Upper Respiratory Infections

Front 1

What do most cystic fibrosis patients die from?

Back 1

Secondary pathogens:

Pseudomonas pneumoniae

Front 2

Which bacteria are increased following antibiotic therapy?

Back 2

C. albicans

Pseudomonas

E. coli

Front 3

Following hospitalization, _________ decreases, producing an increase in gram negative bugs.

Back 3

fibronectin

Front 4

Community acquired pneumonias are generally associated with which gram stain?

Back 4

Gram positive

Front 5

What are most upper respiratory infections caused by?

Back 5

Viruses

Front 6

Bacterial causes of acute pharyngitis include which organisms?

Back 6

S. pyogenes

H. influenzae

C. diphtheriae

N. gonorrheae

Front 7

Strep throat is most commonly caused by which organisms?

What are its characteristics?

Back 7

Streptococcus pyogenes

Group A β-hemolytic streptococci

Front 8

What are the characteristic features of Group A strep?

Back 8

Gram positive cocci, grow in chains

most facultative anaerobes, β-hemolytic

catalase negative, non spore-forming

Front 9

What is the most common cause of bacterial tonsillopharyngitis?

Back 9

Group A strep

(S. pyogenes)

Front 10

What are the clinical complications/manifestations of Group A Strep?

Back 10

Sinusitis, otitis media, meningitis, scarletina, erysipelas, cellulitis

Front 11

What are the virulence factors for Group A Strep?

Back 11

Capsule (hyaluronic acid)

M protein

Hemolysins: streptolysin O and streptolysin S

Enzymes

SPEs (Strep pyrogenic exotoxins)

Front 12

What is the function of streptolysin O?

Back 12

Hemolyzes RBCs

Antigenic, thus used clinically

Front 13

What is the function of streptolysin S?

Back 13

Damages membranes of neutrophils, platelets, etc.

Front 14

What are the sequelae of Group A Strep infections?

Back 14

Rheumatic Heart Disease

Acute Rheumatic Fever

Antibodies against Group A carbohydrates react with heart valves

Front 15

What are Aschoff bodies?

Back 15

Pathognomonic for Rheumatic Carditis

Nidus of macrophages with adjoining lymphocytes are fibrosis

Front 16

What are the characteristics of H. influenzae?

Back 16

Small, non-motile, gram negative

Coccobacilli or pleomorphic bacilli

Common colonizers of URT (~50%)

Front 17

Encapsulated type b strains of H. influenza cause which potentially life threatening infections?

Back 17

Meningitis and epiglottitis

Front 18

Nonencapsulated or nontypable strains of H. influenzae cause which local infections?

Back 18

Pharyngitis and otitis media

Front 19

What are the virulence factors for H. influenzae?

Back 19

Polysaccharide capsule - avoids phagocytosis and complement

Capsule is a polymer of polyribitol phosphate (PRP)

IgA protease production

Endotoxin (LPS)

Front 20

Which enzyme do many virulent organisms produce?

Back 20

IgA protease

Front 21

What factors are required for the growth of H. influenzae?

Back 21

X factor = hemin

V factor = NAD

Chocolate agar (lysed RBCs)

Front 22

At what age range is the incidence of H. influenzae infection the highest?

Back 22

6-18 months

Front 23

Corynebacterium diphtheriae

Back 23

Causes Diphtheria ("leather hide")

Gram positive, catalase positive

Non-encapsulated, non-motile, pleomorphic

Club-shaped, slender rod

Requires potassium tellurite

Front 24

To which bacterium are humans the only reservoir?

Back 24

C. diphtheriae

Front 25

What is pathognomoic for Corynebacterium infection?

Back 25

Bloody tears due to torn corneal pseudomembrane

Front 26

What are the virulence factors of Diphtheria?

Back 26

Toxin mediated disease of URT

Toxin produced by bacteriophage gene

Exotoxin - "A" fragment inactivates elongation factor 2 (EF2)

Front 27

What are some of the organisms that cause sinusitis?

Back 27

S. pneumoniae (MCC)

Haemophilus influenzae

Moraxella cararrhalis

Aspergillus

Front 28

What are the characteristics of Streptococcus pneumoniae?

Back 28

Gram positive, lancet-shaped diplococci, catalase negative

α-hemolysis, pathogenic strains encapsulated

Front 29

What are the virulence factors of S. pneumoniae?

Back 29

Polysaccharide capsule

Pneumolysin - activates/uses up complement

Phosphorylcholine

IgA protease

Front 30

What are the characteristics of Moraxella catarrhalis?

Back 30

Gram negative diplococci

Aerobic and oxidase + (like Neisseria & Pseudomonas)

Front 31

What are the risk factors for sinusitis?

Back 31

URI, dental infection, CFTR mutations, allergies, nasal polyps, smoking in household, structural problems (deviated septum, small ostia)

Front 32

What are the risk factors for otitis media?

Back 32

young age, viral URIs, low angle of eustachian tube, daycare, bottlefeeding, smoking in household, prematurity, GERD, cleft palate

Front 33

What is the most common mechanism for sinusitis and otitis media?

Back 33

Usually secondary to a viral URI (rhinovirus, coronavirus, adenovirus)

Mucosal sweeling obstructs outflow tract of sinus/eustachian tube

URI impairs mucociliary clearance and overproduction of secretions

Negative pressure in middle ear, serous fluid, is an ideal bacterial medium

Front 34

What is the treatment for sinusitis/otitis media?

Back 34

"watchful waiting" - due to the fact that most are viral infections

Front 35

What are the risk factors for otitis externa?

Back 35

excess moisture or cerumen in canal, trauma, foreign bodies, eczema, swimmers/divers, hearing aid use

Front 36

What are the clinical symptoms of otitis externa?

Back 36

Progressive ear pain (unilateral)

History of exposure to water

Purulent discharge

Conductive hearing loss

Front 37

What is the most common cause of otitis externa?

Back 37

Pseudomonas

Front 38

What is the most common of otitis externa due to fungi?

Back 38

Aspergillus

Front 39

What is the most common cause of malignant otitis externa?

Back 39

Pseudomonas

Front 40

What are the characteristic features of Bordetella pertussis?

Back 40

Gram negative, pleomorphic coccobacilli, strict aerobes

Humans are the only reservoir

Causes whooping cough

Front 41

What is the pathophysiologic mechanism of whooping cough?

Back 41

B. pertussis bacilli attach to respiratory epithelium via hemagglutinins, A-B toxin causes:

ADP-ribosylation of Gi protein (irreversibly inactivates, thus increasing cAMP)

Result: inhibition of phagocytosis of infected ciliated epithelial cells

Front 42

What are the clinical characteristics of whooping cough?

Back 42

Tracheobronchitis - leads to paroxysms of cough following by inspiratory whoops, emesis or seizure

Front 43

How is a B. pertussis infection diagnosed?

Back 43

Strong clinical suspicion

Lymphocytosis on CBC

Front 44

What are the bacterial agents that cause lymphocytosis?

Back 44

TB, Brucella, Bordetella