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Upper Respiratory Infections Overview
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Upper Respiratory Infections Overview
Upper Respiratory Infections Overview
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1
Question
What are the expected learning outcomes by the end of the lecture on Upper Respiratory Tract Infections?
Answer
Students should be able to: Identify species of the Corynebacterium genus; Discuss the mode of transmission, pathogenesis, virulence factors, culture characteristics, growth requirements, laboratory diagnosis, treatment, and prevention of Corynebacterium diphtheriae; Discuss the morphology, culture characteristics, growth requirements, pathogenesis, laboratory diagnosis, prevention, and treatment of Haemophilus influenzae; Describe the characteristic features, pathogenesis, laboratory diagnosis, and treatment of Pseudomonas aeruginosa; Describe the characteristic features, pathogenesis, laboratory diagnosis, and treatment of viral causes of upper respiratory tract infections.
2
Question
What is the main virulence factor of Corynebacterium diphtheriae?
Answer
The main virulence factor of C. diphtheriae is the Diphtheria Exotoxin.
3
Question
What factors influence the production of Diphtheria exotoxin?
Answer
1. Presence of a lysogenic prophage carrying the toxin gene. 2. Low extracellular concentration of iron.
4
Question
How does Diphtheria exotoxin affect the body?
Answer
Diphtheria exotoxin acts by inhibiting protein synthesis, causing cell death, especially in cardiac muscle and cranial peripheral nerves.
5
Question
What are the modes of transmission for Diphtheria?
Answer
Diphtheria is transmitted via droplets from infected individuals or carriers.
6
Question
What are the characteristic features of pharyngeal or tonsillar Diphtheria?
Answer
Commonest form with pseudomembrane formation, enlarged cervical lymph nodes, bull neck, and low-grade fever.
7
Question
What is the clinical diagnosis process for Diphtheria?
Answer
Clinical diagnosis is very important. Once clinically suspected, antitoxin and antibiotics should be immediately initiated without awaiting laboratory diagnosis.
8
Question
What is the first step in the microbiological diagnosis of Diphtheria?
Answer
Isolation of C. diphtheriae and detection of the toxin.
9
Question
What is the recommended treatment of Diphtheria?
Answer
1. Diphtheria antitoxin. 2. Antibiotics such as Penicillin or Erythromycin.
10
Question
What is the vaccination schedule for Diphtheria?
Answer
Diphtheria toxoid is given IM at 2, 4, 6, and 18 months, usually together with tetanus toxoid and pertussis vaccine in a DPT booster dose at school entry (6 years), followed by a Td booster every 10 years.
11
Question
What are the medically important species of the Haemophilus genus?
Answer
The medically important species include H. influenzae, H. ducreyi, and H. aegyptius.
12
Question
What are the characteristic features of Haemophilus influenzae?
Answer
Gram-negative pleomorphic bacilli, facultative anaerobes, and some strains have a polysaccharide capsule.
13
Question
What growth factors are required for Haemophilus influenzae?
Answer
H. influenzae requires both X (haemin) and V (NAD) factors for growth.
14
Question
What is the common mode of transmission for H. influenzae?
Answer
H. influenzae is transmitted by respiratory droplets.
15
Question
What are the virulence factors of H. influenzae?
Answer
1. Polysaccharide capsule (divides H. influenzae into six serotypes a-f, where type b causes most severe invasive diseases). 2. IgA protease.
16
Question
What are the laboratory diagnosis methods for H. influenzae infection?
Answer
1. Gram-stained smear. 2. Quellung reaction. 3. PCR. 4. Cultivation on chocolate agar.
17
Question
What is the treatment of choice for Haemophilus influenzae infection?
Answer
Third generation cephalosporins such as cefotaxime or ceftriaxone.
18
Question
What is the primary prevention method for Haemophilus influenzae type B infection?
Answer
Haemophilus influenzae type B (Hib) vaccine.
19
Question
What are the characteristics of Pseudomonas aeruginosa?
Answer
Aerobic, motile, non-fermentative Gram-negative bacilli, produces green exopigments, and is found in moist body sites and hospital environments.
20
Question
What are the significant diseases caused by Pseudomonas aeruginosa?
Answer
Pneumonia, external ear infections (swimmer's ear), folliculitis, wound infections, urinary tract infections, and eye infections.
21
Question
What is the recommended treatment approach for serious infections caused by Pseudomonas aeruginosa?
Answer
Combined antibiotic treatment, e.g., anti-pseudomonal beta-lactam (piperacillin) plus an aminoglycoside (gentamycin).
22
Question
What viruses are commonly involved in upper respiratory tract viral infections?
Answer
Rhinoviruses, Adenoviruses, Cytomegalovirus (CMV), Epstein-Barr virus (EBV), and Human Immunodeficiency Virus (HIV).
23
Question
What is the most common mode of transmission for the common cold viruses?
Answer
Direct and indirect contact, as well as droplet transmission.
24
Question
What are the complications associated with Rhinovirus infections?
Answer
Secondary bacterial infections resulting in otitis media, sinusitis, bronchitis, and bronchopneumonia, especially in children.
25
Question
What is the structure of adenoviruses?
Answer
Non-enveloped dsDNA viruses with icosahedral symmetry and fibers protruding from the capsid.
26
Question
What are the diseases caused by adenoviruses?
Answer
Respiratory diseases, eye infections, gastrointestinal diseases, acute hemorrhagic cystitis, and meningitis.
27
Question
What is the mode of transmission for Epstein-Barr virus (EBV)?
Answer
Intimate contact with saliva, often referred to as the kissing disease.
28
Question
What are the clinical features of Infectious Mononucleosis (Glandular Fever)?
Answer
Incubation period of 4-7 weeks, fever, sore throat, skin rash, cervical lymphadenopathy, and hepatosplenomegaly.
29
Question
What laboratory methods are used to diagnose Infectious Mononucleosis?
Answer
1. Blood picture showing high total leucocytic count with atypical lymphocytes. 2. Detection of heterophil antibodies.
30
Question
What is the Paul Bunnell test or monospot test used for?
Answer
It is used for the detection of EBV (Epstein-Barr Virus) specific antibodies.