Microbiology Quiz: Neisseria and Clostridium
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Questions and Answers

What shape does Neisseria meningitidis resemble?

  • Spiral
  • Rod
  • Kidney bean (correct)
  • Circle

    • Which condition is primarily caused by Neisseria meningitidis?

  • Pneumonia
  • Epidemic cerebrospinal meningitis (correct)
  • Strep throat
  • Tuberculosis

    • What facilitates the growth of Neisseria meningitidis in culture media?

  • High oxygen levels
  • Presence of carbon dioxide 5-10% (correct)
  • Low humidity
  • Temperature above 50°C

    • Which of the following is a common symptom of meningococcal meningitis?

    <p>Stiff neck (A)</p> Signup and view all the answers

    What role does the meningococcal capsule serve in its pathogenicity?

    <p>Acts as an anti-phagocyte structure (C)</p> Signup and view all the answers

    Which of the following is NOT true about Neisseria meningitidis?

    <p>They are aerobic organisms. (B)</p> Signup and view all the answers

    What can result from untreated bacterial meningitis?

    <p>Brain damage or hearing loss (C)</p> Signup and view all the answers

    Which antibiotics are commonly used to treat meningococcal infections?

    <p>Ceftriaxone and chloramphenicol (D)</p> Signup and view all the answers

    Which Clostridium species is primarily associated with gas gangrene?

    <p>Clostridium perfringens (B)</p> Signup and view all the answers

    What morphological characteristic do Clostridium species exhibit under a microscope?

    <p>Spindle-shaped cells with a bulge (D)</p> Signup and view all the answers

    Which of the following toxins is produced by Clostridium difficile?

    <p>Enterotoxin A (C)</p> Signup and view all the answers

    How is Clostridium difficile primarily diagnosed in laboratory settings?

    <p>Demonstration of toxins in a stool sample (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of enteric bacteria within the Enterobacteriaceae family?

    <p>Always pathogenic (B)</p> Signup and view all the answers

    Which of the following Clostridium species was reclassified into a new genus in 2016?

    <p>Clostridium difficile (A)</p> Signup and view all the answers

    Which statement accurately describes the lesions of cutaneous diphtheria?

    <p>They consist of skin ulcerations with no healing tendency. (D)</p> Signup and view all the answers

    What is a common consequence of antibiotic therapy concerning Clostridium difficile?

    <p>Reduction in normal flora leading to CDI (B)</p> Signup and view all the answers

    Under Gram staining, how do Clostridium bacteria appear?

    <p>Gram-positive rods (C)</p> Signup and view all the answers

    What is the required emergency treatment for laryngeal diphtheria?

    <p>Tracheotomy for airway clearance (D)</p> Signup and view all the answers

    What is a defining morphological characteristic of Listeria species?

    <p>Gram-positive bacilli and facultative anaerobic rods (B)</p> Signup and view all the answers

    At which temperatures can Listeria species grow?

    <p>0–45°C (B)</p> Signup and view all the answers

    Which of the following metabolic characters is characteristic of the genus Listeria?

    <p>Catalase activity present (A)</p> Signup and view all the answers

    What significant condition is primarily caused by Listeria monocytogenes in humans?

    <p>Sepsis and meningitis in newborns (D)</p> Signup and view all the answers

    What symptom is commonly associated with listeriosis in humans?

    <p>Nausea, vomiting, and diarrhea (C)</p> Signup and view all the answers

    Which group of people is at particular risk for listeriosis?

    <p>Elderly and immune-suppressed individuals (A)</p> Signup and view all the answers

    Which of the following is a morphological character of Moraxella catarrhalis?

    <p>Non-spore forming and non motile (C)</p> Signup and view all the answers

    What color colonies does Corynebacterium diphtheriae form on Tinsdale medium?

    <p>Black with a brown halo (D)</p> Signup and view all the answers

    Which metabolic character distinguishes Moraxella catarrhalis from other bacteria?

    <p>Catalase and oxidase reactions are positive (D)</p> Signup and view all the answers

    What common condition is associated with Moraxella catarrhalis?

    <p>Bronchitis (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Corynebacterium diphtheriae?

    <p>They produce urease (C)</p> Signup and view all the answers

    What is a key identifying feature of Moraxella catarrhalis on blood agar?

    <p>Small, gray-white, non-hemolytic colonies (C)</p> Signup and view all the answers

    Which media is considered an enrichment medium for Corynebacterium diphtheriae?

    <p>OCST medium (B)</p> Signup and view all the answers

    What complication is associated with Moraxella catarrhalis in elderly patients?

    <p>Bronchopneumonia and exacerbation of COPD (A)</p> Signup and view all the answers

    What is a characteristic feature of Klebsiella colonies on simple agar medium after 48 hours at 37ºC?

    <p>Large and moist, tending to confluence (B)</p> Signup and view all the answers

    How do Salmonella colonies appear on selective medium containing bromothymol blue?

    <p>Small, lactose-negative with a blue tint (C)</p> Signup and view all the answers

    Which of the following statements about Escherichia coli is incorrect?

    <p>Its colonies are typically green on Drigalski medium. (C)</p> Signup and view all the answers

    What distinguishes Proteus colonies on blood agar?

    <p>They exhibit swarming mobility. (A)</p> Signup and view all the answers

    Which characteristic is typical for Shigella colonies on selective medium?

    <p>Transparent and bright in color (D)</p> Signup and view all the answers

    Which phenomenon is associated with the appearance of Proteus colonies on agar?

    <p>Swarming (A)</p> Signup and view all the answers

    In what manner do Pseudomonas colonies appear on blood agar?

    <p>Gray and shiny with β-hemolysis (A)</p> Signup and view all the answers

    What fills the stools in patients experiencing dysentery caused by Shigella?

    <p>Mucus and blood (C)</p> Signup and view all the answers

    Which bacterium is primarily associated with urinary infections?

    <p>Proteus mirabilis (B)</p> Signup and view all the answers

    What factor is essential for oxidation-reduction processes in Haemophilus spp.?

    <p>V factor (B)</p> Signup and view all the answers

    Which species of Haemophilus is known to frequently cause meningitis in children?

    <p>Haemophilus influenzae (A)</p> Signup and view all the answers

    Which of the following bacteria is NOT typically associated with genital infections?

    <p>Salmonella (D)</p> Signup and view all the answers

    Which of the following infections is primarily caused by Escherichia coli?

    <p>Urinary infections (D)</p> Signup and view all the answers

    What type of infections is Klebsiella commonly associated with?

    <p>Purulent infections and respiratory infections (A)</p> Signup and view all the answers

    What distinguishes Haemophilus spp. in terms of growth requirements?

    <p>They require X and V factors for growth. (C)</p> Signup and view all the answers

    Which species causes chancroid, a venereal infection?

    <p>Haemophilus ducreyi (D)</p> Signup and view all the answers

    Study Notes

    Neisseria Meningitidis

    • Gram-negative cocci, kidney-shaped (coffee bean shape), arranged in diplococci
    • Found intracellularly in cerebrospinal fluid
    • Newly isolated strains have a polysaccharide capsule
    • Non-motile and non-spore forming

    Neisseria Gonorrhoeae

    • Gram-negative cocci, kidney-shaped (coffee bean shape), arranged in diplococci
    • Predominantly intracellular (phagocytosed by polymorphonuclears)
    • Non-spore forming, immobile
    • May have a capsule in pathological products and in young cultures

    Moraxella Catarrhalis

    • Gram-negative diplococcus that resists decolorization
    • Non-spore forming, non-capsulated, and non-motile
    • Larger than meningococcus or gonococcus

    Corynebacterium Diphtheriae

    • Gram-positive bacilli with swollen ends, "Chinese lettering" arrangement
    • Non-spore forming, non-ciliated, and encapsulated
    • Contains metachromatic granules (Babes-Ernst) visible with Del Vecchio stain
    • Several growth media can be used
      • Enrichment media: OCST (egg, cysteine, serum, potassium tellurite)
      • Elective Löffler's medium (with ox coagulated serum)
      • Solid selective media (blood and potassium tellurite)
      • Tinsdale and Gundel-Tietz
      • Blood-agar medium
    • Colonies vary depending on the media used
      • On Löffler's medium, white and convex
      • On Tinsdale medium, black with a brown halo
      • On solid media containing potassium tellurite and blood, three types exist: gravis – large, black colonies, rough surface, irregular margins (pathogenic) mitis – smaller, black colonies with smooth surface, circular margins intermedius – grey-black colonies with irregular margins
    • Ferments glucose and maltose (without gas production)
    • Some strains (gravis) can ferment sucrose
    • Urease is negative
    • Diphtheria toxin (highly immunogenic) is a key antigen
    • Possesses corpuscular antigens (carbohydrate and protein nature)
    • Toxin remains at entrance gate, diffusing throughout body to cause damage
    • Toxin can produce necrotic lesions
    • Produces, toxigenic strains are lysogenic

    Listeria

    • Gram-positive bacilli, non-spore forming, facultative anaerobic
    • Size varies (0.4-0.5 µm in diameter, 1-2 µm long) with rounded ends
    • Non-encapsulated
    • Motile via peritrichous flagella at temperatures ≤30°C
    • Several growth media can be used:
      • Various temperatures (0-45°C)
      • pH 6-9, and various salt concentrations (including 10%NaCl)
    • On blood agar: beta-hemolytic, small, grey, translucent drop-like colonies.
    • On tryptose agar: green-blue colonies
    • Catalase positive, and oxidase negative.
    • Positive methyl red reaction, positive Voges-Proskauer reaction
    • Does not produce indole, utilize citrate or possess urease activity
    • Causes meningitis and sepsis, particularly in newborns and adults
    • Also diarrheagenic, through ingestion of unpasteurized milk products, leading to bacteremia and septicemia, and meningoencephalitis
    • Risk factors include newborns, pregnant women, elderly people with poor immune systems, and people whose immune systems are weak
    • Can cause placentitis, neonatal septicemia, and abortion (if transmitted)

    Bacillus Anthracis

    • Gram-positive, non-motile, rectangular, aerobic, rod-shaped bacterium (with square ends) and capsulated

    • Chain formation is common

    • Spores are formed easily when discharged from infected animal or isolated bacteria from animal carcass exposed to free oxygen, therefore the carcass should not be necropsied in case of anthrax

    • Growth occurs as flocular deposits in broth media

    • On blood agar: non-hemolytic colonies with rough, uneven surfaces and multiple curled extensions at the edge (Medusahead)

    • Catalase positive, hemolysis negative

    • Indole positive, motility negative

    • Oxidase negative, urease negative.

    • Ferments glucose, maltose, sucrose, and trehalose

    • Anthrax toxin is complex with 3 protein components: I (edema factor), II (protective factor), and III (lethal factor).

    • Components I and II cause mild edema (low overall mortality), while component III causes high lethality

    • Four forms of naturally occurring human anthrax infections exist: -Cutaneous - spores enter through skin breaks and lead to a painless ulcer with black scab formation. -Gastrointestinal - infection upon eating contaminated meat, mouth, and throat are main entry points though it's not expected to result from aerosolized spores -Inhalation - breathing spores into the lungs -Injection- related, injection heroin contaminated with spores

    Clostridium

    • Species of Clostridium include :
    • tetani: Tetanus
    • perfringens: Gas gangrene
    • botulinum: Botulism
    • difficile: Pseudomembranous colitis
    • Obligate anaerobes capable of sporulation
    • Gram-positive bacilli
    • Under microscope, they appear as long, irregular, rod-shaped cells with a bulge at the terminal or subterminal end (forming subterminal spores)
    • Various cultural characteristics in regards to oxygen and different growth media
      • c. botulinum: large semitransparent colonies with wavy outlines, beta-hemolytic on most media plates
      • c. tetani: fine film of growth on blood agar media plates, swarming due to motility, hemolytic on blood agar media
      • c. difficile: non hemolytic with large and flat colonies on blood agar media
    • C. difficile is catalase- and superoxide dismutase-negative, producing enterotoxin A and cytotoxin B. It causes a spectrum of symptoms, ranging from mild diarrhea to severe colitis, pseudomembranous colitis, or toxic megacolon, especially as a consequence of antibiotic use

    Enterobacteriaceae

    • Gram-negative bacilli, non-spore forming, typically motile, and do not have a capsule except for Klebsiella

    • Some species are always pathogenic but other species act as saprophytes (e.g. part of normal intestinal flora which contribute to food digestion) and only become pathogenic when they leave their normal habitat

    • Examples of various pathogenic species in the Enterobacteriaceae family include Escherichia coli, Klebsiella, Proteus, and Pseudomonas

    • Species vary in their colonial characteristics -Escherichia coli: colonies are yellow on Istrate-Meitert or Drigalski medium (lactose positive), round, convex, with a medium size -Shigella: transparent, bright colonies, found in the color of the medium (green), also lactose negative; -Salmonella: small, lactose-negative, semi-transparent; some strains have a black center due to hydrogen sulfide -Proteus: produces swarming growth (concentric zones) in simple and blood agar -Klebsiella: large, round, convex colonies with a moist and mucous appearance with large (yellow, round, and convex, moist colonies) on lactose medium -Pseudomonas: small blue colonies, adherent to the medium on Istrate-Meitert medium, gray, shiny colonies surrounded by beta hemolysis on blood agar

    • Numerous clinical features are associated with Enterobacteriaceae infections, including digestive, urinary, respiratory, and ENT, genital, and purulent infections.

    Haemophilus

    • Small, pleomorphic, nonmotile, nonsporing Gram-negative rods, or coccobacilli
    • Aerobic or facultative anaerobic, optimal growth with the addition of 5-10% carbon dioxide in the incubation atmosphere.
    • Oxidase, catalase reactions vary among species
    • require one or both of two accessory growth factors (X and V)

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    Description

    Test your knowledge on Neisseria meningitidis and Clostridium species. This quiz covers various aspects, including shape, pathogenicity, symptoms of infections, and common treatment options. Perfect for microbiology students and professionals looking to refresh their knowledge.

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