluoresce
- fluorescent antibodies can be applied directly to infected host tissues allowing for rapid diagnosis
- fluorescent antibodies can be used in the diagnosis of noninfectious diseases
What is enzyme-linked immunosorbent assay (ELISA)
- enzymes covalently bound to antibody molecules to amplify the signals
- very sensitive immunological assay
- widely used in clinical diagnosis and research applications
What are the three different types of enzyme immunoassays?
- direct: solid phase support, antibodies are connected to antigen from a patient sample
- indirect: antigens are on solid support, antibodies from patient sample are connected to antigens, antibodies from assay are connected to the patients antibodies.
- sandwich: antigens are on a solid support, connected to antibodies from a patient sample, connected to another antigen.
Summarize the mechanisms of rapid tests
- patient specimen is applied to sample well of a support matrix
- capillary pulls liquid sample through matrix, specific antigen (if present) binds soluble labeled antibodies.
- antigen-antibody complexes diffuse through the matrix and bind a line of fixed antibodies
- colored line becomes visible when concentration builds up
