2. Patient to result Flashcards
What is the diagnostic pathway?
- request
- sample collection
- transport of samples
- reception
- safety issues -risks?
- non culture techniques
- culture of clinical samples
- identification and sensitivity
- result
What are sterile sites?
- Blood/bone marrow aspirate
- CSF
- Tissue (meningitis)
- Lower respiratory tract (BAL)
- Bladder
What are non-sterile sites?
- Upper respiratory tract (commensal bacteria)
- Skin
- GI tract
- Vagina
- Urethra (skin commensals and faecal flora)
What are examples of specimens received?
- MSU (main stream urine)
- Blood culture (sepsis)
- Urethral swab (STI)
- Faeces (C.diff)
- Toe nail clippings (fungal infections)
- Sputum (cystic fibrosis)
What are the rules for sample collection?
- take appropriate specimen
- collect before antibiotics are given
- avoid contamination
- label specimens correctly
- complete request form completely
- transport should be asap
What is the bacterial transport media?
STM - Stuarts transport media
- contains charcoal to inactivate any toxic bacterial bi-products
- used for swabs: not fluids
What is the virus transport media?
VTM - viral transport media
- buffered salt solution containing serum
- contains antimicrobials to control overgrowth of contaminating bacteria and fungi
Why should samples be refrigerated at 4 degrees?
to slow down any microbial growth
What is the role of the clinical microbiology reception?
- check specimen/ form
- allocation of unique laboratory number
- macroscopic appearance- discard unsuitable samples
What is the ACDP?
Advisory Committee on Dangerous Pathogens
- has different categories for pathogens: 1,2,3 etc
What is category 1?
A biological agent unlikely to cause human disease
What is category 2?
A biological agent that can cause human disease; hazardous to employees; unlikely to spread in community
What is category 3?
A biological agent that can cause severe human disease; serious hazard; risk of spread in community; prophylaxis
What is category 4?
A biological agent that can cause severe human disease; serious hazard to employees; likely spread in community; no effective treatment
What are non culture techniques?
- direct microscopy
- antigen detection
- PCR
- Serological response
What are culture techniques?
- solid agar
When is direct microscopy used?
- for a clinical sample
- widely use light microscopy
- can use wet preparation; parasite ova and cysts
- can use stained preparations; gram stain for bacteria and yeast
What is antigen detection?
- use antigen detection kits
- contain latex beads coated with specific antibodies for antigen
- if in direct contact with bacteria, then agglutination occurs
What are different types of solid agar?
- basic; nutrient agar
- enriched agar
- selective agar
- differential agar
What is enriched media?
general purpose medium
- horse blood agar
useful for demonstrating haemolysis
- chocolate agar
useful for growing fastidious organisms
What is selective media?
- medium where a selective compound has been added
- inhibit growth of commensals. allow growth of bacteria
- eg.. CCFA - grey colonies
What is differential media?
medium it which an indicator (dye has been added
- CLED
Bromothymol blue ( yellow in acid pH)
