This document discusses key considerations for proper specimen collection including differential diagnosis, appropriate tests, collection methods, transport medium, labeling, and timing. It emphasizes the importance of advance planning, collecting adequate and appropriate specimens, sufficient documentation, biosafety, correct packaging, rapid transport, and communication of results. Specific guidelines are provided for collecting and transporting various specimen types including urine, stool, respiratory, blood, and cerebrospinal fluid.
2. Specimen collection: key issues
What is your differential diagnosis?
What test(s) you should conduct?
How to collect appropriate samples ?
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3. Successful laboratory investigations
Advance planning
Collection of adequate and appropriate specimens
Sufficient documentation
Biosafety and decontamination
Correct packaging
Rapid transport
Choice of a laboratory that can accurately perform the tests
Timely communication of results
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4. Transport medium
Allows organisms (pathogens and contaminants) to survive
Non-nutritive - does not allow organisms to proliferate
For bacteria – i.e., Cary Blair
For viruses - virus transport media (VTM)
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6. Why a urine
specimen
? Urinary Tract Infection (UTI)
◦ Frequency
◦ Urgency(An immediate
unstoppable urge to urinate)
◦ Dysuria (painful urination)
◦ Hematuria(blood in urine)
◦ Flank pain
◦ Fever
Culture = ? Bacteria growing
Sensitivity = which antibiotics are effective
Midstream Urine
Sterile Catheter Specimen
(never from bag)
Random
Clean
Female ?
Menstrual details
Tested for:
◦ Specific gravity
◦ pH
◦ Albumin
◦ Glucose
◦ Microscopic exam
To lab 15-20min post collection
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7. Stool Specimen
Analysis of fecal material can detect pathological conditions i.e:
infection, hemorrhage, tumors.
Tests
◦ Occult Blood
◦ Bacteria
◦ Ova & Parasites
Note the:
1-Color
◦ Melena
(black stools)
2-Odor
3-Consistency
Medical aseptic technique
To lab on time
Labelling /Documentation
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8. Stool samples for bacteria
Timing
◦ during active phase
Method
◦ Cary-Blair medium
◦ For Ag detection/PCR – no transport medium
Storage
◦ refrigerate at 4oC if testing within 48 hours, store at -15oC for Ag detection and PCR
Transport
◦ 4oC (do not freeze); dry ice for Ag, PCR detection
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9. Stool samples for parasites
Timing
◦ as soon as possible after onset
Sample amount and size
◦ at least 3 x 5-10 ml fresh stool from patients and controls
Storage
◦ refrigerate at 4oC; store at -15oC for Ag detection and PCR
Transport
◦ 4oC (do not freeze); dry ice for antigen detection and PCR
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10. Respiratory Tract
Tests to determine infection
◦ Throat cultures
◦ Sputum specimens
Upper respiratory/ throat infections
Throat swabs
◦ before meal or 1 hr after meal
◦ Wash hands, glove
◦ Tilt head backward
◦ “ah” ( if pharynx not visualized, tongue depressor, anterior 1/3 of tongue)
◦ Don’t contaminate
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11. Nose & Throat cultures
Nose, Oropharynx & tonsillar
Sterile swab
Insert swab into pharyngeal region
Take swab from reddened areas/ exudate
Culture determines pathogenic microorganisms
Sensitivity determines the antibiotics to which the
microorganisms are sensitive or resistant
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12. Sputum collection
Ordered to identify organisms growing in sputum
Culture & Sensitivity
AFB (acid fast bacilli)
3samples in 3 consecutive days, early morning
◦ Cough effectively,avoid postnasal discharge and saliva
◦ 1 ml minimum volume
Record
◦ Color
◦ Consistency (thickness)
◦ Amount
◦ Odor
◦ Document date & time sent to lab.
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13. Blood for smears
Collection
Capillary blood from finger prick
◦ make smear
◦ fix with methanol
Handling and transport
Transport slides within 24 hours
Do not refrigerate (can alter cell morphology)
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14. Blood for cultures
Collection
Requires aseptic technique
Venous blood
◦ infants: 0.5 – 2 ml
◦ children: 2 – 5 ml
◦ adults: 5 – 10 ml
Collect within 10 minutes of
fever
◦ if suspect bacterial endocarditis:
3 sets of blood culture
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15. Blood for cultures
Handling and Transport
Collect into bottles with infusion broth
◦ change needle to inoculate the broth
Transport upright with cushion
◦ prevents hemolysis
Wrap tubes with absorbent cotton
Travel at ambient temperature
Store at 4oC if can’t reach laboratory in 24h
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17. CSF
Handling and transportation
Bacteria
◦ Medium pre-warmed to 25-37°C before inoculation
OR
◦ transport at ambient temperature (relevant pathogens do not
survive at low temperatures)
Viruses
◦ transport at 4-8oC (if up to 48hrs or -70oC for longer duration)
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