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Questions and Answers
Which medium is NOT recommended for culturing the suspected organism in a case of diphtheria?
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?
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?
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?
Which of the following antibiotics is NOT indicated for the treatment of diphtheria?
What precaution should be taken when administering diphtheria antitoxin?
What precaution should be taken when administering diphtheria antitoxin?
What is the purpose of DPT vaccine administration in early childhood?
What is the purpose of DPT vaccine administration in early childhood?
How is diphtheria toxoid prepared?
How is diphtheria toxoid prepared?
What is a key characteristic of the Coxsackie virus?
What is a key characteristic of the Coxsackie virus?
At what ages is the DPT vaccine administered to children?
At what ages is the DPT vaccine administered to children?
What disease is associated with Group A Coxsackie virus?
What disease is associated with Group A Coxsackie virus?
Which of the following is a virulence factor of Corynebacterium diphtheriae?
Which of the following is a virulence factor of Corynebacterium diphtheriae?
What complication can arise from Corynebacterium diphtheriae infection?
What complication can arise from Corynebacterium diphtheriae infection?
Which pathogen is the most common cause of epiglottitis?
Which pathogen is the most common cause of epiglottitis?
Which symptom is NOT associated with herpangina caused by Coxsackie virus?
Which symptom is NOT associated with herpangina caused by Coxsackie virus?
What is the primary cause of pharyngitis?
What is the primary cause of pharyngitis?
In which tissue does adenovirus typically establish latent infection?
In which tissue does adenovirus typically establish latent infection?
Which virus is primarily responsible for bronchiolitis?
Which virus is primarily responsible for bronchiolitis?
What type of organism is Corynebacterium diphtheriae classified as?
What type of organism is Corynebacterium diphtheriae classified as?
What classification do Streptococcus pyogenes belong to?
What classification do Streptococcus pyogenes belong to?
Which of the following pathogens is NOT typically associated with pneumonia?
Which of the following pathogens is NOT typically associated with pneumonia?
What effect does the diphtheria toxin have on host cells?
What effect does the diphtheria toxin have on host cells?
Which pathogen is primarily responsible for the common cold?
Which pathogen is primarily responsible for the common cold?
Which organism is associated with Vincent's angina?
Which organism is associated with Vincent's angina?
Which of these pathogens can cause pharyngoconjunctival fever?
Which of these pathogens can cause pharyngoconjunctival fever?
What characterizes antigenic shift?
What characterizes antigenic shift?
Which of the following viruses undergoes antigenic drift?
Which of the following viruses undergoes antigenic drift?
What is a common complication of influenza?
What is a common complication of influenza?
How does oseltamivir function in influenza treatment?
How does oseltamivir function in influenza treatment?
What is required for the formulation of the new influenza vaccine each year?
What is required for the formulation of the new influenza vaccine each year?
What role do pigs play in the context of influenza virus variation?
What role do pigs play in the context of influenza virus variation?
Which symptoms are specifically associated with influenza?
Which symptoms are specifically associated with influenza?
What distinguishes antigenic drift from antigenic shift?
What distinguishes antigenic drift from antigenic shift?
What is the primary mechanism by which amantadine and rimantadine operate?
What is the primary mechanism by which amantadine and rimantadine operate?
Which types of influenza are both amantadine and rimantadine effective against?
Which types of influenza are both amantadine and rimantadine effective against?
When should amantadine and rimantadine be administered for maximum effectiveness?
When should amantadine and rimantadine be administered for maximum effectiveness?
What type of vaccine is a quadrivalent vaccine?
What type of vaccine is a quadrivalent vaccine?
What is the main characteristic of the killed vaccine preparation?
What is the main characteristic of the killed vaccine preparation?
What route of administration is primarily used for the live attenuated vaccine?
What route of administration is primarily used for the live attenuated vaccine?
What is a key feature of the live attenuated vaccine concerning temperature sensitivity?
What is a key feature of the live attenuated vaccine concerning temperature sensitivity?
Why are yearly boosters recommended for killed vaccines?
Why are yearly boosters recommended for killed vaccines?
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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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