Gram-Negative Cocci Overview
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Questions and Answers

Which characteristic is NOT associated with Neisseria gonorrhoeae?

  • Pili presence
  • Oxidase-positive
  • Gram-negative diplococci
  • Presence in normal flora (correct)

    • Which disease is primarily caused by Neisseria gonorrhoeae?

  • Meningococcemia
  • Meningitis
  • Pelvic inflammatory disease
  • Gonorrhea (correct)

    • What media is suitable for growing Neisseria gonorrhoeae?

  • Blood agar
  • MacConkey agar
  • Chocolate agar (correct)
  • Nutrient agar

    • Which transport system is used for Neisseria gonorrhoeae?

    <p>JEMBEC system</p> Signup and view all the answers

    What is a significant symptom of the diseases caused by Neisseria gonorrhoeae?

    <p>Urogenital infections</p> Signup and view all the answers

    Which feature distinguishes Neisseria species from other Gram-negative cocci?

    <p>Fastidious growth requirements</p> Signup and view all the answers

    What is the main characteristic of Neisseria species regarding temperature preferences?

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

    What is a characteristic feature of meningitidis?

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

    What is a consequence of Waterhouse-Friderichsen syndrome?

    <p>Adrenal gland failure</p> Signup and view all the answers

    Which community setting is associated with outbreaks of meningitis caused by meningococci?

    <p>Close communities</p> Signup and view all the answers

    What type of growth media supports the growth of meningitidis?

    <p>Chocolate (CHOC) agar</p> Signup and view all the answers

    What is the significance of complement deficiencies in meningococcal infections?

    <p>They predispose individuals to infections.</p> Signup and view all the answers

    Which characteristic distinguishes Moraxella catarrhalis from other respiratory pathogens?

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

    What complication is often associated with M. catarrhalis infections?

    <p>Otitis media</p> Signup and view all the answers

    What is the primary resistance mechanism of M. catarrhalis to antibiotics?

    <p>Beta-lactamase production</p> Signup and view all the answers

    Which class of antibiotics is M. catarrhalis particularly resistant to?

    <p>Beta-lactams</p> Signup and view all the answers

    Which growth condition is NOT required for Haemophilus species?

    <p>High temperature incubation</p> Signup and view all the answers

    What is a characteristic that differentiates H. ducreyi from other Haemophilus species?

    <p>Causes genital ulcers</p> Signup and view all the answers

    Which Haemophilus species requires growth factors X and V?

    <p>H. ducreyi</p> Signup and view all the answers

    Which of the following is NOT a Gram-negative coccobacilli?

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

    Which statement is true about H. parainfluenzae?

    <p>It shows a positive porphyrin test.</p> Signup and view all the answers

    Which statement accurately describes Acinetobacter baumannii?

    <p>It exhibits high levels of intrinsic and acquired antimicrobial resistance.</p> Signup and view all the answers

    What is a common condition associated with H. aegyptius?

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

    What characteristics are associated with Escherichia coli?

    <p>It produces acid and gas, and is often found in the GI tract.</p> Signup and view all the answers

    What is a common misidentification for H. ducreyi due to its morphology?

    <p>Neisseria gonorrhoeae</p> Signup and view all the answers

    Which of the following is true regarding Salmonella spp.?

    <p>They are characterized by being motile and producing hydrogen sulfide.</p> Signup and view all the answers

    Which species is NOT part of the normal flora but can be pathogenic?

    <p>H. influenzae</p> Signup and view all the answers

    Which factor do all Haemophilus species share regarding their growth characteristics?

    <p>Fastidious growth requirements</p> Signup and view all the answers

    What differentiates Pseudomonas aeruginosa from other Enterobacteriaceae members?

    <p>It possesses a metallic green sheen on EMB agar.</p> Signup and view all the answers

    What is the appearance of H. ducreyi colonies typically described as?

    <p>School of fish arrangement</p> Signup and view all the answers

    Which aspect of pathogenic Gram-negative rods is generally common among them?

    <p>They share the ability to colonize the GI tract as normal flora.</p> Signup and view all the answers

    What is a characteristic feature of Kingella kingae?

    <p>It is a Gram-negative coccobacillus that is oxidase-positive.</p> Signup and view all the answers

    Which of the following infections is commonly associated with Pasteurella multocida?

    <p>Soft tissue infections following animal bites.</p> Signup and view all the answers

    Which of the following statements about Kingella kingae is true?

    <p>It is a common cause of osteoarticular infections in children.</p> Signup and view all the answers

    What type of staining is used to identify Pasteurella multocida?

    <p>Gram staining.</p> Signup and view all the answers

    Which feature is NOT associated with Kingella kingae?

    <p>Catalase positive.</p> Signup and view all the answers

    What clinical condition can Pasteurella multocida cause?

    <p>Cellulitis.</p> Signup and view all the answers

    What morphological characteristic can be observed when staining Kingella kingae?

    <p>Bipolar staining resembling safety pins.</p> Signup and view all the answers

    Which biochemical test can differentiate Pasteurella multocida from other bacterial species?

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

    In pediatric patients, which species is a common cause of septic arthritis?

    <p>Kingella kingae.</p> Signup and view all the answers

    What type of hemolysis is exhibited by Pasteurella multocida on culture media?

    <p>Gamma hemolytic.</p> Signup and view all the answers

    Study Notes

    Gram-Negative Cocci

    • Genus: Neisseria

      • Species: N. gonorrhoeae
        • Characteristics: Gram-negative diplococci, oxidase-positive, catalase-positive, glucose-positive, fastidious, encapsulated, pili
        • Growth: No growth on MAC, grows on CHOC
        • Diseases: Gonorrhea (STI), can cause PID, Fitz-Hugh-Curtis syndrome
        • Key Points: Not normal flora, primarily infects the urogenital tract, carried in nasopharynx
      • Species: N. meningitidis
        • Characteristics: Gram-negative diplococci, oxidase-positive, maltose-positive, glucose-positive, fastidious, encapsulated
        • Growth: Growth on CHOC, BAP, SBA
        • Diseases: Meningitis, meningococcemia, Waterhouse-Friderichsen syndrome
        • Key Points: Carried in nasopharynx, can cause outbreaks in close communities, causes eye infection in children

    • Genus: Moraxella

      • Species: M. catarrhalis
        • Characteristics: Gram-negative diplococci, oxidase-positive, catalase positive, beta-lactamase, asaccharolytic
        • Growth: Growth on CHOC, BAP, not on MAC
        • Diseases: Otitis media, sinusitis, bronchitis
        • Key Points: Common cause of respiratory infections, especially in children

    Gram-Negative Coccobacilli

    • Genus: Haemophilus

      • Species: H. influenzae
        • Characteristics: Small Gram-negative coccobacilli, fastidious, grows on CHOC, requires X & V factors
        • Diseases: Meningitis, pneumonia, otitis media, epiglottitis, (invasive and non-invasive)
        • Key Points: Most invasive diseases are type B, Hib vaccine has reduced infections. Uses virulence factors like capsule, IgA protease, etc
      • Species: H. ducreyi
        • Characteristics: Gram-negative coccobacilli, fastidious, growth around X and XV
        • Diseases: Chancroid
      • Species: H. parainfluenzae
        • Characteristics: Gram-negative coccobacilli, fastidious, growth around V and XV factor
        • Diseases: Rarely pathogenic, endocarditis

    • Genus: HACEK Group

      • Species: Haemophilus aphrophilus, Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis
      • Characteristics- Gram-negative coccobacillus, requires X factor for growth, CO2 increased, grows on chocolate and BAP.
      • Diseases: Endocarditis, respiratory infections, meningitis
      • Key Points- part of normal flora in upper respiratory system

    • Genus: Pasteurella

      • Species: P. multocida
        • Characteristics: Gram-negative bacilli, non-fastidious - grow on BAP and CHOC. Gamma hemolytic, Nonmotile, Oxidase-posititve (in Most isolates), nitrate positive.
        • Diseases: Animal bite infections, cellulites.
        • Key Points: Can be easily mistaken for Haemophilus, often ovoid, filamentous, or bacilli-shaped, with bipolar staining, retaining more stain in the ends

    • Genus: Kingella

      • Species: K. kingae
        • Characteristics: Gram-negative coccobacillus, non-motile, sugar fermentor that produces no gas, Oxidase positive, catalase negative
        • Diseases: Osteoarticular infections, bacteremia
      • Key Points: May be mistaken for Neisseria (gram stain identification).

    • Genus: Enterobacter

      • Species: Enterobacter spp.
        • Characteristics: Gram-negative rods, pink/colorless colonies on MAC, facultative anaerobe, motile, large shiny colonies on BAP, H2S negative, oxidase negative, indole variable
        • Diseases: UTI, pneumonia, wound infection
        • Key Points: Known for multidrug resistance.

    • Genus: Salmonella

    • Species: S. enterica

      • Characteristics: Gram-negative rods, non-lactose fermenting, facultative anaerobe, motile
      • Diseases: Gastroenteritis, enteric fever (Typhoid),
      • Key Points: Produces H2S (except S. paratyphi A)

    • Genus: Shigella

      • Species: Shigella spp.
        • Characteristics: Gram-negative rods, non-lactose fermenting, facultative anaerobe, non-motile, RED colonies on XLD, GREEN/clear on HE
        • Diseases: Dysentery, blood diarrhea, inflammatory disease
        • Key Points: Non-motile, can invade epithelial cells, no H antigen, no gas production, (except in some S.flexneri).

    • Genus: Yersinia

      • Species: Y. enterocolitica
        • Characteristics: Gram-negative rods, non-lactose fermenting, facultative anaerobe, safety pin, colonies vary based on temperature
        • Diseases: Gastroenteritis, appendicitis-like syndrome. plague (Y. pestis)
          • Key Points: Motile at 25°C, but not at 37°C. Resists phagocytosis, invades intestinal mucosa

    • Genus: Pseudomonas

      • Species: P. aeruginosa
      • Characteristics: Slender gram-negative rods, motile, polar flagella, oxdiase positive, BAP with metallic sheen
      • Diseases: Nosocomial UTI, pneumonia, wound infection
      • Key Points: Fruity/grape-like odor.

    • Genus: Acinetobacter

      • Species: A. baumannii
        • Characteristics: Gram-negative coccobacilli, grows on MAC, nonmotile, oxidase-negative, no pigment.
        • Diseases: Nosocomial UTI, pneumonia
      • Key Points: Small coccobacilli, can falsely stain as gram-positive.

    • Genus: Stenotrophomonas

      • Species: S. maltophilia
        • Characteristics: Gram-negative rods, grow on MAC, nonmotile, oxidase-negative.
        • Diseases: Nosocomial UTI, pneumonia
      • Key Points: Strong ammonia smell, DNase positive.

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    Bacterial Characteristics & Diseases PDF

    Description

    Explore the characteristics, diseases, and clinical significance of Gram-negative cocci, specifically focusing on the genera Neisseria and Moraxella. This quiz covers key features of N. gonorrhoeae, N. meningitidis, and M. catarrhalis, including their growth conditions and associated diseases.

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