Chapter 24: Microbial Diseases of the Respiratory System

Question 1

Give the etiological agents for otitis media.

Answer 1

a. S. pneumoniae (35%)
b. H. influenzae (20–30%)
c. M. catarrhalis (10–15%)
d. S. pyogenes (8–10%)
e. S. aureus (1–2%)
f. Incidence of S. pneumoniae reduced by vaccine
g. Often results from complication of nose and throat infections
h. Pus formation builds up pressure against the eardrum causing pain

Question 2

List tools used in the diagnosis of strep throat.

Transmitted via respiratory route

Answer 2

a. Caused by S. pyogenes- Beta- hemolytic group A streptococcus
i. Resistant to phagocytosis
ii. Produces streptokinases (lyses clots), DNAse and hemolysins

c. Signs include inflammation and fever
d. Tonsilitis and otitis media may occurr
e. Diagnosis include indirect agglutination tests and FA
f. Immunity does not develop usually
g. Also known as Streptococcal Pharyngitis

Question 3

list differences between mycoplasmal pneumonia and viral pneumonia

Answer 3

a. Myclosplasma pneumoniae
i. Symptoms: Mild but persistent respiratory symptoms; low fever, cough, headache
ii. Diagnosis: PCR and serological testing
iii. Treatment: Tetracyclines

b. Viral Pneumonia
i. Etiology is usually not demonstrated
ii. Often occurs as a complication of viral infections such as influenza
iii. Laboratory diagnosis is usually not done
iv. RSV- Respiratory Syncytial virus is the most common cause of pneumonia
v. Influenza virus can also be associated

Question 4

List all the etiologic agents for pneumonia

Answer 4

table

Question 5

List the pros and cons of the tuberculin test

Answer 5

a. Tuberculin test is used to determine exposure to TB
b. Not diagnostic because false positive results may indicate an active case, previous infection or vaccination and immunity
c. Followed by X-ray or CT exam, acid-fast staining of sputum, culturing of bacteria
d. Diagnosis is based on isolation and identification and takes a very long time

Question 6

list opportunistic pathogens in AIDS patients

Answer 6

a. Aspergillus fumigatus
b. Mucor
c. Rhizopus
table 19.5

Question 7

Give the mode of transmission for Legionella.

Answer 7

a. Legionella pneumophila is a Gram-negative rod found in water
b. Transmitted by inhaling aerosols; not transmitted from human to human
c. Associated with legionellosis

Question 8

Give sypmtoms, diagnosis, and treatment of Legionella.

Answer 8

Symptoms: Potentially fatal pneumonia that tends to affect older men who drink or smoke heavily

ii. Diagnosis: Culture on selective media, DNA probe
iii. Treatment: Erythromycin