4 Specimen Collection And Processing Flashcards
Responsibilities of the lab practitioner
- Ensure that appropriate specimen management is performed
2. Recognize and reject suboptimal specimens
Macroscopic evaluation, odor
Microscopy inyerpretation
Preliminary report to physician
Isolation of pure cultures, antibiogram
ID, interpretation
Final report to physician
Best time to collect the specimen
Acute phase of infection
Before antibiotics are administered
How is the specimen transported??
Uses a container or transport medium to maintain viability of the organism and avoid hazards that result from leakage
Fundamentals of specimen collection
- If possible, collect the specimen in the acute phase of the infection and before antibiotics are administered
- Select the appropriate anatomic site for the collection of the specimen
- Collect the specimen using the proper technique and supplies with minimal contamination of the normal flora
- Package the specimen in a container or transport medium to maintain the viability of the organism and avoid hazards that result from leakage
- Label the specimen accurately with the specific anatomic site and patient information
- Transport the specimen to the lab promptly or make provisions to store the specimen in an environment that will not degrade suspected organism
- For patient -collected specimens clear instructions should be given by the authorizes healthcare personnel
- Notify the lab in advance if unusual pathogens are agents of bioterrorism are suspected.
Specimens used for bacteriological study
Abscess Blood Body fluids Csf Ear eye Foreign bodies GIT Genital tract Respiratory tract Urine
Lesion, wound pustule, ulcer
Preferably collected with the use of needle and syringe (aspirate) to enhance the recovery of anaerobic bacteria
Abscess
Swab along the leading edge of the wound
Aerobic swab moistened with stuart’s or amies medium
Superficial abscess
Aspirate from the wall of the abscess or the advancing margin of the lesion
Transferred to sterile tube or transport vial
Deep abscess
How is the blood collected for bacterial culture?
Venipuncture site should be disinfected with 70% alcohol and betadine for 30-60 seconds
Draw two sets from the right and left arms
Do not draw more than 3 sets in a 24hr period
When will you collect blood?
Febrile episode
Volume of blood to be collected?
20 ml/set- adults
5-10ml/set-children
1-2 ml-infants or neonates
What is the temperature need in the incubation of blood bottles?
37 degree celsius
What are the signs of microbial growth that in inspected twice a day?
- Floccular deposit on top of the blood layer
- uniform or surface turbidity
- Hemolysis
- Coagulation of the broth
- Surface pellicle
- Production of gas
- White grams on the surface or deep in the blood sugar
Signs that there is true infection
- The same organisms grows in two bottles of the same blood specimen
- The same organism grows from more than one specimen
- Growth is rapid (18 hrs)
- Different isolates of one species show the same biotypes and anti-microbial susceptibility profiles
Things to remember when collecting body fluids.
Disinfect skin before needle aspiration
Specimen concentration (centrifugation and filtration) may be required prior smearing and cultivation
Samples should be inoculated as soon as it is received
Rapid diagnosting testing for CSF
Gram stain
Required volume of CSF
5-10 ml
How do we store CSF?
35 degree celsius for 6 hours
How will you aspirate in the inner ear?
Ear canal should be cleaned with a mild soap solution before performing myringotomy
Aspirate material behind the eardrum
Use swab to collect material from ruptured eardrum
How is the specimen collected in the outer ear?
- The crust should be wiped off with a sterile saline
- Aerobic swab moistened with stuart’s or amies medium
- Swab should be firmly rotated in the outer canal to collect the sample.
How is the specimen collected in the conjunctiva?
- Aerobic swab moistened with stuart’s or amies mediumor premoistened with sterile saline may be utilized
- Samples should be obtained from both eye with two separate swabs
Collection of corneal scrapings?
Administer first local anesthetic before collecting the specimen
What species is detected in IUD?
Actinomyces spp
Collection of foreign bodies in catheters?
3-7 segment is rolled 4x across the agar
Moe than 15 colonies are required to perform ID and susceptibility tests
Best specimen for infants?
Gastric aspirate
Used for the examination of AFB
Should be collected early in the morning before the patient rises from the bed or takes his/her first meal
Must be neutralized within one hour of collection
Gastric aspirate
Recommended for the detection of H. pylori
Gastric biopsy
2.5 cm swab is inserted through the anal sphincter
Rectal swab
Specimen pf choice for detecting GI pathogens
Stool culture
- If patient has received antiparasitic drugs the specimen, collection should be done after 7-10 days
Collection of vaginal swab?
- Exudates should be removed before specimen collection
2. Swab (moistened with Stuart’s or Amies) the secretions from the mucous membranes of the vagina
Collection of spx in prostate gland
Gland should be cleaned with soap and water
Secretions on the swab (moistened with Stuart’s or Amies) or in the tube should be collected.
Appropriately used for lower respiratory tract if a sheathed or protected catheter?
Anaerobic culture
Collection of sputum?
- Px should rinse his/her mouth with sterile water prior collection
- Should be collected through deep cough or aerosol-induced for pediatrics or uncooperative Px
Type of sputum preferred for acid fast stains
First morning specimen
Reject the spx if?
Gram stain reveals <25 WBC and >10 epithelial cells/lpf are seen
Specimen of chouce for B. pertussis
Upper tract (nasopharyngeal)
Upper tract (nasopharyngeal) collection
Flexible swab is inserted through the nose into the posterior nasopharynx and rotated for 5 seconds
Recommended specimen for routine culture of GroupA strep
Upper tract (pharyngeal)
Collection of upper tract (pharyngeal)
Posterior pharynx and tonsils should be swabbed
Preferred specimen in urine
Clean catch midstream voided, first morning
Improper collection of urin
Presence of 3 or more different organisms in culture
True infection in urine by a pure of E. coli?
> 10^5 CFU/ml
More than 10^5 CFU per ml
Category 3
Int: strongly suggestive of UTI
Fewer than 10^4 per ml
Category 1
Int: probable absence of uTi
10^4 to 10^5 CFU per ml
Category 2
Int: if asymptomatic, request for another specimen and repeat the count
The first 15ml of the urine should be boided or expelled by the bladder before collecting ensuring urinary system as spx
Straight catheter
5ml to 10ml urine should be aspirated with needle and syringe
Indwelling catheter (foley)
Uses a needle for aspirating on the area above the symphysis pubis through the abdominal wall into the full bladder
Suprapubic aspirate
Uses a specific type of blotting paper and should measure 7.5 cm long by 0.6 cm wide and marked at 1.2 cm from one end
Filter paper di-strip method
What is preferred swabs for stool spx?
Dacron or calcium alginate swabs
Ideal specimen transport?
Within 30 mins of collection and not longer than 2 hrs
Ideal transport cor anaerobic bacteria?
Not take more than 10 mins
Ideal transport of CSF
Within 15 mins at RT
Ideal transport of blood or bm?
Within 2hrs at room temp
Transport of grastric biopsy?
Immediately at 4 degree celsius
Transport condition of body fluids, bone, inner ear, corneal scrapings, foreign bodies, gastric aspirate, suprapubic aspirate of urine, prostatic sample
Immediately at room temp
Transport condition for abscess, outer ear, conjunctiva specimen, genital tract specimen, hair, nail or skin scrapings, respiratory tract specimen, tissue specimen
Within 24hrs at RT
Transport condition of Indwelling and straight catheter
Within 2hrs at 4 degree celsius
Rectal swab, stool culture, clean voided midstream urine
Within 24 hrs at 4 degree celsius
Preservative of urine
Boric acid
Preservative for stool
Refrigerated
What to do when stool is delayed for longer than 2 hrs?
Add to Cary-Blair transport medium
What specimen is collected withoutpreservative and can be refrigerated?
Clostridium difficile
Holding media?
It maintains the viability of mocroorganisms present in a specimen but do nit allow their multiplication
Transport media
Added to transport media to absorb fatty acids present in the specimens?
Charcoal
What fastidious organisms can be killed by the charcoal?
N. gonorrhoeae
B. pertussis
Transport media?
Stuart’s medium Amies medium Cary Blair transport medium Transgrow JEMBEC
Stuart transport medium color?
Red
Amies transport medium color
Blue
Cary blair transport medium color?
White
Function of 0.025% sodium polyanethol sulfonate (SPS)
- To inhibit phagocytosis and complement activation
- To neutralize aminoglycoside antibiotics
- To neutralize the bactericidal effect of plasma
How many days dows C. difficule is stored?
3
Where can we strore urine, stool, sputum, swabs and viral specimens?
Refrigerator (4 degree celsius)
Note!!!
Specimens that are suspected of containing anaerobic bacteria should never be refrigerated.
Recommended for CSF samples intended for gram staining culture and sensitivity testing
Incubator (35 degree celsius)
Temp required for anaerobic culture, sterile body fluids, genital specimens and swabs for ear and eye
RT (22-25 degree celsius)
Temp for sera that is used for serological studies?
Freezer (-20 degree celsius)
Tenp for tissues or specimens that are to be stored for a long time
Alao used for the study of C. difficile
Freezer (-70 degree celsius)
Stprage conditions:
A. Body fluids, bone spx, gastric biopsy, suprapubic aspirate, prostate
B. Inner ear
C. Abscess, outer ear, eye and conjuctiva, URT, tissues
D. Hair, nail, or skin scrapings
A. Plate ASAP
B. 6 hrs at RT
C. 24 hrs at RT
D. Indefinitely at RT
Storage conditions: A. Blood, , corneal, urethral in JEMBEC B. CSF C. Lower respiratory tract, clean voided midstream urine, catheter, urine, foreign bodies D. Rectal swab, stool culture
A. Immediately at 35 degree celsius
B. 6 hrs at 35 degree celsius
C. 24 hrs at 4 degree celsius
D. 72 hrs at 4 degree celsius
Specimen rejection?
- The information on the label does not match the information on the requisition or the specimen is not labeled at all
- Improper transport temp and medium
- Insufficient quantity
- Leakage
- Transport time exceeds 2 hrs post collection or specimen is not preserved
- Specimen is in a fixative (formalin)
- Specimen is dried
- Specimen has been received for anaerobic culture from a site known to have anaerobes as part of the normal flora
- More than one specimen from the same source except blood and from the same patient on the same day.
- Single swab submitted with multiple request for various organisms
- Expectorated sputum in which gram stain reveals <25 WBCs and > 10 epithelial cells/lpf
Level or spx prioritization that requires quantitation
Catheter tip, urine, tissue for quantitation
Level 3
Level or spx prioritization that may quickly degrade or have growth of contaminating flora
Unprotected or unpreserved
Body fluids not listed in level 1, bone, drainage from wounds, feces, sputum, tissue
Level 2
Level or spx prioritization that is classified as critical
Represents a potentially life- threatening illness and are from an invasive source
Amniotic fluid, brain, CSF, heart valves, pericardial fluid
Level 1
Level or spx prioritization that arrive in the lab in holding or transport media
Processing may be delayed to prioritize s more critical nature first
Feces and urine in preservative, swabs in holding medium (aerobic or anaerobic)
Level 4
Critical (panic) results
- gram stain and culture
- Gram stain suggestive of C. perfringens
- AFB stain
- +blood culture
- Presence of S. pyogenes in surgical wound
- Positive antibiotic resistant bacteria
- Positive for Legionella. Francisella and Brucella
