Use of Laboratory and Collection of Specimens

Question 1

What are the reasons we use detection of infectious agents

Answer 1

guideline for treatment

information for individual cases

collated information for general (publications)

Question 2

Why is epidemiology important for clinical information

Answer 2

track resistant isolates (e.g., MRSA)

follow trends in development of resistance

detect or confirm outbreaks related to infectious agents

support control efforts, public health support

Question 3

How do you make the best use of the lab

Answer 3

lab realists correspond to the initial clinical question

decrease frustration - for patients and health care workers (eg., making sure things are properly labeled)

Most cost effective use of lab resources

Speediest results by eliminating delays

Question 4

What are advantages of being a Smart laboratory user

Answer 4

providing information, to make specialized testing to access unusual circumstances ex. if someone has travelled

avoidance of liability of mislabeled specimens, or loss of specimens

Question 5

What are the general principles of specimen collection

Answer 5

send as good quality specimens as possible, avoiding contamination with normal flora as much as possible

make sure both specimen and requisition are labled with patients name, date of birth, and health card number, specimen type, etc.

Put relevant clinical information on the requisition

Question 6

How do you generate the best results and maximize sample quality

Answer 6

use the appropriate transport media to keep the pathogen alive

get specimens to the laboratory rapidly

when in doubt - ask the laboratory (especially if a request is unusual or needs additional testing, or results are unclear, etc.)

when problems arise, work with laboratory staff to fix them

Question 7

Why is stool weird to transport

Answer 7

in stool specimens they begin to turn acidic because the organism is continuing to metabolize and the number of pathogens you are looking for begin to die off due to acidity

Question 8

What are general considerations that need to be considered in specimen collection

Answer 8

whether the specimen will provide useful information

Choice of the type of specimen
( sometimes when a patient is very ill you might want a more invasive specimen because that’s going to give you an answer the quickest. Need to balance invasiveness with the info its gunna tell you)

Instructions for collection by patient (tell and physical instructions)

Need for transport media

Time taken for the specimen to get to the laboratory

Quality of specimen (ex. false positive or negative )

How to intreat the results (predictive values)

Question 9

If a false positive the ___ is low

Answer 9

specificity

Question 10

If its a false negative the ___ is low

Answer 10

sensitivity

Question 11

What are the different specimen collections for urinary tract

Answer 11

mid stream urine

in-out catheter urine

indwelling catheter urine

Question 12

What are the patient instructions for midstream urine

Answer 12

decrease skin contamination by parting labia, retracting foreskin

Cleaning the urethral opening is no longer recommended. first bit of the stream washes out whatever organisms are sitting around the uretha

After passing a few militias collect the specimen in a clean sterile container

Question 13

How is urine specimens transported

Answer 13

transport medium is not requires if urine is transported to the lab within 2 hours or refrigerated t 4C and delivered within 24 hours

Preservatives/transport medium can be used if delivery to a lab is likely to be delayed or transport is prolonged but usually not because the cost is a lot

label the container with the patients name and another identifier and specimen type

Question 14

What do you not collect urine from

Answer 14

bedpans, urinals or catheter bags

Question 15

How to collect urine from in/out catheters

Answer 15

use aseptic technique (dont want to introduce new organisms) to the catheter

discard the first few ml of urine that pass

collect the specimen and send

Question 16

how to collect urine from indwelling catheters

Answer 16

collect the specimen using a needle and syringe after cleaning the collection site with alcohol, and send

they have more organisms and are more difficult to interpret

Question 17

What specimen types are there for respiratory tract specimens

Answer 17

sputum (cough it up)

induced sputum (if you have a dry cough and cant cough anything up)

tracheal aspirate (sedated)

Question 18

how do you collect a respiratory tract specimen if its suspected that a patient has TB

Answer 18

use precautions to prevent spreading infection

don’t have them cough in your face, get them to do it another room

Question 19

What are the patient instructions for sputum collection

Answer 19

decrease contamination by saliva by removing dentures, clean teeth

acid collecting post nasal discharge

deep cough from the chest into the bucket

Question 20

how are teeth cleaned in a sputum collection

Answer 20

Gargling and using mouth with sterile water

no toothpaste because the residue may have fluoride in it which is antibacterial

not tap water, may be contained with legionella or pseudomonas

Question 21

How is sputum collection transported

Answer 21

in a dry sterile container

transport to the laboratory as soon as possible but at least within 24 hours

refrigerate at 4C if there is a delay in delivery

Question 22

When might a sputum collection not be cultured

Answer 22

they may not culture it if there is a degree of contamination with saliva by identification of squamous

Question 23

When is induced sputum collection used

Answer 23

induction of sputum using aline aerosols can be useful if patient cannot produce sputum

sputum produced after bronchoscopy is a good specimen also

need to label because it will look like saliva

Question 24

when is tracheal aspirate collection used

Answer 24

useful in incubated patients, may not be perfect as material may be pooled in the back

specimen collection traps are prone to leaking during transport too (30% of time)

Question 25

How do you collect enteric specimens

Answer 25

stool

Question 26

What are the patient instructions for stool collection

Answer 26

pass stool on clean sry surface, eg., paper or plastic
if liquid into a clean container

place an almond size (with shell) sized portion in the specimen container

Question 27

How is stool transported

Answer 27

transport to lab as soon as possible or refrigerate at 4C (no more than 24 hours)

send stool rather than rectal swabs if possible

Question 28

What are the 3 types of stool transport media

Answer 28

1. for culture use enteric (cary Blair) transport medium
2. for parasites use SAF (formalin, saves and preserves) parasite preservative
3. For cytotoxicity and virology testing (ex. C. diff) use dry sterile container because nucleic acid identification

Question 29

What are swabs used for

Answer 29

throat, wound, urethra

Question 30

What are swabs not used for

Answer 30

abscesses (want a container of puss as its a good transport medium),

fluids,

TB culture (swabs don’t work good, micro bacteria gets in the swab)

Question 31

What are the instructions for using swabs

Answer 31

use a swab only if there is insufficient quantity to collect in a syringe and send in a dry sterile container. some material will be absorbed by the swab

collect purulent material

avoid contamination with surrounding normal flora on skin

Question 32

How do you transport swabs

Answer 32

use an appropriate tranport medium to increase organism survival or for specific organism (eg., Neisseria gonorrhoeae culture, viruses, clamydia)

some instruments use specific swabs (eg., chlamydia and n gonorrhoeae) have specific systems related to their pHs that work well

avoid dry swabs for sending specimens as the organisms will die off

anaerobic swabs are 20x the cost of aerobic swabs and so should be used judiciously (e.g., on deep infected wounds but not on mucous membranes)

Question 33

When to use dry swabs

Answer 33

for making slides

Question 34

when are biopsies or sterile fluids used

Answer 34

tissue

pleural fluid

pericardial fluid

CSF

vitreous fluid

Question 35

What is the instructions for collection of biopsies and sterile fluids

Answer 35

collect in a dry sterile container and send to the lab without delay

labelling must be complete and correct

it is not necessary to add sterile water to biopsies unless they are very small and in danger of drying out ( add a few drops to maintain humidity)

microbiology specimens should never be put in formalin (it kills all the bacteria)

Question 36

How long does it take for microscopy realists to be avaliable

Answer 36

1-2 hours for stat samples

Question 37

How long do culture take for results

Answer 37

may take from overnight to several weeks for some organisms. most are available within 3-5 days

TB takes a week at the fastest
fungi takes awhile too

Question 38

How long does rapid testing (antigen detection take for results)

Answer 38

may be available on the same day