Respiratory Tract Infections Overview
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Questions and Answers

Which medium is NOT recommended for culturing the suspected organism in a case of diphtheria?

  • Egg yolk agar
  • Loeffler’s serum
  • Nutrient agar (correct)
  • Blood tellurite medium
  • What is the initial diagnostic method suggested for determining the presence of certain bacilli in a throat swab?

  • Quantitative PCR
  • Blood culture
  • Direct smear (correct)
  • Serological test
  • What is the primary purpose of administering diphtheria antitoxin in treatment?

  • To treat secondary infections
  • To promote bacterial growth
  • To enhance immune response
  • To neutralize the unbound toxin in the blood (correct)
  • Which of the following antibiotics is NOT indicated for the treatment of diphtheria?

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

    What precaution should be taken when administering diphtheria antitoxin?

    <p>Manage for potential anaphylaxis</p> Signup and view all the answers

    What is the purpose of DPT vaccine administration in early childhood?

    <p>To prevent tetanus, diphtheria, and pertussis</p> Signup and view all the answers

    How is diphtheria toxoid prepared?

    <p>By treating the exotoxin with formaldehyde</p> Signup and view all the answers

    What is a key characteristic of the Coxsackie virus?

    <p>It is a non-enveloped virus.</p> Signup and view all the answers

    At what ages is the DPT vaccine administered to children?

    <p>2, 4, 6 months</p> Signup and view all the answers

    What disease is associated with Group A Coxsackie virus?

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

    Which of the following is a virulence factor of Corynebacterium diphtheriae?

    <p>Exotoxin production</p> Signup and view all the answers

    What complication can arise from Corynebacterium diphtheriae infection?

    <p>Airway obstruction</p> Signup and view all the answers

    Which pathogen is the most common cause of epiglottitis?

    <p>Haemophilus influenzae type B</p> Signup and view all the answers

    Which symptom is NOT associated with herpangina caused by Coxsackie virus?

    <p>Vesicular rash on the hands</p> Signup and view all the answers

    What is the primary cause of pharyngitis?

    <p>Viral infection</p> Signup and view all the answers

    In which tissue does adenovirus typically establish latent infection?

    <p>Adenoidal and tonsillar tissues</p> Signup and view all the answers

    Which virus is primarily responsible for bronchiolitis?

    <p>Respiratory syncytial virus</p> Signup and view all the answers

    What type of organism is Corynebacterium diphtheriae classified as?

    <p>Gram-positive club-shaped bacilli</p> Signup and view all the answers

    What classification do Streptococcus pyogenes belong to?

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

    Which of the following pathogens is NOT typically associated with pneumonia?

    <p>Candida albicans</p> Signup and view all the answers

    What effect does the diphtheria toxin have on host cells?

    <p>Inhibits protein synthesis</p> Signup and view all the answers

    Which pathogen is primarily responsible for the common cold?

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

    Which organism is associated with Vincent's angina?

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

    Which of these pathogens can cause pharyngoconjunctival fever?

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

    What characterizes antigenic shift?

    <p>Reassortment of RNA segments</p> Signup and view all the answers

    Which of the following viruses undergoes antigenic drift?

    <p>Influenza A and B</p> Signup and view all the answers

    What is a common complication of influenza?

    <p>Reye’s syndrome</p> Signup and view all the answers

    How does oseltamivir function in influenza treatment?

    <p>Acts as a neuraminidase inhibitor</p> Signup and view all the answers

    What is required for the formulation of the new influenza vaccine each year?

    <p>Presence of the current strain in the vaccine</p> Signup and view all the answers

    What role do pigs play in the context of influenza virus variation?

    <p>They function as a 'mixing bowl' for different virus strains</p> Signup and view all the answers

    Which symptoms are specifically associated with influenza?

    <p>Severe myalgias and respiratory symptoms</p> Signup and view all the answers

    What distinguishes antigenic drift from antigenic shift?

    <p>Drift entails minor mutations whereas shift involves major changes</p> Signup and view all the answers

    What is the primary mechanism by which amantadine and rimantadine operate?

    <p>Inhibition of uncoating</p> Signup and view all the answers

    Which types of influenza are both amantadine and rimantadine effective against?

    <p>Influenza A only</p> Signup and view all the answers

    When should amantadine and rimantadine be administered for maximum effectiveness?

    <p>Within 48 hours of symptom onset</p> Signup and view all the answers

    What type of vaccine is a quadrivalent vaccine?

    <p>Contains two A strains and two B strains</p> Signup and view all the answers

    What is the main characteristic of the killed vaccine preparation?

    <p>Contains inactivated viral proteins</p> Signup and view all the answers

    What route of administration is primarily used for the live attenuated vaccine?

    <p>Intranasal spray</p> Signup and view all the answers

    What is a key feature of the live attenuated vaccine concerning temperature sensitivity?

    <p>Replicates in cooler nasal mucosa but not in the lungs</p> Signup and view all the answers

    Why are yearly boosters recommended for killed vaccines?

    <p>To maintain mucosal, humoral, and cell-mediated immunity</p> Signup and view all the answers

    Study Notes

    Respiratory Tract Infections Overview

    • Common respiratory tract infections include the common cold, croup, epiglottitis, pharyngitis, otitis media, bronchiolitis, and pneumonia.

    Important Pathogens by Disease

    • Common Cold: Caused by rhinoviruses and coronaviruses.
    • Croup: Primarily caused by parainfluenza virus.
    • Epiglottitis: Most commonly caused by Haemophilus influenzae type B.
    • Pharyngitis: Caused by Streptococcus pyogenes, Corynebacterium diphtheriae, and adenovirus (notable for pharyngoconjunctival fever).
    • Otitis Media: Caused by Streptococcus pneumoniae and Haemophilus influenzae.
    • Bronchiolitis: Primarily caused by respiratory syncytial virus (RSV).
    • Pneumonia: Caused by various bacterial, viral, and fungal pathogens.

    Pharyngitis Details

    • Definition: Inflammation of the throat, primarily due to viral infections.
    • Key Pathogens:
      • Viruses: Adenovirus, influenza virus, parainfluenza viruses, rhinoviruses, coronaviruses, and Coxsackie A virus.
      • Bacteria: Streptococcus pyogenes and Corynebacterium diphtheriae.
      • Fungi: Candida albicans, which can lead to oral thrush.

    Coxsackie Virus

    • Structure: Single-stranded, positive-sense RNA genome; nonenveloped with an icosahedral shape.
    • Classification: Divided into group A and group B.
    • Diseases (Group A):
      • Herpangina: Fever and sore throat with vesicles in the oropharynx.
      • Hand, foot, and mouth disease: Vesicular rash on hands and feet, ulcerations in the mouth, primarily affecting children.

    Corynebacterium diphtheriae

    • Characteristics: Gram-positive, club-shaped bacilli.
    • Virulence Factor: Produces diphtheria toxin, which inhibits protein synthesis leading to necrosis.
    • Clinical Manifestations: Causes local throat inflammation, thick gray pseudomembrane, sore throat, fever, and cervical adenopathy.
    • Complications: Can extend into the larynx causing airway obstruction, myocarditis, and cranial nerve paralysis.

    Laboratory Diagnosis of Diphtheria

    • Methods:
      • Throat swab specimen collection.
      • Direct smear revealing tapered Gram-positive bacilli.
      • Culture on Loeffler’s serum and blood tellurite medium.
      • Toxin production confirmed via Elek’s test or PCR for toxin gene presence.

    Treatment of Diphtheria

    • Diphtheria Antitoxin: Neutralizes unbound toxin in the bloodstream; potential for serum sickness and anaphylaxis.
    • Antibiotics: Penicillin G or erythromycin used to inhibit growth and reduce toxin production.

    Prevention of Diphtheria

    • Vaccination: Diphtheria toxoid combined with tetanus toxoid and pertussis vaccine (DPT).
    • Administered at 2, 4, and 6 months of age, prepared by inactivating the exotoxin with formaldehyde.

    Antigenic Variation

    • Antigenic Shift:
      • Major change due to reassortment of RNA genome segments; involves exchange of entire segments leading to new strains.
      • Pigs act as a mixing vessel for reassortment.
    • Antigenic Drift:
      • Minor changes due to mutations in the RNA genome; frequent occurrence, requiring annual updates to the flu vaccine.

    Influenza Pathogenesis and Clinical Manifestations

    • Transmission: Via respiratory droplets.
    • Symptoms: Severe myalgias and respiratory symptoms.
    • Complications: Risk of pneumonia (influenza or bacterial) and Reye’s syndrome.

    Drugs for Treatment and Prevention of Influenza

    • Oseltamivir and Zanamivir: Neuraminidase inhibitors that reduce virus spread if administered within 48 hours of onset.
    • Amantadine and Rimantadine: Act by inhibiting viral uncoating, effective only against influenza A. Resistance observed in avian and swine strains.

    Influenza Prevention

    • Immunization: Most reliable prevention method.
    • Vaccine Types:
      • Killed Vaccine: Contains purified protein subunits (hemagglutinin and neuraminidase); administered IM.
      • Live Attenuated Vaccine: Contains temperature-sensitive mutants; administered via nasal spray, offers short-lived protection.

    Annual Vaccination Strategy

    • Quadrivalent vaccine to include current strains of two A strains (H1N1, H3N2) and two B strains; reformulated yearly based on circulating strains.

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    Description

    This quiz provides an overview of common respiratory tract infections, their symptoms, and key pathogens associated with each illness. Learn about diseases such as the common cold, croup, and pneumonia, and understand the primary causes of these infections.

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