Specimen Collection and Processing Flashcards
How long should the specimen collection be postponed when the patient is under antibiotic therapy?
Wait 1 week after antibiotic therapy
Method for obtaining anaerobic bacteria
Aspiration
Level scheme of prioritization where the specimen is “critical” due to invasive collection or severity of disease
Level 1
Level scheme of prioritization with organisms that easily multiply; processed immediately
Level 1
7 specimens under Level 1 priority
- CSF
- brain
- blood
- heart valves
- pericardial fluid
- bronchoalveolar lavage
- amniotic fluid
Level scheme of prioritization that may contain other organisms
Level 2
Level scheme of prioritization that may be unprotected/unpreserved and may quickly degrade or have rapid overgrowth of contamination, changing the nature of the specimen
Level 2
7 specimens under level 2 priority
- Sputum
- pus
- tissue
- drainage from wounds
- bone
- feces
- stool
Level scheme of prioritization whose specimen requires quantitation (colony counting & quantitative tissue biopsy)
Level 3
2 specimens under level 3 priority
- urine
- catheter tips
Level scheme of prioritization whoses specimen is in a transport media
Level 4
3 specimens under level 4 priority
- feces and urine in preservative
- swabs in holding medium
7 body sites that are normally sterile
- CSF
- serous fluids
- lower respiratory tract
- bladder
- bone marrow
- blood
- tissue
7 body sites that have normal commensal flora
- mouth
- nose
- upper respiratory tract
- gastrointestinal tract
- female genital tract
- urethra
- skin
2 specimens obtained from the upper respiratory tract
- throat cultures
- nasopharyngeal cultures
Bacteria obtained from throat cultures
Group A streptococci
Type of sterile swab used for throat cultures
Calcium alginate
5 infections detected in throat cultures
- streptococcal infections
- whooping cough
- epiglotitis
- oral thrush
- gonorrhoea
Organism that causes oral thrush
Candida albicans
2 bacteria obtained from nasopharyngeal cultures
- Neisseria meningitidis
- Staphylococcus aureus
3 infections detected by nasopharyngeal cultures
- pertussis
- middle ear infections
- indentification of carrier state
4 infections detected by lower respiratory tract specimens
- bronchitis
- pneumonia
- tuberculosis
- histoplasmosis
3 specimens for lower respiratory tract
- sputum
- gastric contents
- transtracheal aspirations
Specimen for lower respiratory tract for children and orderly who cannot cough out sputum
Gastric contents
Specimen for lower respiratory tract when the patient cannot produce gastric contents
Transtracheal aspiration
Time for best specimen of sputum
Early morning (deep cough & no saliva)
What is the time limit of refrigeration of histoplasmosis specimen when it is delayed?
Refrigerate not more than 1-3 hours
Specimen when the physician requires anaerobic culture for lower respiratory tract
Aspirations
Presentation of results for lower repiratory tract
Bartlett’s Classification (sputum only)
4 cells scanned for their presence in the Bartlett’s classification
- squamous epithelial cells (SECs)
- polymorphonuclear neutrophils (PMNs)
- alveolar macrophages (AMs)
- columnar cells (CC)
Interpretation of PMNs in Bartlett’s classification
Bacterial pneumonia
Interpretation of AMs and CCs in Bartlett’s classification
Lower respiratory tract specimen was collected properly
Interpretation of SECs in Bartlett’s classification
Oral flora contamination
Describe prurulent secretions
Greater than 25 PMNs and less than 10 SECs per low power field
Describe oral secretions
Greater than 25 SECs and less than 10 PMNs per low power field
Describe respiratory secretions
Predominance of AMs and CCs (greater than 10 PMNs per low power field)
What should be done with prurulent secretions?
Culture the specimen
What should be done with oral secretions?
Recollect specimen
Specimen for gastrointestinal tract
Rectal swab
Infection detected by gastrointestinal tract specimens
Gastroenteritis
3 methods of collection for urine
- Clean catch midstream specimen
- catheterized specimen
- suprapubic aspiration
Infection detected in urine specimen
Urinary tract infections
What is the time limit of refrigeration of urine specimen if there is delay?
Refrigerate not more than 24 hours
4 screening tests done before colony count of urine
- Griess test
- Triphenyltetrazolium chloride
- Automated methodologies
- Bac-T-Screen
Urine screen test that is a chromophoric test for the presence of organic nitrite compounds
Griess test
Urine screen test as a redox indicator; used to indicate cellular respiration
Triphenylbetrazolium Chloride
Urine screen test for ATP production
Automated methodologies
Calibration of urine inoculating loop
1 uL (0.001 mL) of urine
Value for bacteriuria
Values greater than 1.0x10^5 CFU/mL
Values considered to be contaminated or may represent cultures taken during periods of recovery from UTI after antibiotics have been initiated
Values between 1.0x10^3 and 1.0x10^5 CFU/mL
Unit used in urine colony counting
CFU/mL
Most common bacteria in urine
Escherichia coli
3 infections detected in blood
- bacteremia
- septicemia
- unexplained shock
2 factors that affect positive blood cultures
- stage of the disease
- collection time
Collection time for subacute bacterial endocarditis (SBE)
24-48 hours (3-4 cultures)
Collection time for endocarditis
Anytime
Collection time for brucellosis
During exacerbation of symptoms or elevation of temperature
Collection time for shredding of bacteria in the blood
30-45 mins before the fibrile episode
Volume of blood needed from adults
20-30 mL/culture set (10 mL blood/bottle)
Volume of blood needed for infants
1-5 mL/culture set
3 types of bacteria that will be detected in blood cultures
- aerobic
- anaerobic
- capnophilic
Percent of CO2 during areobic or anaerobic incubation of blood culture
5-10% CO2
Ideal anticoagulant for blood used in blodd culture
Sodium polyanethol sulfonate (SPS) AKA liquoid
What is the time limit for refrigeration of blood sample when there is delay?
Refrigerate for 1-2 hrs
3 susbtances used to identify Peptococcus anaerobius, N. gonorrhoeae, and Gardnerella vaginalis
- sodium amylosulfate
- sodium citrate
- osmotic stabilizer (10-30% sucrose)
3 bacteria identified using sodium amylosulfate, sodium citrate, and osmotic stabilizer (10-30% sucrose)
- Peptococcus anaerobius
- Neisseria gonorrhoeae
- Gardnerella vaginalis
Medium used in blodd culture
Biphasic medium; 1:10 ratio (1 mL blood, 10 mL medium)
Blood culture positive result for gram negative rods
Uniformly turbid with gas bubbles
Blood culture positive for meningococci and pneumococci
Less distinct turbidity
Blood culture positive result for ß-hemolytic streptococci
Cotton ball colonies on top of sedimented red cell with clear upper layer
Blood culture positive result for pathogenic species of staphylococci
Large jelly-like coagulum throughout the broth
Blood culture positive result for bacillus species and saprophytic fungi (non-pathogenic)
Thick pellicle on the surface of the medium with hemolysis
Blood culture positive result for Clostridium species
Marked hemolysis with unpleasant odor and gas under pressure
Blood culture positive result for Bacteriodes species
Less gas than Clostridium spp. but a foul odor
Blood culture positive result for Haemophilus
No change in medium
How long should blood cultures be then declared negative?
After 7 days
Incubation period for Brucellosis
21 days
Skin contaminants in blood culture
Diphtheroid bacilli
4 organisms involved in fatal transfusions
- Pseudomonas (B. anthracis)
- citrobacter
- achromobacter
- late lactose fermenting enteric organisms
How is cerebrospinal fluid collected?
Lumbar puncture
2 bacteria detected in CSF
- N. meningitidis
- H. influenza
Fastidious bacteria
3 transport medium used for specimens with anticipated delay
- Stuart’s medium
- Amie’s medium
- Cary-Blair medium
Transport medium that increases viability of pathogens
Stuart’s medium
Transport medium that is a substitute for Stuart’s medium
Amie’s medium
Transport medium for stool specimens and enteric pathogens
Cary-Blair medium
Specimen for male genital tract
Urethral discharge
3 specimens for female genital tract
- uterine cervix
- urethra
- cervix
Transport medium for genital tract specimen
Gono-Pak/JEM-BEC
