Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Clinical Micro > Lecture 2 diagnostic clinical microbiology > Flashcards

Lecture 2 diagnostic clinical microbiology Flashcards

(50 cards)

Start Studying
1
Q

State the 9 step diagnostic template

A 
1- request
2- sample collection
3- transport samples
4- reception of samples 
5- safety issues
6- non culture methods
7-culture methods
8- ID and sensitivity 
9- result to clinician
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name 5 sterile sites

A 
Blood/bone marrow
CSF
Tissue
Bladder
Lower respiratory tract
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name 5 non sterile sites

A

Upper respiratory tract - c. Albicans, streptococci
Skin - s. Epidermidis
GI tract - coliforms, anaerobes, faecal flora
Vagina - lactobacilli, anaerobes
Urethra tip - skin and faecal flora

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name the main types of specimens received in an NHS micro lab

A 
Mid stream urine
Blood
Urethral swab
Faeces 
Toe nail clippings 
Sputum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What can toe nail clippings be used to identify

A

Fungal and dermatophyte (cause ringworm) infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What can urethral swabs be used to identify

A

STI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What can faeces be used to identify

A

Diagnose for enteropathogenic bacteria,, campylobacter or parasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the most common sample received

A

Mid stream urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why must specimen be collected before antibiotics are given

A

May killbacteria and give a false negative.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Do fastidious organisms need to be transported to the lab quickly

A

Nutrient demanding otherwise will die in transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is important to consider when viewing sputum samples

A

Sputum must travel through upper respiratory tract which isn’t sterile so must know normal flora

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is Stuart’s media used for

A

Bacteria swab transportation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does Stuart’s medium contain and why

A

Nutrient gel

Charcoal to inactivate toxic byproducts from metabolism of nutrient gel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

On what circumstances will a swab need to be refrigerated during transportation?

A

If there is a delay but no more than 24 hrs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the transport media used to transport viral swabs

A

Viral transport media

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does viral transport media contain

A

Buffered salt solution containing serum and contain antimicorbials to control overgrowth to prevent contaminating bacteria and fungi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What differs chlamydial transport media from VTM

A

No antimicrobials which are toxic to chlamydia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What transport media is used for parasitic transportation

A

Merthiolate-iodine-formalin preserves ova and cysts but kills bacteria. Not suitable for protozoal trophozites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the main roles of reception

A

Check specimen and form details filled in properly
Allocate unique lab number
Macroscopic appearance - discard unsuitable ones (DIARRHOEA get solid stool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the key safety issues to consider with patient samples

A

Patient may have HIV or hep b

Category of organism 1,2,3,4.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do lafu keep lab staff safe

Study These Flashcards
A

Negative pressure

HEPA FILTER

22
Q

What are the ACDP categorisation of biological agents

Study These Flashcards
A

Cat 1 - saphrophytic
Cat 2- biological agent cause disease hazardous in lab but not likely to spread in community, effective treatment (s. Aureus, c. Diff, n. Gonorrhoeae, streptococcus pneumoniae)
Cat 3- biological agent cause severe human disease, serious hazard to employees , risk to spread in community, effective treatment
(Mycobacterium tuberculosis )

Cat 4- severe human disease and serious hazard to emploYees. Likely to spread in the community with no effective treatment.
(Ebola)

23
Q

Name 4 non culture techniques

Study These Flashcards
A

Direct microscopy
antigen detection
NAAT (molecular micro)
Serological response

24
Q

What is the gold standard for diagnosis

Study These Flashcards
A

Culture on solid agar

25
What is beneficial about antigen detection
Bacteria doesn't need to be alive to detect antigen
26
Which common STI causing bacterium is commonly identified using serological response testing
Treponema pallidum cause syphilis Look for IgM and IgG response.
27
What are nucleic acid amplification tests for
Useful for slow growing or difficult microrogansims (hep b/c, HIV, mycobacteria) Also for MRSA screening
28
Why are NAAT methods better than serological
Greater sensitivity
29
Name some examples of NAAT
Polymerase chain receptor (PCR) Ligase chain reaction (LCR) Nucleic acid sequence-based amplification (NASBA) Strand displacement amplification (SDA)
30
What does ligase chain reaction involve
Hybridisation of two oligonucleotide probes at adjacent positions on a strand of target DNA which are then joined by thermostable ligase enzyme.
31
What does nucleic acid sequence based amplification involve
Use RNA as a target and utilise 3 enzymes simultaneously: reverse transcriptase, RNAase H and DNA-dependent RNA polymerase
32
What does strand displacement amplification involve
Utilise oligonucleotide primers containing a restriction enzyme site, DNA polymerase and a restriction enzyme at constant temp to produce exponential amplification of the target
33
When would you use a wet preparation
View parasite ova and cysts (faeces)
34
Name a common fluorescent stain used to detect mycobacterium tuberculosis in clinical specimens
Auramine
35
Name 3 organisms that can be identified using the non culture technique, antigen detection
Haemophilus influenzae Streptococcus pneumoniae Neisseria meningitidis
36
What is the benefit of antigen detection
Bacteria don't need to be alive
37
What does antigen detection involve
Bacteria e.g n. Meningitidis in CSF Latex beads have specific antibody for bacteria bound Agglutination of carrier particles
38
Antigens can only be detected using co-agglutination. True or false?
FALSE. Immunofluorescence for influenza virus or RSV respiratory sample ELISA for chlamydia trachomatis for urogenital specimens Enzyme immunoassay (EIA) for s.pnuemoniae for urogenital specimens/ C. difficile toxin in faeces
39
Name 4 different types of agar
Basic e.g nutrient Enriched - take nutrient and add horse blood Selective e.g contain antimicrobial Differential e.g, MSA, s aureus yellow, s epidermidis white
40
What percentage of horse blood agar is horse blood
5-7%
41
How is chocolate agar made
Heat blood and add to agar so x and v factors are released. H. Influenzae and n gonorrhoeae are grown on this
42
Name an example of selective media
CCFA (cycloserine, cefoxitin fructose agar) for C. difficile detection Cycloserine and cefoxitin are antimicrobial and selective for c diff as kill normal faecal commensals.
43
Give an example of differential agar
CLED (cystine lactose electrolyte deficient agar) Look for E. coli ferment lactose which produce acid, turn bromothymol blue to yellow. Differentiation of enterobacteriaceae
44
State the 4 levels of ID
Stage 1 Basic microscopic e,g, gram stain (e,.g gram neg rod) Stage 2 generic basic tests such as macroscopic and microscopic (e,g enterobacteriaceae/coliforms) (Most clinical specimens) Stage 3 full - Basic ID plus additional tests e,g. API/MALDI-TOF (e.g. E.coli) Stage 4 (for outbreaks) full plus genetic fingerprinting ( ecoli 0157)
45
What haemolysis does s pyogenes do on blood afar
Beta haemolytic (1mm, entire edge)
46
Benefit of MALDI TOFF (mass spec) over API
API takes 24 to 48 hrs | MALDI toff can take few mins
47
How can genetic fingerprinting/molecular typing be done
Pulsed field gel electrophoresis (PFGE) | Restriction enzymes chop up whole bacterial genome, and can compare the bands on a gel to identify strain
48
Which methodology is followed for sensitivity testing
EUCAST | EUROPEAN COMMITTEE ON ANTIMICROBIAL SUSCEPTIBILITY TESTING
49
What is sensitivity testing for
To identify sensitivity or resistance of clinical pathogens, provides national standardised sensitivity / resistance data, epidemiologically useful
50
What machines do labs use to perform antimicrobial sensitivity testing
VITEK 2. Strips contain antibitoics so put bacteria into the strip and put into a machine Sensitivity patterns in 30 mins. Can use disc susceptibility methodology using agar.

Clinical Micro (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions