Upper Respiratory Tract Infections Quiz
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Questions and Answers

Which microbial disease is specifically linked to Streptococcus pyogenes?

  • Common cold
  • Streptococcal pharyngitis (correct)
  • Tonsillitis
  • Influenza

    • What characteristic of Streptococcus pyogenes is significant for its virulence?

  • It forms spores for survival.
  • It produces exotoxins.
  • It has a thick peptidoglycan layer.
  • It is a facultative anaerobe. (correct)

    • What symptom is NOT commonly associated with an upper respiratory tract infection?

  • Skin rash (correct)
  • Rhinorrhea
  • Pharyngitis
  • Fever

    • Which factor contributes significantly to the development of rheumatic fever in infections caused by Streptococcus pyogenes?

    <p>M-protein</p> Signup and view all the answers

    What type of hemolysis is associated with Streptococcus pyogenes?

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

    Which of the following is NOT a property of Streptococcus pyogenes?

    <p>Produces alpha hemolysin</p> Signup and view all the answers

    How does Streptococcus pyogenes evade host defenses?

    <p>With hyaluronic acid capsules</p> Signup and view all the answers

    Which of the following statements is true regarding respiratory pathogens?

    <p>Viruses can cause similar symptoms.</p> Signup and view all the answers

    What is the optimal temperature for the growth of Streptococcus pyogenes?

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

    In the context of upper respiratory infections, what does the term 'professional invaders' refer to?

    <p>Organisms that can overcome host defenses in a healthy state</p> Signup and view all the answers

    What is the primary site of latency for adenoviruses?

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

    Which of the following diseases is not associated with adenoviruses?

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

    Which treatment is effective for rhinovirus infections?

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

    Which of these organisms is the most common cause of pneumonia mentioned?

    <p>S. pneumoniae</p> Signup and view all the answers

    What role do corticosteroids play in the treatment of certain infections?

    <p>Reduce edema</p> Signup and view all the answers

    Which of the following is true about the transmission of adenoviruses?

    <p>Involves direct contact including eye exposure</p> Signup and view all the answers

    What is the primary etiology of diphtheria?

    <p>Corynebacterium diphtheriae</p> Signup and view all the answers

    Which of the following tests is NOT associated with the diagnosis of acute pharyngitis caused by Streptococcus pyogenes?

    <p>Modified Elek test</p> Signup and view all the answers

    In which condition is the presence of a pseudomembrane in the throat most characteristic?

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

    What is the primary action of the diphtheria toxin?

    <p>Causing cytotoxic effects on tissue</p> Signup and view all the answers

    Which specimen type is considered optimal for the laboratory diagnosis of diphtheria?

    <p>Dacron swabs from nose or throat</p> Signup and view all the answers

    Which antibiotic is not typically used for the management of diphtheria?

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

    What is the main complication associated with epiglottitis?

    <p>Respiratory arrest</p> Signup and view all the answers

    Which of the following is a method for the laboratory diagnosis of diphtheria?

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

    Which of the following viruses is associated with acute pharyngitis?

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

    What type of colonies would you expect to find on a Tellurite agar plate inoculated with Corynebacterium diphtheriae?

    <p>Brown to black colonies with brown-black halo</p> Signup and view all the answers

    Which of the following structures is not part of the upper respiratory tract?

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

    What distinguishes professional invaders from secondary invaders in the respiratory tract?

    <p>Professional invaders can cause infection in healthy individuals.</p> Signup and view all the answers

    Which of the following pairs correctly matches an anatomical division to its components?

    <p>Lower respiratory tract - trachea</p> Signup and view all the answers

    What is the primary role of the normal flora of the respiratory tract?

    <p>To prevent the entry of professional invaders.</p> Signup and view all the answers

    Which statement about the respiratory tract is accurate?

    <p>Infection can spread from the respiratory tract to other parts of the body.</p> Signup and view all the answers

    Which of the following is a characteristic of secondary invaders in the respiratory tract?

    <p>They require a pre-existing condition to infect.</p> Signup and view all the answers

    What is the primary function of the epiglottis in the upper respiratory system?

    <p>To prevent food from entering the trachea.</p> Signup and view all the answers

    Which of the following structures is primarily responsible for the exchange of gases?

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

    Which characteristic is true about the nasal cavity in the upper respiratory tract?

    <p>It plays a role in filtering and humidifying inhaled air.</p> Signup and view all the answers

    What is the role of Streptolysin O among the virulence factors of S. pyogenes?

    <p>Lyses leukocytes and releases immunogenic lysosomal enzymes</p> Signup and view all the answers

    Which virulence factor of S. pyogenes degrades complement C5a?

    <p>C5a peptidase</p> Signup and view all the answers

    How does DNAse function as a virulence factor for S. pyogenes?

    <p>It destroys neutrophil extracellular traps</p> Signup and view all the answers

    What symptom is commonly associated with Streptococcal Pharyngitis?

    <p>High fever and hyperemic tonsils with exudates</p> Signup and view all the answers

    Which factor contributes to the antiphagocytic properties of S. pyogenes?

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

    What is the treatment of choice for Streptococcal Pharyngitis?

    <p>Penicillin G</p> Signup and view all the answers

    Which factor plays a key role in the adherence of S. pyogenes to epithelial cells?

    <p>M protein</p> Signup and view all the answers

    What non-suppurative complication can result from S. pyogenes infection?

    <p>Acute rheumatic fever</p> Signup and view all the answers

    What type of bacteria is Streptococcus pyogenes classified as?

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

    How does Streptokinase contribute to the virulence of S. pyogenes?

    <p>It helps to lyse blood clots for tissue spread</p> Signup and view all the answers

    Study Notes

    Upper Respiratory Tract Infections

    • Pathogens that Gain Entry Through the Upper Respiratory Tract:
      • Professional invaders infect healthy respiratory tracts.
      • Examples: Respiratory viruses (due to attachment mechanisms that evade host defenses).
      • Secondary invaders cause disease when host defenses are impaired.
      • Symptoms: Fever, rhinitis, pharyngitis, sore throat.

    Bacterial Agents

    • Streptococcal Pharyngitis (Streptococcus pyogenes)
      • Gram-positive cocci in pairs or long chains.
      • Group A strain with hyaluronic acid capsules (antiphagocytic).
      • Facultative anaerobe.
      • Beta-hemolytic (grow best at 10% CO2 and 37C).
      • PYR-positive (hydrolyzes L-pyrrolidony 1-β-naphthylamide).
      • Bacitracin susceptible.

    Virulence Factors of S. pyogenes

    • Streptolysin S: Lyses leukocytes, platelets, and erythrocytes. Stimulates release of lysosomal enzymes. Non-immunogenic.
    • Streptolysin O: Lyses leukocytes, platelets, and erythrocytes. Stimulates release of lysosomal enzymes. Immunogenic.
    • Streptokinase: Lyses blood clots, facilitates spread of bacteria in tissues. Used to treat acute MI.
    • DNAse: Destroys neutrophil extracellular traps (NETs), which kill extracellular microbes.
    • C5a peptidase: Degrades complement C5a.
    • Capsule: Antiphagocytic.
    • Lipoteichoic acid: Binds to epithelial cells.
    • F protein: Mediates adherence to epithelial cells and internalization.
    • M protein: Adhesion and antiphagocytosis activity.

    Streptococcal Pharyngitis Transmission and Presentation

    • Transmission: Direct person-to-person.
    • Presentation: High fever, malaise, headache, hyperemic tonsils with yellowish exudates, enlarged and tender submandibular lymph nodes, peritonsillar abscess, retropharyngeal abscess. Can be asymptomatic.

    Streptococcal Pharyngitis Non-Suppurative Complications

    • Acute Rheumatic Fever: Antibody to M-protein cross-reacts with heart valves. Most serious sequela of S. pyogenes.
    • Acute Glomerulonephritis: Immune complex formation.

    Diphtheria (Corynebacterium diphtheriae)

    • Etiology: Gram-positive rod with irregular swelling at one end (club-shaped).
    • Morphology: Palisade arrangement with metachromatic granules (staining deeply with aniline dyes). Beaded appearance.
    • Culture: Agar with potassium tellurite produces brown to black colonies with a brown-black halo.

    Diphtheria Pathogenesis

    • Diphtheria toxin: Heat-labile, single-chain, three-domain polypeptide. Lethal dose: 0.1 ug/kg body weight.

    Diphtheria Presentation

    • Sore throat, low-grade fever, prostration.
    • Pseudomembrane (tough grayish membrane in the throat containing fibrin, dead tissue, and bacterial cells).
    • Dyspnea from obstruction.

    Otitis Media

    • Etiology: Middle ear infection.
    • Presentation: More common in children, complication of common cold or any infection of the nose/throat.

    Epiglottitis

    • Etiology: Inflammation of the epiglottis or nearby structures including arytenoids, aryepiglottic folds, and vallecula.
    • Presentation: Life-threatening infection that causes profound swelling of the upper airways, leading to asphyxia and respiratory arrest.

    Etiology of Bacterial Pneumonia

    • H. influenzae type b (Hib) is the most common cause
    • Other bacteria causing pneumonia include:
      • Non-encapsulated H. influenzae
      • Moraxella catarrhalis
      • Streptococcus pneumoniae
      • Streptococcus pyogenes
      • Staphylococcus aureus
      • Pseudomonas aeruginosa
      • Candida
    • DPT vaccination provides active immunization against Hib

    Treatment

    • Secure airway:
      • Endotracheal intubation
      • Tracheostomy
    • Corticosteroids reduce edema
    • Antibiotics are required to treat bacterial infections

    Adenoviruses

    • Family: Adenoviridae
    • 51 serotypes
    • Only virus with fiber: Penton
    • Predisposition: Mucosal epithelial cells of the respiratory, gastrointestinal, and conjunctiva
    • Transmission: Respiratory, fecal-oral, direct contact (eye)
    • Disease:
      • Pharyngitis
      • Keratoconjunctivitis
      • Coryza
      • Bronchiolitis
      • Atypical pneumonia
      • Hemorrhagic cystitis
      • Acute Gastroenteritis
      • Disseminated disease
    • Site of Latency: Replication occurs in the oropharynx

    Rhinovirus

    • Family: Picornaviridae
    • Most common cause of common colds
    • More than 100 serotypes: Makes immunity difficult
    • Transmission: Respiratory droplets
    • Treatment:
      • Supportive therapy: Antihistamines, cough suppressants, hydration
    • No vaccine available
    • Killed by gastric acid, so cannot cause gastrointestinal disease when swallowed

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    Upper Respiratory Tract PDF

    Description

    Test your knowledge on upper respiratory tract infections, focusing on pathogens that invade through this system. Learn about bacterial agents like Streptococcus pyogenes and their virulence factors. This quiz highlights infection mechanisms and symptoms associated with respiratory illnesses.

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