(P) Lec 5: Collection, Handling, and Processing Of Specimen Flashcards
All parts of the body exposed to the outside environment is inhabited by the
____ and specimens coming from these parts are considered ____.
Normal Microbiota
Non-sterile
Consists of non-pathogenic organisms but can be pathogenic once placed outside their normal habitat
Normal Micriobiota
Formerly known as normal flora
Specimens coming from body parts not exposed to the outside environment
Sterile Specimens
Sterile or Non-sterile Specimen?
✦ Cerebrospinal Fluid (CSF)
✦ Peritoneal Fluid
✦ Pericardial Fluid
✦ Pleural Fluid
✦ Blood
✦ Suprapubic Aspirate (SPA)
Sterile
Sterile Specimens
When cultured under normal conditions, there should be ____
no growth of microorganisms (absolutely negative)
Specimens coming from body parts exposed to the outside environment
Non-sterile Specimen
Sterile or Non-sterile Specimen?
✦ Urine
✦ Stool
✦ Sputum
Non-sterile
Normally, urine is ____ in the bladder
sterile
Collection via ____ is critical because there might be a possibility of contamination when performed incorrectly
midstream clean-catch
When is urine considered sterile?
When collected via suprapubic aspiration
What do MDs usually request prior to antibiotic therapy?
Culture & Sensitivity
Unless the objective is to monitor the treatment
Why is sepsis and exception to requesting C&S prior to antibiotic therapy?
Because administration of first line antimicrobials cannot be delayed
In automated blood culture machines, they have?
Antimicrobial Removing Device (ARD)
Blood C&S with ARD (antibiotic is already given but C&S is still requested)
In aseptic collections and sterile containers, there should be no ____
Contaminants
In microbiology, ____ will do except for blood culture
minimal amounts
In microbiology, minimal amounts will do except for ____
blood culture
This is to obtain a higher yield of isolates
Acute Stage of the Disease Process
Ideal TAT
Processed immediately after collection
Ideal TAT for critical specimens (coming from sterile site)
Within 15 mins after collection
Ideal TAT for non-critical (other) specimens
within 2 hours after collection
When processing, we should prioritize what type of specimen?
Critical
What should you process first?
Stool vs. Urine vs. Blood vs. CSF
Blood then CSF
If you are considering that the sample contains
microorganisms that are sensitive to drying, you should process them ____
immediately
Collection Methods
Suitable and done ONLY for aerobic organisms
Because the collection method is already exposed to oxygen
Cotton Swab (Swab Technique)
Advantage of cotton swab technique?
Common, easily available, easy to perform
Disadvantage of cotton swab technique?
Toxic to other organisms
If you are suspecting that the isolate is ____ (also sensitive to drying), note that cotton contains fatty acids that are toxic to the organism
Neisseria gonorrhoea
If there is no other choice besides cotton, what can you do when the isolate is Neisseria gonorrhoea?
Add charcoal so as to neutralize the toxic fatty acids present in the cotton
✦ Made of synthetic fiber, not cotton
✦ Highly absorbent, so the sample will not easily dry out
Rayon and Dacron Technique
Disadvantage of Rayon and Dacron?
Expensive and may not be readily available
◦ Any extraction can support the growth of aerobic and anaerobic culture, simply because
the method does not allow exposure of the specimen to oxygen
◦ Aerobic and anaerobic culture
◦ Ex: Peritoneal fluid, urine via SPA, wound exudate, blood
Needle Aspiration/Extraction
Done by aspirating from a catheter tube
Catheterization
Diagnostic Purpose of Blood Specimen
To determine bloodstream infection (bacteremia)
What can be determined during blood culture?
Presence of bacteria, not the toxin
Usual order of blood specimen
2 sets of blood culture (1 for aerobic bottle and 1 for anaerobic bottle)
Why do they order 2 sets of blood culture?
To distinguish TRUE pathogen
Media for manual blood culture
Brain-Heart Infusion Broth (BHIB) with 0.025% Sodium Polyanethole Sulfonate (SPS) (+/- 1% Gelatin)
Best anticoagulant for blood culture despite it being able inhibit some microorganisms
SPS
Why SPS regarded as the best anticoagulant for blood culture?
because of its anticomplement and
antiphagocytic properties; it also neutralizes aminoglycosides
Anticoagulant-to-Blood Ratio for Adults
1:10
Anticoagulant-to-Blood Ratio for Children
1:5
Positive result indicators for manual blood culture
Hemolysis, Turbidity, Pellicle Formation, Bubble Formation
Preliminary / Initial Reporting of Results
after 24 hrs, 48 hrs, 72 hrs, 5 days, 7 days
When the spx tested negative after 24 hours,
the initial report would be negative
When the spx tested positive after 48 hours,
subculture is performed
Official report on the isolate is released usually ___
after another 3 days (5th day)
The final result would be released at the ___
7th day
T or F: When spx tested positive in a time frame, you do not have to perform a subculture
F (you have to)
If you see this, study how to do the subculture hehe
Go bebi !!
TAT for Typhoid Fever
7 days
TAT for Brucellosis and Endocarditis secondary to HACEK species
21 days
What are the HACEK species?
Haemophilus
Aggregatobacter
Cardiobacter
Eikenella
Kingella kingae
These organisms associated with bacterial endocarditis are slow-growers
HACEK
Principle of Automated Blood Culture
Fluorescence-based
TAT of Automated Blood Culture
5 days
- Normally sterile (inside the bladder)
- Depending on how it is collected, it can be sterile or nonsterile
Urine Specimen
Collection Methods for urine specimens
Midstream Clean-Catch
Catheterized
Suprapubic Aspiration
Diagnostic Purpose of urine specimen
Diagnosis of UTI
T or F: Only in urine culture that we perform quantitation
T
Give the formula of CFU
CFU = # of Colonies x Loop Factor (calibrated wire loop)
Loop Factors
▪︎ 0.1 mL - 10
▪︎ 0.01 mL - 100
▪︎ 0.001 mL - 1000
Urine Specimen
When is the interpretation for >100,000 CFU/mL?
Significant
Urine Specimen
When is the interpretation for < 50,000 CFU/mL?
Negative
Urine Specimen
When is the interpretation for Between 50,000 and 100,000 CFU/mL?
Borderline or Indeterminate
What happens when the urine specimen falls as borderline or indeterminate?
You will need to repeat urine culture
Critical and sterile Specimen and collected via Lumbar Puncture
CSF Specimen
Diagnostic Purpose for CSF specimen
For the diagnosis of Bacterial Meningitis
Media for CSF specimens
BAP, CAP, MAC
CSF is incubated at what temperature?
Room Temperature or Body Temperature
- Polymicrobial in nature; allows isolation of several microorganisms
- Collected through swabs or aspirations
- Emits foul odor due to Anaerobes and Facultative Anaerobes (most pathogenic organisms)
Wound discharge/abscess specimen
Media for Wound discharge/abscess specimens
◦ Plating through MAC and BAP
◦ Thioglycollate (Liquid Media)
Which media of wound discharge/abscess specimen is this?
✦ Enrichment Broth
✦ Allows the growth of Obligate Aerobes, Facultative Anaerobes, and Microaerophilics
Thioglycollate (Liquid Media)
- Contain many enteric organisms (contaminated with normal microbiota)
- Gram stain is NOT usually done (very seldom, simply because the fecal matter is full of gramnegative organisms)
Stool specimen
What selective and differential media are being used for stool specimen?
✦ MAC - MacConkey Agar
✦ HEA - Hektoen Enteric Agar
✦ EMB - Eosin-Methylene Blue Agar
Differential selective media for isolation of Salmonella spp.
SSA (Salmonella-Shigella Agar), Selenite F Broth
Differential selective media for isolation of Vibrio spp.
TCBS (Thiosulfate-Citrate-Bile Salts-Sucrose Agar) and Peptone Water
Includes nasopharyngeal swabs, sputum, bronchial and tracheal aspirate, and nasopharyngeal aspirates
Respiratory specimens
Respiratory specimens
Gold standard for decontamination
Sodium hydroxide
Respiratory specimen
Gold standard for digestion
N-acteyllcysteine (NaLC)
Plating media for respiratory specimens
BAP, MAC, CAP
Diagnostic purpose for throat swabs
Strep Throat, Diptheria, Neisseria infection
Plating media for throat swabs
BAP, CAP
Plating media for Neisseria spp.
Modified Thayer Martin Media
- Do Gram Stain (to check for the intracellular presence of Gram-negative coccobacilli)
Vaginal, Urethral & Rectal Swabs
Media for Vaginal, Urethral & Rectal Swabs
CAP
BAP
MTMM (if infection with Neisseria gonorrhoeae is suspected)
How many sputum specimen is required for TB culture?
Three (1 for culture, 2 for acid-fast staining)
Gold standard for TB Culture
NaOH (decontamination) and NaLC (digestion)
Media for TB Culture
◦ Löwenstein-Jensen (LJ) Medium
◦ Middlebrook 7H11/7H10
◦ BACTEC
◦ Gene Xpert
This can detect the presence of Mycobacterium tuberculosis in the specimen and determine whether the isolate is Multidrug Resistant
Gene Xpert
Check niyo table summary ni Wakin and tell him thank you <3
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