Lecture15: Overview of the Clinical Microbiology Laboratory Flashcards
1
Q
When working with specimen specimen should
A
- Represent diseased area and other appropriate sites
- be large enough for carrying out a variety of diagnostic tests
- be collected in a manner that avoids contamination
- be forwarded promptly to clinical lab
- be obtained prior to administration of antimicrobial agents, if possible.
2
Q
Standard Microbial Practices
A
- Persons must wash their hands after working with potentially hazardous materials and before leaving the laboratory
- Eating, drinking, smoking, handling of contact lenses, apply cosmetics, and storing food for human consumption must not be permitted in laboratory
- Mouth pipetting is prohibited; mechanical pipetting devices must be used
- Policies for safe handling of sharps (such as needles, scalpels, pipettes, and broken glassware) must be developed and implemented
- Procedures must be developed and implemented to minimize the creation of splashes and/or aerosols
- Work surfaces must be decontaminated with appropriate disinfectant after completion of work and after any spill or splash of potentially infectious material
- All cultures, stocks, and toher potentially infectious materials must be decontaminated using an effective method before disposal
- A sign incorporating the universal biohazard symbol must be posted at the entrance to the laboratory when infectious agents are present
- Persons must report all injuries incurred in laboratory to the laboratory supervisor as soon as possible
3
Q
Microbiology Risk Groups
A
4
Q
Specimen collection
A
- Numerous methods used; choice of methods depends on specimen
- Specimen should represent the diseased area
- quantity should be adequate
- collection to avoid contamination
- proper container, promptly sent to laboratory
- obtain specimen before antimicrobial treatment
5
Q
- Identification of Microorganisms from Specimen
- Direct vs. Indiret indentification methods
A
6
Q
- Direct identification methods
- growth and biochemical characteristics
- microscopy
- molecular methods
- bacteriophage typing
- immunologic tests
- Indirect identification methods
- serology
- immunogluorescence
A
7
Q
Example of some bacteria that are not routinely cultured
A
- Rickettsias, chlamydiae, and mycoplasmas
- these are identified with special stains, immunologic tests, or molecular methods such as PCR
8
Q
Rapid Methods of Identification
A
9
Q
Rapid Methods of Identification
A
- Manual biochemical systems
- e.g., API 20 E system
- Mechanized/automated systems
- Immunologic systems
10
Q
how are speciment fixed for microscopy
A
- wet-mounts
- heat-fixed
- chemically fixed
11
Q
- Choice of microscopy depends on possible pathogen
- ex.?
A
- Dark-field microscopy
- Detection of spirochetes in skin lesions associated with syphilis
- Fluorescence microscopy
- Direct microscopic of specimens to detect fungi
- (note stains that are often used)
- Gram stain and acid fast fast stain
12
Q
Monoclonal Antibodies (mAB)
A
- Produced by hybridoma cells
- “Immortal” cancerous B cell fused with an antibody-producing normal B cell
- Recognize a single epitope
13
Q
How are monoclonal antibodies (Mabs) produced
A
- a mouse is injected with a specific antigen that will induce antibodies against that antigen
- The spleen of the mouse is removed and homogenized into a cell suspension. The suspension includes B cells that produce antibodies against the injected antigen
- The spleen cells are then mixed with myeloma cells that are capable of continuous growth in culture but have lost the ability to produce antibodies. some of the antibody-producing spleen cells and myeloma cells fuse to form hybrid cells. These hybrid cells are now capable of growing continuously in culture while producing antibodies
- The mixture of cells is placed in a selective medium that allows only hybrid cells to grow
- hybrid cells proliferate into clones called hybridomas. The hybridomas are screened for production of the desired antibody
- The selected hybridomas are then cultured to produce large quantities of monoclonal antibodies
14
Q
Chimeric Mabs
A
- Genetically modified mice that produce Ab with a human constant region
15
Q
Humanized Mabs
A
Mabs that are mostly human, except for mouse antigen-binding