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Questions and Answers

What is the correct purpose of barcoding in specimen collection?

  • To provide a detailed log of laboratory processes
  • To identify the patient visually during collection
  • To ensure specimens are transported without damage
  • To prevent mistakes in specimen identification and tracking (correct)
  • Which preservative is specifically recommended for accurate colony counts in urine?

  • Boric acid (correct)
  • Schaudinn's fluid
  • Formalin
  • Phosphate buffered saline (PBS)
  • Which statement regarding refrigeration and freezing of specimens is accurate?

  • Both methods have the same effect on microorganisms.
  • Freezing is preferable to slow down microbial growth.
  • Refrigeration can kill certain bacteria during storage.
  • Refrigeration helps to slow down microbial growth. (correct)
  • What is the role of anticoagulants in sample collection?

    <p>To prevent the clotting of samples while preserving microbes</p> Signup and view all the answers

    In labeling specimens, which information is NOT required?

    <p>Patient's insurance information</p> Signup and view all the answers

    Which of the following organisms is classified as fragile?

    <p>Streptococcus pneumoniae</p> Signup and view all the answers

    What is a key characteristic of formalin as a preservative?

    <p>It preserves trophozoites and cysts in stool samples.</p> Signup and view all the answers

    Why is it critical for laboratory staff to be informed about specimen collection in advance?

    <p>To ensure appropriate materials and instructions can be provided</p> Signup and view all the answers

    What characteristic distinguishes Mycobacterium from Gram-positive bacteria?

    <p>Presence of mycolic acid in the cell wall</p> Signup and view all the answers

    Which Bacillus species is primarily known for causing anthrax?

    <p>Bacillus anthracis</p> Signup and view all the answers

    What is the main function of Bacillus stearothermophilus spores in laboratory settings?

    <p>To test autoclave efficiency</p> Signup and view all the answers

    Which of the following pairs of Bacillus species are considered laboratory contaminants?

    <p>Bacillus subtilis and Bacillus licheniformis</p> Signup and view all the answers

    What physical characteristics do Bacillus species typically exhibit?

    <p>Gram positive rods arranged in pairs or chains</p> Signup and view all the answers

    Which of the following groups of Bacillus species produce spores that do not distend the sporangium?

    <p>Large cell subgroup</p> Signup and view all the answers

    Which Bacillus species is utilized in genetically modified crops for pest resistance?

    <p>Bacillus thuringiensis var. israelensis</p> Signup and view all the answers

    What is a unique feature of Bacillus endospores?

    <p>They are oval or sometimes round or cylindrical</p> Signup and view all the answers

    Which Gram staining characteristic is associated with Corynebacterium species?

    <p>Gram-positive non-spore forming bacilli appearing with Chinese characters</p> Signup and view all the answers

    What is the significance of Loeffler’s methylene blue in identifying Corynebacterium?

    <p>It highlights the metachromatic granules made of polyphosphates.</p> Signup and view all the answers

    What type of hemolysis is observed in some Corynebacterium species on sheep blood agar?

    <p>Variable hemolysis with enhanced degrees</p> Signup and view all the answers

    Which of the following tests is NOT one of the four preliminary tests for identifying Corynebacterium species?

    <p>Oxidase test</p> Signup and view all the answers

    What distinguishes C.pseudotuberculosis biovar equi from biovar ovis in nitrate reduction?

    <p>Biovar equi reduces nitrate, while biovar ovis fails to do so.</p> Signup and view all the answers

    Which containment level is recommended for handling C.diphtheriae and C.ulcerans?

    <p>Containment Level 3</p> Signup and view all the answers

    What is the main effect of untreated TB disease?

    <p>It can be fatal if not treated properly.</p> Signup and view all the answers

    What must be considered when performing laboratory procedures that can generate infectious aerosols?

    <p>Use a microbiological safety cabinet.</p> Signup and view all the answers

    Which of the following statements accurately describes Bacillus anthracis?

    <p>It is sensitive to penicillin.</p> Signup and view all the answers

    What is a notable characteristic that differentiates Bacillus anthracis from other Bacillus species?

    <p>It is non-haemolytic.</p> Signup and view all the answers

    What kind of spores do Bacillus species typically produce?

    <p>Centrally located in unswollen sporangia.</p> Signup and view all the answers

    Which Bacillus species is incorrectly categorized based on its haemolytic properties?

    <p>Bacillus anthracis</p> Signup and view all the answers

    At what temperature does Bacillus anthracis grow optimally?

    <p>37°C</p> Signup and view all the answers

    What statement about the spore formation of Bacillus anthracis is true?

    <p>Spores do not form in host tissues unless exposed to air.</p> Signup and view all the answers

    Which genus has had a taxonomic development including Bacillus species?

    <p>Bacillus</p> Signup and view all the answers

    Bacillus species that are described as oxidase positive can lead to confusion with which other bacteria?

    <p>Pseudomonas species</p> Signup and view all the answers

    What is the primary reason for performing the catalase test on colonies from TSA instead of BAP?

    <p>BAP can produce false positive results due to rbcs.</p> Signup and view all the answers

    Which specimen type is NOT suitable for culturing meningococci?

    <p>Skin swab</p> Signup and view all the answers

    In which Gram-positive genus are spores located toward the end of the cells?

    <p>Clostridium</p> Signup and view all the answers

    Which group of bacteria is primarily associated with anaerobic cultivation?

    <p>Clostridium</p> Signup and view all the answers

    What is the least common specimen type to be tested for enterics and Vibrio?

    <p>Throat swabs</p> Signup and view all the answers

    Which of the following organisms is NOT included in the Gram-negative coccobacilli grouping?

    <p>Streptococcus</p> Signup and view all the answers

    What is a characteristic feature of spirochetes that makes them difficult to Gram-stain?

    <p>They lack a cell wall.</p> Signup and view all the answers

    Which Gram-negative bacilli group includes organisms associated with foodborne illnesses?

    <p>Enterobacteriaceae</p> Signup and view all the answers

    Study Notes

    Specimen Collection and Transport

    • Bacteriology Laboratory must be informed prior to specimen collection for preparation of necessary materials and instructions for MLS/MT.

    Labelling Protocol

    • Critical that patients provide their full name; if unable, guards must state the name.
    • Include essential details: age, sex (Male/Female), in-patient/out-patient status, and date of collection.
    • Barcoding is employed to ensure accurate identification of specimens; bar codes placed on containers—not caps—to prevent mix-ups.
    • Bar codes linked to bacteriology worksheets upon specimen processing to maintain traceability.

    Use of Preservatives

    • Boric acid utilized for reliable colony counts in urine samples.
    • Phosphate buffered saline preserves fecal samples to prevent bacterial death (e.g., Shigella).
    • Formalin, polyvinyl alcohol, and Schaudinn's fluid used to maintain viability of trophozoites and cysts in stool specimens.

    Anticoagulants in Specimen Collection

    • Anticoagulants prevent blood clotting while preserving microorganisms.
    • Sodium polyanethol sulfonate (0.025% w/v) is preferred for blood specimens.
    • Heparin inhibits Gram-positive bacteria; alternatives include citrate and EDTA.

    Refrigeration vs. Freezing of Specimens

    • Refrigeration is favored as it slows microorganism growth, whereas freezing can be lethal to bacteria.

    Organism Classification

    • Fragile Organisms: Examples include Streptococcus pneumoniae, Neisseria species, and anaerobes.
    • Bacillus Characteristics: Notable for their endospore formation and Gram-positive rod structure.
    • Gram-Negative Organisms: Diverse group including enterics (e.g., Escherichia, Salmonella) and vibrio.

    Bacillus Species Overview

    • Genera includes 268 species, medically significant ones being Bacillus anthracis (causes anthrax) and Bacillus cereus (causes foodborne illness).
    • Bacillus subtilis is a common lab contaminant; B. thuringiensis is used in GMO crops.

    Characteristics of Bacillus

    • Endospores typical of Bacillus are resistant to harsh conditions.
    • Division based on spore morphology: Group 1 (smooth spores), Group 2 (variable spores), Group 3 (swollen sporangia).
    • Many species exhibit hemolytic activity, whereas B. anthracis is non-hemolytic.

    Anthrax Detection

    • B. anthracis is sensitive to penicillin and requires direct referral to reference labs if suspected.
    • Characteristic colonies on BAP appear gray/white with a “bee’s eye” look and irregular, tacky edges.

    Corynebacterium Species Insights

    • C. diphtheriae and related species categorized as Hazard Group 2, necessitating safety precautions in labs.
    • Identification methods include nitrate and urease testing, with hemolysis on different media affecting test outcomes.
    • Diphtheria antitoxin available for treatment of clinical cases, with strict controls around handling specimens.

    Mycobacterium Overview

    • Mycobacterium tuberculosis is the causative agent of Tuberculosis (TB), impacting lungs and other body parts.
    • Distinction between latent TB infection (LTBI) and TB disease essential for treatment considerations.

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