Microbiology Quiz: Streptococcus and Proteus Species
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Questions and Answers

What defines the Lancefield groups of streptococci?

  • The type of enzymes they produce
  • The size of the bacterial colonies
  • The methods of antimicrobial resistance
  • The specific carbohydrates in their cell wall (correct)

    • Which specimen is typically used for diagnosing pharyngitis caused by S.pyogenes?

  • Blood for serology
  • Wound culture
  • Throat swab (correct)
  • Skin secretion

    • For which type of infection is a throat swab NOT typically collected?

  • Skin infections
  • Pharyngitis
  • Post-streptococcal diseases
  • Erysipelas (correct)

    • What type of specimen is required for post-streptococcal diseases?

    <p>Blood for serology</p> Signup and view all the answers

    Which of the following infections is not typically associated with S.pyogenes?

    <p>Bacterial pneumonia</p> Signup and view all the answers

    What type of colonies are observed in Proteus species on culture media containing selective agents?

    <p>S colonies</p> Signup and view all the answers

    Which of the following biochemical patterns is characteristic of Proteus mirabilis?

    <p>Urease positive</p> Signup and view all the answers

    On which type of agar does Proteus mirabilis grow and produce swarming colonies?

    <p>Blood agar plate</p> Signup and view all the answers

    Which of the following statements about Proteus species is incorrect?

    <p>They can ferment lactose.</p> Signup and view all the answers

    What is a common characteristic of colonies formed by Proteus species on lactose-containing media?

    <p>Lactose-negative colonies</p> Signup and view all the answers

    What specimens can be used to culture Klebsiella species?

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

    What is the result of a Gram stain for Klebsiella genus?

    <p>Gram-negative cocobacilli in pairs</p> Signup and view all the answers

    Which of the following is NOT a method for identifying Klebsiella colonies?

    <p>Blood culture</p> Signup and view all the answers

    Which feature describes the lactose fermentation capability of Klebsiella on MacConkey agar?

    <p>Red colonies indicating lactose positive</p> Signup and view all the answers

    What is the biochemically significant result of Klebsiella on TSI agar?

    <p>H2S negative, glucose positive, lactose and sucrose positive</p> Signup and view all the answers

    What identification technique uses the Quellung reaction?

    <p>Antigenic structure identification</p> Signup and view all the answers

    Which antibiotic resistance phenotype is NOT typically associated with Klebsiella pneumoniae?

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

    Which of the following media is suitable for cultivating Klebsiella species?

    <p>Lactose agar</p> Signup and view all the answers

    What characteristic identifies Pseudomonas aeruginosa as an obligate aerobic organism?

    <p>It requires oxygen for growth.</p> Signup and view all the answers

    Which specimen type is NOT associated with Pseudomonas aeruginosa infections?

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

    What property of Pseudomonas aeruginosa makes it resistant to cetrimide?

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

    Which biochemical pattern is characteristic of Pseudomonas aeruginosa?

    <p>Oxidase positive and glucose non-fermenter</p> Signup and view all the answers

    Which type of colony morphology is observed when Pseudomonas aeruginosa is cultivated in liquid media?

    <p>Pellicle with a pigmented ring beneath</p> Signup and view all the answers

    In microscopy, what type of bacteria morphology is observed for Pseudomonas aeruginosa?

    <p>Gram-negative bacilli with flagella</p> Signup and view all the answers

    What is the significance of pyocyanin production by Pseudomonas aeruginosa?

    <p>It is a virulence factor specific to this bacterium.</p> Signup and view all the answers

    What type of hemolysis is typically associated with Pseudomonas aeruginosa on a blood agar plate?

    <p>Beta hemolysis</p> Signup and view all the answers

    Which agar medium is selective for Aspergillus species?

    <p>Czapek medium</p> Signup and view all the answers

    What is a characteristic feature of Penicillium spp. under microscopy?

    <p>Straight or branched conidiophores</p> Signup and view all the answers

    What is the typical incubation temperature for deep site infections?

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

    Which fungus is known to be pathogenic for humans from the Penicillium genus?

    <p>P.marneffei</p> Signup and view all the answers

    How long do superior molds typically take to grow in culture?

    <p>24 hours to 5 days</p> Signup and view all the answers

    Which characteristic is NOT used in identifying fungi through microscopy?

    <p>Chemical composition of spores</p> Signup and view all the answers

    What type of conidiophores does Aspergillus spp. possess?

    <p>Straight conidiophores</p> Signup and view all the answers

    What is a common feature of Fusarium species?

    <p>Has over 100 known species</p> Signup and view all the answers

    What type of test is FTA-Abs?

    <p>Treponemal serological test</p> Signup and view all the answers

    Which test is characterized by agglutination reactions?

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

    What is a major disadvantage of non-treponemal serological tests?

    <p>They give false-positive reactions.</p> Signup and view all the answers

    What is required for maintaining stock strains of Treponema pallidum?

    <p>Rabbit testicles</p> Signup and view all the answers

    What can treponemal tests not be used to monitor?

    <p>Disease evolution</p> Signup and view all the answers

    What does PCR stand for in the context of Treponema pallidum testing?

    <p>Polymerase Chain Reaction</p> Signup and view all the answers

    Why are treponemal tests not suitable for monitoring disease evolution?

    <p>Antibody levels do not correlate with disease course.</p> Signup and view all the answers

    What type of bacterium is Mycobacterium tuberculosis?

    <p>Strictly aerobic</p> Signup and view all the answers

    What type of staining is used to identify Treponema pallidum in tissue samples?

    <p>Silver stain</p> Signup and view all the answers

    What is the main characteristic of VDRL tests?

    <p>They are rapid and inexpensive.</p> Signup and view all the answers

    Study Notes

    Bacterial Infections

    • Diagnosis of infections caused by cocci (Staphylococcus spp., Streptococcus spp., Enterococcus spp., Neisseria spp., Haemophilus spp.)

    Gram positive bacteria

    • Staphylococcus

      • non-fastidious
      • catalase positive
      • oxidase negative
      • aerobic, facultative anaerobic Gram-positive cocci
      • classification based on free coagulase production
      • coagulase-positive: S. aureus
      • coagulase-negative staphylococci (CNS): S. lugdunensis, S. schleiferi, S. hyicus, S. epidermidis, S. haemolyticus, S. saprophyticus, etc.

    • Streptococcus

      • aerobic, facultative anaerobic Gram-positive cocci
      • some species are obligate anaerobic
      • medically important streptococci prefer a CO2 enriched atmosphere
      • some of the species are fastidious
      • catalase negative
      • oxidase negative

    • Enterococcus

      • non-fastidious
      • catalase negative
      • oxidase negative
      • aerobic, facultative anaerobic Gram-positive cocci

    Gram negative bacteria

    • Neisseria spp.

      • saprophytic, non-fastidious
      • pathogenic; Neisseria meningitidis
      • pathogenic; Neisseria gonorrhoeae

    • Haemophilus spp.

      • Haemophilus influenzae
      • Haemophilus parainfluenzae
      • Haemophilus aegyptius
      • Haemophilus ducreyi
      • other Haemophilus species

    Other Bacteria

    • Vibrio cholerae
      • aerobic, oxidase positive, glucose fermenter Gram-negative curved rod
      • found in aquatic environments.
      • Serogroups 01 and 0139 cause cholera
    • Klebsiella genus
    • Proteus genus
    • Shigella genus
    • Salmonella genus
    • Yersinia enterocolitica
      • Acinetobacter genus

    Treponema pallidum

    • The causative agent of syphilis

    • a sexually transmitted disease

    • specific tests (Confirmatory tests):

    • FTA-Abs (Fluorescent Treponemal Antibody Absorption Test)

    • TPPA (Treponema pallidum hemagglutination assay)

    • ELISA

    • Non-specific tests (Screening tests):

      • VDRL (Venereal Disease Research Laboratory) – flocculation tests (precipitation in liquid medium)
      • RPR (Rapid Plasma Reagin Test) - agglutination

    Mycobacterium tuberculosis

    • strictly aerobic rod-shaped bacterium
    • cannot be stained by Gram due to high lipids in cell wall
    • causative agent of tuberculosis
    • pulmonary tuberculosis (sputum/secretions/gastric secretion in infants)
    • renal tuberculosis (urine)
    • genital tuberculosis (vaginal/sperm/prostatic secretions)
    • joint, bone tuberculosis (joint fluid/pus)
    • lymph node tuberculosis (lymph node aspirate/pus)
    • meningitis (CSF)
    • Microscopy: Ziehl-Neelsen stain (acid-fast staining) and Kinyoun stain.
    • Acid-fast stain: positive for Mycobacterium spp., Nocardia spp., Legionella micdadei, Rhodococcus spp
    • PCR and mass spectrometry used for testing
    • Cultivation: Lowenstein-Jensen agar, a specific selective medium

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    Diagnosis of Infections Caused by Cocci PDF

    Description

    This quiz tests your knowledge on the Lancefield classification of streptococci and the characteristics of Proteus species. Questions cover specimen collection, biochemical patterns, and growth characteristics relevant to clinical microbiology. Challenge yourself and deepen your understanding of these important bacteria in infectious diseases.

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