Otitis, sinusitis, diphtheria, pertussis

Question 1

Inflammation of the external auditory canal

Answer 1

otitis externa

Question 2

what is a major predisposing factor for otitis externa

Answer 2

moisture (swimmer’s ear)

Question 3

what are the most common causes of otitis externa

Answer 3

• pseudomonas aeruginosa
• staphylococcus aureus

Question 4

pseudomonas aeruginosa

• gram status
• shape
• form capsule?

Answer 4

• gram negative
• bacilli
• encapsulated

Question 5

pseudomonas aeruginosa produces what pigments

Answer 5

• pyocyanin: non-fluorescent bluish
  
  • many strains produce
• pyoverdin: fluorescent green
  
  • nearly all strains produce

Question 6

what function enables pseudomonas aeruginosa to produce pyocyanin and pyoverdin

Answer 6

• pyocyanin: generates ROS
• pyoverdin: sequesters iron (a siderophore)

Question 7

staphylococcus aureus

• gram status
• shape
• capsule?

Answer 7

• gram positive
• cocci in clusters
• encapsulated

Question 8

staphylococcus aureus: coagulase positive or negative

Answer 8

positive

Question 9

staphylococcus aureus: what happens when it is put on blood agar

Answer 9

B-hemolytic: the area appears lightened (yellow) and transparent.

Question 10

how is otitis externa diagnosed

Answer 10

• examination of ear
• gram stain

Question 11

treatment of otitis externa

Answer 11

• topical
  
  • acidifying agents
  • topical corticosteroids
• oral abx if fever is present

Question 12

what are the mot common bacterial causes of otitis media and sinusitis

Answer 12

• streptococcus pneumoniae (50%)
• haemophilus influenzae (20%)
• moraxella catarrhais (10%)

Question 13

inflammation of the middle ear, including tympanic membrane and usually associated with a buildup of fluid in the middle ear space

Answer 13

otitis media

Question 14

steptococcus pneuomonia

• gram status
• shape
• capsule?

Answer 14

• gram positive
• lancet-shaped diplococci
• virulent strains are encapsulated

Question 15

steptococcus pneuomonia has what two distinguishing factors on blood agar

Answer 15

• a-hemolysis
• sensitive to optochin

Question 16

Haemophilus influenzae

• gram status
• shape

Answer 16

• gram negative
• coccobacilli

Question 17

moraxella catarrhalis

• gram status
• shape

Answer 17

• gram negative
• diplococci

Question 18

moraxella catarrhalis has what distinguishing factors

Answer 18

• oxidase positive
• B-lactamase producer

Question 19

diagnosis of otitis media

Answer 19

clinical presentation

Question 20

DOC for acute bacterial otitis media

Answer 20

• amoxicillin
• chronic: tympanostomy tubes may be inserted

Question 21

diagnosis of sinusitis

Answer 21

• clinical presentation and history
• CT scan?

Question 22

causative agent of diphtheria

Answer 22

corynebacterium

Question 23

corynebacterium

• gram status
• shape
• requires oxygen?

Answer 23

• gram positive
• pleomorphic bacilli
• grows aerobically on blood agar

Question 24

which bacteria has a “Palisades,” “V,” “Chinese letters” appearance

Answer 24

corynebacterium

Question 25

what toxin does corynebacterium have

Answer 25

diphtheria toxin

Question 26

diphtheria toxin is what type of toxin

Answer 26

* A-B exotoxin * B: binding * A: catalytic

Question 27

diphtheria toxin MOA

Answer 27

* exotoxin binds to a heparin-binding EGF receptor * exotoxin is endocytosed and releases the A subunit * A subunit inactivates EF-2 via ADP-ribosylation, **halting protein synthesis**

Question 28

what are the two types of diphtheria

Answer 28

* cutaneous * respiratory

Question 29

what is cutaneous diphtheria

Answer 29

* chronic, nonhealing sores or ulcers * most cases are due to nontoxigenic strains

Question 30

presentation * pharyngeal colonization * sudden onset of malaise, exudative pharyngitis, low grade fever and lymphadenitis * formation of **pseudomembrane** * "bull neck" in serious disease

Answer 30

respiratory diphtheria

Question 31

what is the pseudomembrane of respiratory diphtheria consist of

Answer 31

* network of fibrin + bacteria + WBC + necrotic epithelial cells

Question 32

how is diphtheria transfered

Answer 32

**person to person** via respiratory droplets or skin contact

Question 33

where is diphtheria found

Answer 33

* worldwide, but uncommon is developed countries * vaccine use

Question 34

how is diphtheria diagnosed

Answer 34

* clinical examination * **pseudomembrane** * **bull neck**

Question 35

what cultures are used to diagnose diphtheria

Answer 35

* **Loeffler's medium**: supports growth and enhances formation of volutin granules * **cysteine-tellurite agar:** tests toxin production

Question 36

diptheria * gram status * shape * volutin

Answer 36

* gram positive * bacilli * metachromatic (volutin) granules

Question 37

what tests are used to diagnose diphtheria

Answer 37

* detect toxin production * Elek test * PCR * ELISA * immunochromatographic strip assay

Question 38

treatment of diphtheria

Answer 38

1. neutralize exotoxin : diphtheria antitoxin 2. Abx: DOC: erythromycin * prevention: vaccine * DTap, Tdap, Td

Question 39

what is the causative agent of whooping cough

Answer 39

* pertussis: Bordetella pertussis

Question 40

Bordetella pertussis * gram status * shape * require oxygen?

Answer 40

* gram negative * coccobacilli * grows aerobically on enriched agar

Question 41

What adhesins does Bordetella pertussis have

Answer 41

* filamentous hemagglutinin * agglutinogens

Question 42

Bordetella pertussis has what four exotoxins. what is the major one

Answer 42

* **pertussis toxin :A-B exotoxin** * adenylate cyclase toxin * dermonecrotic toxin * tracheal cytotoxin

Question 43

describe the catarrhal stage of pertussis disease

Answer 43

* inflammation of mucus membranes * presents as nonspecific URI * highly contagious

Question 44

describe the paroxysmal stage of pertussis disease

Answer 44

* paroxysmal coughing, often followed by vomiting "Whoop" (50/day) * 2-4 weeks * complications due to vomiting and increased pressure

Question 45

describe the convalescent stage of pertussis disease

Answer 45

* recovery * paroxysms decrease in number and severity * complications * PNA

Question 46

pertussis affects what species

Answer 46

strictly a human disease * highest incidence: children \< 1 yo

Question 47

pertussis is diagnosed using what cultures

Answer 47

* bordet-gengou agar * regan-lowe agar

Question 48

treatment of pertussis

Answer 48

DOC: erythromycin * prevention: immunization * DTap (series); Tdap (booster) * contain inactivated pertussis toxin and 1+ bacterial adhesins