4. SPECIMEN COLLECTION Flashcards
When should a specimen ideally be collected for diagnostic testing?
During the acute or early phase of illness.
What should be done if a specimen is collected after the initiation of antimicrobial therapy?
Use counteractive measures such as adding penicillinase or diluting the specimen.
Why are swabs generally considered poor specimens?
Swabs are prone to contamination and often do not collect enough material, except for nares and throat specimens.
Where should lesions, wounds, and abscesses be collected from for optimal results?
From the advancing margin of the lesion, preferably by aspiration.
What is an important transport guideline for specimens?
Specimens should be transported promptly or stored appropriately to prevent degradation of the suspected organism.
What type of specimen is unacceptable if used for anaerobic culture?
Specimens from sites known to have anaerobes as part of the normal flora, like the vagina or mouth
Why is a specimen received in fixative like formalin unacceptable for culture?
Formalin kills any microorganisms present, rendering the specimen unsuitable for culture.
What should be done with duplicate specimens from the same source and patient on the same day?
Only one specimen should be processed.
EXCEPT FOR BLOOD CULTURES
What makes expectorated sputum specimens unacceptable for culture?
If Gram stain reveals fewer than 25 white blood cells (WBCs) and more than 10 epithelial cells per low-power field (LPF) with mixed bacterial flora.
What is important to consider when selecting the anatomical site for specimen collection?
The correct anatomic site must be selected for specimen collection.
How should a specimen be collected to minimize contamination?
Using the proper technique and supplies with minimal contamination from normal biota.
Why is it important to collect an appropriate quantity of specimen?
To ensure enough material is available for testing.
When should a specimen be collected in relation to antimicrobial therapy?
Before the administration of any antimicrobial agent.
What should be considered when packaging a specimen for transport?
Package in a container or transport medium designed to maintain viability and avoid hazards.
What should be done when submitting swabs for direct smear and culture?
Submit two swabs: one for direct smear and one for culture.
What are some reasons a specimen might be rejected for testing?
Unidentified or improperly labeled specimens, information mismatch between the label and requisition, improper transport temperature, or not using the proper medium/container.
Why would a leaking specimen be rejected?
Leakage could compromise specimen integrity and safety.
What should be done if transport time exceeds 2 hours post-collection?
If the specimen is not preserved, it may be rejected for exceeding the acceptable transport time.
What happens to dry swabs submitted for culture?
They will be rejected since microorganisms may not survive on a dry swab.
Why should a specimen smeared on a slide not be submitted for culture?
This is not the proper specimen type for culture.
What is done with a specimen that would produce questionable medical value information (e.g., Foley catheter tip)?
It may be rejected for testing.
What should be done if a Gram stain of expectorated sputum reveals fewer than 25 WBCs and more than 10 epithelial cells per low-power field with mixed bacterial flora?
The specimen will be rejected for testing.
How long should specimens that are not processed immediately be refrigerated before discarding?
Specimens should be refrigerated for 3 days before being discarded.
In what type of containers should specimens be collected?
Sterile containers (except stool specimens).
Stool specimen - ok lang na di sterile as long as clean leak proof daw siya
How should stool specimens be collected?
In clean, leakproof containers.
What types of swabs are used for upper respiratory tract, external ear, eye, and genital tract specimens?
Cotton, Dacron, or calcium alginate swabs.
What issue can arise with cotton-tipped swabs?
Excessive fatty acids that may be toxic to certain bacteria.
What patient information must be included on the specimen label?
Name,
identification number,
room number,
physician,
culture site,
date and time of collection.
What information must be included on the requisition form for a specimen?
Patient’s name,
age (or date of birth),
gender,
room number,
physician’s name and address,
specific anatomic site,
date and time of specimen collection,
clinical diagnosis or relevant history,
antimicrobial agents (if applicable), and
name of the individual transcribing orders.
How quickly should specimens ideally be transported to the laboratory?
Ideally within 30 minutes, preferably within 2 hours.
What is the recommended transport time for anaerobic bacteria specimens?
No more than 10 minutes.
What is the recommended transport time for cerebrospinal fluid (CSF) specimens?
Immediately, preferably within 15 minutes.
What factors can affect the recovery of certain organisms during transport?
Presence of oxygen (anaerobic bacteria), changes in temperature (Neisseria meningitidis), and
changes in pH (Shigella).
What should be used if transportation of specimens is delayed for more than 2 hours?
Special preservatives or holding media.
What are the requirements for specimen containers during transport?
Containers must be leak-proof and placed in sealable, leak-proof plastic bags.
How should patient specimens or culture isolates be packaged for shipping?
They must be triple packaged and marked with a biohazard symbol.
When should specimens be transported to the laboratory?
Immediately after collection.
Which specimens should be transported immediately at room temperature?
Body fluids,
bone,
inner ear,
corneal scrapings,
foreign bodies,
gastric aspirate,
suprapubic aspirate of urine,
prostatic sample.
How should cerebrospinal fluid (CSF) specimens be transported?
Within 15 minutes at room temperature.
How quickly should blood and bone marrow specimens be transported, and at what temperature?
Within 2 hours at room temperature.
What is the transport condition for abscess, outer ear, conjunctiva, genital tract, respiratory tract, hair, nail, skin scrapings, and tissue specimens?
Within 24 hours at room temperature
How should gastric biopsy specimens be transported?
Immediately at 4°C.
What is the transport condition for indwelling or straight catheter urine samples?
Within 2 hours at 4°C
How should rectal swab, stool culture, and clean-voided midstream urine samples be transported?
Within 24 hours at 4°C
Which specimens should be transported Within 15 minutes at Room Temperature
CSF
Which specimens should be transported Within 2 hours at Room Temperature
Blood and Bone Marrow specimens
Which specimens should be transported Within 24 hours at Room Temperature
Abcess,
Outer ear,
Conjunctiva specimens,
Genital tract specimens (for urethral specimens, within 2 hours using JEMBEC),
Hair,
Nails or Skin Scrapings,
Respiratory Tract specimens,
Tissue specimen
Which specimens should be transported Immediately at 4°C
Gastric Biopsy
Which specimens should be transported Within 2 hours at 4°C
Indwelling catheter (urine sample),
Straight catheter (urine sample)
Which specimens should be transported Within 24 hours at 4°C
Rectal swab,
Stool culture,
clean voided midstream urine
Most commonly used, may contain fatty acids that can be detrimental to microbial growth.
cotton-tipped swab
Which type of swab is an excellent substitute but should never be used in Herpes Virus detection?
Calcium alginate-tipped swab.
Why shouldn’t calcium alginate-tipped swabs be used for direct antigen detection?
They interfere with the extraction reagents and may be toxic to some chlamydia species.
Which swab is used for the delayed recovery of Group A streptococci from throat culture?
Polyester-tipped swab (Dacron or Rayon).
How can the viability of Group A streptococci be maintained for 3 days using a polyester-tipped swab?
By incorporating a small amount of silica gel in a glass tube containing the polyester swab.
What are the types of swabs according to the applicator used?
Wooden applicator stick and Nichrome or thin aluminum wire.
Kinds of Swabs According to Tip Used
Cotton-tipped Swab
Calcium Alginate-tipped Swab
Polyester-tipped Swab (DACRON or RAYON)
At what temperature should specimens be refrigerated?
4°C-6°C.
For how long can swabs from wounds, urogenital tract, throat, and rectum, as well as feces or sputum, be refrigerated?
2-3 hours.
How long can urine specimens be refrigerated for preservation?
At least 24 hours.
What should be done with CSF from patients suspected of having meningitis?
It should be examined at once.
How should specimens for viral isolation be handled?
Refrigerated immediately, but never frozen.
What preservative is used to maintain the bacterial population in urine at room temperature for 24 hours?
Boric acid.
What transport media should be used for stools if the delay in processing exceeds 2 hours?
Cary-Blair transport media.
What is the required handling for stools for Clostridium difficile toxin assay?
Collected without a preservative, refrigerated, and frozen at −70°C if delayed longer than 48 hours.
What is the purpose of transport or holding media for specimens?
To prolong the survival of microorganisms during significant delays in culturing, without allowing their multiplication.
Name some commonly used transport media for specimen preservation.
Stuart’s medium,
Amies medium,
Cary-Blair medium,
Transgrow medium,
JEMBEC.
What is the purpose of charcoal in transport media
To absorb fatty acids that could kill fastidious organisms like Neisseria gonorrhoeae or Bordetella pertussis.
contains selective agar and a carbon dioxide (CO2)–generating tablet
N. gonorrhoeae
JOHN E. MARTIN BIOLOGICAL ENVIRONMENTAL CHAMBER (JEMBEC)
What is the purpose of anticoagulants in specimen collection?
To prevent clotting of specimens such as blood, bone marrow, and synovial fluid.
What concentration of sodium polyanethol sulfonate (SPS) is used in blood culture media?
0.025%.
Samples that can also be inoculated into a
blood culture broth bottles
synovial and peritoneal fluids
Why is the ratio of specimen to SPS important?
It ensures proper preservation and growth of microorganisms, especially for Neisseria spp. and some anaerobic bacteria.
What is the required blood volume for adults and children when using 0.025% SPS in blood culture?
Adults: 10-30 mL.
Children: 5-10 mL.
used for blood culture media because Neisseria spp. and some anaerobic bacteria are particularly sensitive to higher concentrations
0.025% SODIUM POLYANETHOL SULFONATE (SPS)
What are the reasons for using 0.025% SPS as the preferred anticoagulant for blood cultures?
a. Inhibits phagocytosis and complement activation.
b. Neutralizes aminoglycoside antibiotics.
c. Neutralizes the bactericidal effect of plasma.
d. Precipitates fibrinogen, β-lipoproteins, and β-1-C globulin.
Which microorganisms’ growth can be inhibited by 0.025% SPS?
Neisseria gonorrhoeae
Neisseria meningitidis
Gardnerella vaginalis
Streptobacillus moniliformis
Peptostreptococcus anaerobius
How can the inhibitory effect of SPS be neutralized?
By adding 1% gelatin.
used for viral cultures and isolation of Mycobacterium spp. from blood.
Heparin
Why should Heparin be used cautiously in microbiology?
It may inhibit the growth of gram-positive bacteria and yeast.
Which anticoagulants should not be used in microbiology?
citrate and Ethylenediaminetetraacetic Acid (EDTA)
At what temperature should urine, stool, viral specimens, sputa, swabs, and foreign devices be stored?
Refrigerator temperature (4°C).
How should stool specimens for Clostridium difficile toxin be handled?
If not transported immediately, refrigerate. If delayed more than 2 hours, use Cary Blair transport medium. If delayed longer than 48 hours, freeze at −70°C.
How long can stool specimens for the isolation of Clostridium difficile toxin be stored at 4°C?
Up to 3 days.
What is the storage guideline for specimens suspected to contain anaerobic bacteria?
Specimens should never be refrigerated.
What is the ideal temperature to store CSF samples for Gram staining, culture, and sensitivity tests?
Incubator temperature (35°C).
At what temperature should serum for serologic studies be stored for short-term preservation?
-20°C.
For long-term storage of tissue specimens or serum, what temperature should be used?
-70°C.
At what temperature should fecal specimens for C. difficile toxin studies be stored if storage is longer than 3 days?
-70°C
What specimen types should be stored at room temperature (22°C-25°C)?
Specimens for anaerobic culture, sterile body fluids, genital specimens, and swabs (ear and eye).
What characterizes Level 1 specimens?
Critical or invasive specimens, potentially life-threatening illness, require immediate processing.
What type of specimens are categorized as Level 2?
Unprotected specimens that may quickly degrade or have overgrowth of contaminating flora.
What is the characteristic of Level 3 specimens?
Require quantitation, and delays may adversely affect the accuracy of quantitation.
What type of specimens fall under Level 4?
Specimens that arrive in the laboratory in holding or transport media.
How should specimens for acid-fast bacilli that need to be digested and decontaminated be handled?
They can be refrigerated and processed once per day.
How are acid-fast, viral, and fungal specimens typically processed?
They are usually batched for processing at one time.
Level 1 specimens examples
Amniotic fluid
Blood
Brain
Cerebrospinal fluid
Heart valves
Pericardial fluid
Level 2 specimens examples
Body fluids (not listed for level 1)
Bone
Drainage from wounds
Feces
Sputum
Tissue
Level 3 specimens examples
Catheter tip
Urine
Tissue for quantitation
Level 4 specimens examples
Feces in preservative
Urine in preservative
Swabs in holding medium (aerobic and anaerobic)
What should be examined for evidence of barium in stool samples?
Stool should be examined for a chalky white color indicating barium presence.
What is the first step in gross examination of a specimen?
Locate areas with blood or mucus for culture and direct examination.
How should smears be prepared from swabs?
Roll the swab back and forth over contiguous areas of the glass slide to deposit a thin layer of sample material.
What should be prioritized if only one swab is available?
Culture should be prioritized over smear preparation.
How should smears be prepared from thick liquids or semisolids?
Immerse the swab in the specimen for several seconds and prepare a thin spread on the glass slide.
What should be done with opaque materials in smears?
Opaque materials must be thinly spread, and granules within the material should be crushed.
How should smears be prepared from thin fluids like urine and CSF?
Drop the specimen onto the slide without spreading.
What is the preferred method for preparing smears from bronchoalveolar lavage fluids?
Cytocentrifugation is preferred for this type of specimen.
What is the purpose of direct microscopic examination?
To assess the quality of the specimen, indicate the infectious process, guide routine culture workup, and dictate the need for nonroutine or additional testing.
How can sputum samples be assessed for quality?
By quantitating white blood cells and squamous epithelial cells present in the specimen.
What are the acceptable criteria for sputum samples for cultivation according to Bartlett’s criteria?
<10 epithelial cells and >25 pus cells per field.
What are the methods of direct examination?
- Gram Staining
- Acid Fast Staining (Ziehl-Neelsen, Kinyoun, and Fluorescent Method)
What is the process of homogenization in specimen processing?
Tissue grinding to prepare specimens for examination.
What does concentration in specimen processing involve?
Centrifugation or filtration of large volumes of sterile peritoneal or pleural fluids.
What is the purpose of decontamination in specimen processing?
To isolate bacteria from the specimen.
How should swab specimens be prepared for examination?
Vortex swabs in 0.5 to 1 ml of saline or broth for 10 to 20 seconds to dislodge material from fibers.
What should be done with biological fluids greater than 1 ml during processing?
Centrifuge for 20 minutes at 3,000 rpm.
