Podcast
Questions and Answers
What is the primary purpose of performing a blood culture?
What is the primary purpose of performing a blood culture?
- To assess throat infections
- To identify stool pathogens
- To detect cases of meningitis
- To rule out bacteremia or sepsis (correct)
What is the main advantage of Gram staining?
What is the main advantage of Gram staining?
- It identifies acid-fast bacilli exclusively
- It highlights all bacteria in a sample
- It detects fungi in specimens
- It differentiates between gram positive and gram negative organisms (correct)
Before staining a specimen, what is the first step that must be taken?
Before staining a specimen, what is the first step that must be taken?
- Perform a urine culture
- Make a bacterial smear (correct)
- Inoculate agar plates
- Prepare a throat swab
Which type of specimen processing is specifically performed to detect Mycobacterium?
Which type of specimen processing is specifically performed to detect Mycobacterium?
Which family of pathogens is specifically monitored during stool processing?
Which family of pathogens is specifically monitored during stool processing?
Which of the following organisms cannot be classified as Gram positive based on the given content?
Which of the following organisms cannot be classified as Gram positive based on the given content?
What distinguishes Acid Fast organisms from Non-Acid-Fast organisms?
What distinguishes Acid Fast organisms from Non-Acid-Fast organisms?
Which of the following is NOT classified as an Acid Fast organism?
Which of the following is NOT classified as an Acid Fast organism?
Which of the following organisms would likely appear as Gram negative based on the information provided?
Which of the following organisms would likely appear as Gram negative based on the information provided?
Which type of organisms may substitute for Malachite Green during staining?
Which type of organisms may substitute for Malachite Green during staining?
Which of the following is classified as a solid medium?
Which of the following is classified as a solid medium?
What is the purpose of transport media?
What is the purpose of transport media?
Which medium is specifically designed for biochemical testing?
Which medium is specifically designed for biochemical testing?
Which of the following is considered a general purpose medium?
Which of the following is considered a general purpose medium?
What type of agar is used for susceptibility testing?
What type of agar is used for susceptibility testing?
Which type of media is characterized by a liquefiable solidifying agent?
Which type of media is characterized by a liquefiable solidifying agent?
Which medium allows for the detection of motility in bacteria?
Which medium allows for the detection of motility in bacteria?
What characteristic defines semi-solid media?
What characteristic defines semi-solid media?
What primary virulence factor is associated with Neisseria gonorrhoeae?
What primary virulence factor is associated with Neisseria gonorrhoeae?
Which of the following describes the appearance of Bacillus anthracis colonies?
Which of the following describes the appearance of Bacillus anthracis colonies?
Which test is positive for Neisseria meningitidis and indicates its capsule presence?
Which test is positive for Neisseria meningitidis and indicates its capsule presence?
What condition can be caused by Neisseria gonorrhoeae in newborns?
What condition can be caused by Neisseria gonorrhoeae in newborns?
Which of the following swabs is NOT recommended for collecting samples for Neisseria gonorrhoeae?
Which of the following swabs is NOT recommended for collecting samples for Neisseria gonorrhoeae?
What characteristic differentiates Bacillus anthracis from other Bacillus species?
What characteristic differentiates Bacillus anthracis from other Bacillus species?
Which of the following is a natural habitat for Neisseria meningitidis?
Which of the following is a natural habitat for Neisseria meningitidis?
What type of hemolysis is produced by the genus Bacillus on Blood Agar Plates (BAP)?
What type of hemolysis is produced by the genus Bacillus on Blood Agar Plates (BAP)?
Which of the following treatments is used to prevent Ophthalmia neonatorum?
Which of the following treatments is used to prevent Ophthalmia neonatorum?
Which of the following is NOT a characteristic of Bacillus anthracis colonies?
Which of the following is NOT a characteristic of Bacillus anthracis colonies?
What is the characteristic appearance of colonies on Tinsdale medium when culturing C. diphtheriae?
What is the characteristic appearance of colonies on Tinsdale medium when culturing C. diphtheriae?
Which guinea pig model is protected against diphtheria toxin?
Which guinea pig model is protected against diphtheria toxin?
What primary infection site is associated with diphtheria?
What primary infection site is associated with diphtheria?
In which test is the presence of diphtheria toxin detected to determine immunization status?
In which test is the presence of diphtheria toxin detected to determine immunization status?
What is the primary virulence factor responsible for the symptoms associated with C. diphtheriae?
What is the primary virulence factor responsible for the symptoms associated with C. diphtheriae?
Which isolation medium is primarily used for the selective growth of C. diphtheriae?
Which isolation medium is primarily used for the selective growth of C. diphtheriae?
What is the result of injecting a non-protected guinea pig with diphtheria toxin?
What is the result of injecting a non-protected guinea pig with diphtheria toxin?
What is the incubation temperature and duration for culturing C. diphtheriae on selective media?
What is the incubation temperature and duration for culturing C. diphtheriae on selective media?
Flashcards
Gram Staining
Gram Staining
A staining technique that differentiates bacteria based on their cell wall structure. Gram-positive bacteria retain the crystal violet dye and appear purple, while Gram-negative bacteria do not retain the dye and appear pink after a counterstain.
Acid-Fast Bacilli (AFB) Staining
Acid-Fast Bacilli (AFB) Staining
A staining method that identifies acid-fast bacilli, which have mycolic acid in their cell walls. These bacteria resist decolorization with acid alcohol and retain the primary stain.
Blood Culture
Blood Culture
A test used to detect the presence of bacteria in the blood, indicating bacteremia or sepsis.
CSF Processing
CSF Processing
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Sputum Processing
Sputum Processing
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Stool Processing
Stool Processing
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Urine Culture
Urine Culture
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Throat Swabs
Throat Swabs
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Nasopharyngeal Swabs
Nasopharyngeal Swabs
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Neisseria
Neisseria
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Neisseria gonorrhoeae
Neisseria gonorrhoeae
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Neisseria meningitidis
Neisseria meningitidis
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Moraxella catarrhalis
Moraxella catarrhalis
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Corynebacterium diphtheriae
Corynebacterium diphtheriae
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Bacillus anthracis
Bacillus anthracis
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Liquid Media (Broth)
Liquid Media (Broth)
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Semi-solid Media
Semi-solid Media
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Solid Media (Agar)
Solid Media (Agar)
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Liquefiable solid media
Liquefiable solid media
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Non-liquefiable solid media
Non-liquefiable solid media
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Transport Media
Transport Media
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Biochemical test media
Biochemical test media
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Media for Susceptibility Test
Media for Susceptibility Test
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Motility test medium
Motility test medium
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Crystal Violet
Crystal Violet
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Safranin
Safranin
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Gram-positive bacteria
Gram-positive bacteria
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Gram-negative bacteria
Gram-negative bacteria
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Mycolic acid
Mycolic acid
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Guinea Pig A (Protected) – Inject Anti-diphtheria toxin
Guinea Pig A (Protected) – Inject Anti-diphtheria toxin
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Guinea Pig B (Unprotected) – No anti-toxin
Guinea Pig B (Unprotected) – No anti-toxin
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Shick’s Test
Shick’s Test
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VERO cell cytotoxicity assay
VERO cell cytotoxicity assay
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Study Notes
Gram Staining
- Differentiates between Gram-positive and Gram-negative bacteria
- Primary stain is Crystal Violet
- Gram-positive bacteria retain the violet dye, appearing purple
- Gram-negative bacteria do not retain the violet dye, appear pink after a counterstain (e.g., Safranin)
Acid-Fast Bacilli (AFB) Staining
- Distinguishes acid-fast bacilli from non-acid-fast bacilli
- Acid-fast bacilli contain mycolic acid in their cell walls, making them difficult to decolorize
- Used to identify bacteria like Mycobacterium tuberculosis
Purposes of Testing Specimen
- Blood culture: Detects bacteremia or sepsis
- CSF processing: Detects meningitis
- Sputum processing: Detects Mycobacterium
- Stool processing: To detect gastrointestinal pathogens, especially from the Enterobacteriaceae family
- Urine culture: Detects urinary tract infections
- Throat swabs: Detects pharyngitis caused by Streptococcus pyogenes
- Nasopharyngeal swabs: Detects Bordetella, Haemophilus influenzae, and carriers of Neisseria
Gram Staining: Positive and Negative Organisms
- Gram-positive:
- Clostridium
- Bacillus
- Erysipelothrix
- Lactobacillus
- Listeria
- Gram-negative:
- Rickettsia
- Chlamydia
- Mycoplasma
- Ureaplasma
- Spirochetes
Types of Media
- Liquid Media (broth):
- Tryptic Soy Broth (TSB)
- Peptone Water
- Brain Heart Infusion (BHI)
- Semi-solid Media:
- SIM (Sulfur, Indole, Motility) medium
- Solid Media (agar):
- EMB (Eosin Methylene Blue)
- MSA (Mannitol Salt Agar)
- Rice medium
- HBT (Hektoen Enteric Agar)
- Liquefiable solid media:
- EMB, MSA
- Non-liquefiable solid media:
- Simon Citrate
- Lysine Iron Agar (LIA)
- Urea agar
- Transport Media:
- JEMBEC
- Cary Blair (Vibrio spp.)
- Transgrow (Neisseria)
- Amies
- Biochemical test media:
- Simon Citrate
- Lysine Iron Agar (LIA)
- Urea agar
- Media for Susceptibility Test:
- Mueller-Hinton Agar (MHA)
- Motility test medium:
- SIM (Sulfur, Indole, Motility)
Neisseria, a Genus of Bacteria
- Neisseria gonorrhoeae:
- Causes gonorrhea
- Primary virulence factor: pili
- Ferments glucose
- Neisseria meningitidis:
- Causes meningitis
- Primary virulence factor: capsule
- Neufeld Quellung test positive
- Ferments glucose and maltose
- Can be normal flora
Moraxella Catarrhalis
- Normal flora
- Causative agent of otitis media (ear infections)
Corynebacterium Diphtheriae
- Produces diphtheria toxin
- Causes diphtheria
- Characteristic symptom: Pseudomembrane formation
- Can be differentiated from other Bacillus species by its non-motile and gamma hemolytic characteristics
Bacillus Anthracis
- Forms "disjointed bamboo fishing rod appearance" with square ends
- Colonies have a tenacious, sticky consistency
- Lifted colonies stand like beaten egg white
- Colonies may have swirling projections, appearing like a Medusa head or lion head
- Shows a string of pearls pattern
- Colonies have a comet tail appearance
- Colonies have a cut-glass or frosted glass appearance
- Forms inverted fir tree/pine tree appearance in gelatin media
Diagnostic Methods
- Loeffler’s serum and PAI’s coagulated egg:
- Stimulate granule formation and pleomorphism
- **CTBA (cystine tellurite blood agar): **
- Primary isolation media
- Selective media
- Tinsdale medium:
- Black colonies with a brown halo
- Guinea Pig A (Protected) – Inject Anti-diphtheria toxin:
- Used to determine if an animal is immune/susceptible to diphtheria
- Guinea Pig B (Unprotected) – No anti-toxin:
- Used to determine if an animal is immune/susceptible to diphtheria
- Shick’s Test:
- Immunity/susceptibility test for diphtheria
- Detects risk of diphtheria
- VERO cell cytotoxicity assay: - Gold standard for diphtheria toxin production
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Description
Test your knowledge on key microbiology staining techniques, including Gram staining and Acid-Fast Bacilli (AFB) staining. This quiz covers the differentiation of bacteria types and various specimen testing purposes crucial for identifying infections. Perfect for students in microbiology courses!
