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Microbiology Test II > Otitis, Sinusitis, Diphtheria & Pertussis > Flashcards

Otitis, Sinusitis, Diphtheria & Pertussis Flashcards

1
Q

Otitis externa bacterial causes

A

Pseudomonas aeruginosa

Staphylococcus aureus

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2
Q

Otitis media and Sinusitis bacterial causes

A

Streptococcus pneumonia
Moraxella catarrhalis
Haemophilus influenze

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3
Q

Diptheria bacteria

A

Corynebacterium diphtheriae

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4
Q

Whooping cough (Pertussis) bacteria

A

Bordatella pertussis

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5
Q

Otitis Externa predisposing factors

A

MOISTURE (swimmer’s ear), insertion of foreign objects, trauma, chronic skin diseases

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6
Q

What is otitis externa?

A

inflammation of the external auditory canal

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7
Q

Otitis Externa: characteristic presenting signs/symptoms

A

OTALGIA and OTORRHEA

fever >38.3*C indicates more than localized involvement

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8
Q

Most common bacterial causes of otitis external

A

Pseudomonas aeruginosa

Staphylococcus aureus

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9
Q

Pseudomonas aeruginosa (cause of, imp features)

A 
bacterial cause of OTITIS EXTERNA
gram NEGATIVE
BACILLI
encapsulated
pigment producer (pyocyanin-nonfluorescent blue; pyoverdin-fluorescent green)
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10
Q

Pyocyanin

A
  1. NON-fluorescent bluish pigment (produced by Pseudomonas aeruginosa)
  2. generates ROSs (reactive oxygen species)
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11
Q

Pyoverdin

A
  1. FLUORESCENT green pigment (produced by Psuedomonas aeruginosa)
  2. Sequesters iron (a siderophore)
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12
Q

Pseudomonas aeruginosa pigments

A

many produce pyocyanin

nearly all produce pyoverdin

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13
Q

Staphylococcus aureus (cause of, imp features)

A 
bacterial cause of OTITIS EXTERNA
gram-POSITIVE
encapsulated
COAGULASE POSITIVE
BETA-HEMOLYTIC
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14
Q

Otitis Externa diagnosis

A
  • Examination of ear

- Gram stain (neg=P. aegurinosa, pos.=S. aureus)

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15
Q

Otitis externa tx

A
  • remove debris from ear canal
  • TOPICAL TX: acidifying agent, top. corticosteroid, top antimicrobial agents
  • if fever is present or disease is extended, oral antibiotics
  • systemic analgesics
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16
Q

What is otitis media?

A

inflammation of MIDDLE EAR, including tympanic membrane & usually a/w buildup of fluid in middle ear space

17
Q

what is sinusistis?

A

inflammation w/in PARANASAL SINUSES; may or may no be purulent

18
Q

Most common BACTERIAL causes of otitis media and sinusitis (w/percentages)

A 
Streptococcus pneumonia (~50%)
Haemophilus influenza (~20%)
Moraxella catarrhalis (~10%)
19
Q

Streptococcus pneumonia (cause of, features)

A 
OTITIS MEDIA, SINUSITIS (~50% of bac inf)
gram POSITIVE, LANCET-shaped, DIPLOCOCCI
virulent strains are encapsulated
ALPHA-HEMOLYSIS on blood agar
SENSITIVE TO OPTOCHIN
20
Q

Haemophilus influenza (cause of, features)

A

OTITIS MEDIA, SINUSITIS (~20% of bac inf)
gram NEGATIVE
COCOBACILLI
nontypable strains

21
Q

Moraxella catarrhalis (cause of, features)

A

OTITIS MEDIA, SINUSITIS (~10% of bac inf)
GRAM NEGATIVE
OXIDASE POSITIVE
Beta-lactamase producer

22
Q

Otitis Media: how to dx?

A

CLINICAL PRESENTATION

reserved for restricted patient pops: tympanocentesis to aspirate fluid from middle ear, culture and gram stain

23
Q

Otitis Media Treatment

A

if BACTERIAL acute otitis media (AOM) is suspected, antibiotics can be prescribed
DOC for AOM: amoxicillin (but choice depends on many factors)
in CHRONIC cases, tympanostomy tubes may be inserted

24
Q

Sinusitis: how to dx?

A
  • CLINICAL PRESENTATION and HISTORY is most common
  • nasal cytology (biopsy)
  • CT scan, allergy testing
25
Q

sinusitis tx

A

VARIES based on type of sinusitis and offending agent (allergen, smoke, pathogen, etc.)

  • nasal irrigation
  • analgesics
  • OTC decongestants
  • antibiotics
  • nasal steroids
  • nasal surgery
26
Q

Diptheria causative agent

A

Corynebacterium diphtheria

27
Q

Corynebacterium (causes what?, features)

A 
Diptheria
gram-POSITIVE PLEOMORPHIC BACILLI
"Chinese letters" appearancBe
Metachromatic (volutin) granules
grows AEROBICALLY on BLOOD AGAR
toxigenic strains have phage-exotoxin=DIPTHERIA TOXIN
28
Q

Diptheria toxin: what stimulates its production?

A

low iron concentration stimulates production of diphtheria toxin

29
Q

Diptheria toxin: what kind of toxin is it?

A

A-B exotoxin
B=receptor binding domain
A=catalytic subunit

30
Q

Diptheria toxin: how does it work?

A

B (receptor binding domain) binds to a heparin-binding EGF receptor
-exotoxin in endocytosed
-vesicle acidifies, releasing the A subunit and allowing it to move into the cytosol
A (catalytic subunit) inactivates EF-2 via ADP-ribosylation, HAULTING PROTEIN SYNTHESIS

31
Q

Cutaneous diphtheria (characteristics, cause)

A
  • characterized by chronic, nonhealing sores or ulcers

- most cases are due to nontoxigenic strains of Corynebacterium diphtheriae

32
Q

Pseudomembrane: what is in it

A

pseudomembrane=network of fibrin + bacteria + WBCs + necrotic epithelial cells

33
Q

Respiratory diphtheria (what happens, what sxs and signs)

A
  • pharyngeal colonization
  • sudden onset of malaise, exudative pharyngitis, low-grade fever, lymphadenitis
  • formation of pseudomembrane
  • “bull neck” in serious disease
  • systemic complications
34
Q

Diphtheria pathogenesis

A
  1. Adherence and proliferation (2-6 days)
  2. Localized damage due to exotoxin (inhibition of protein synthesis and cell death) leads to:
    a. local necrosis and edema (thick grayish to black pseudomembrane and bull neck)
    b. continued exotoxin production->systemic toxicity (mycorditis and demyelination)
35
Q

Diphtheria epi: where is it found, how is it spread, etc

A

found worldwide, esp in POOR URBAN AREAS where vaccine-induced immunity is low
(UNCOMMON in developed cntries-vaccine)
-maintained in pop by asymptomatic carriage in immune ppl.
PERSON-TO-PERSON SPREAD via respiratory droplets or skin contact
REPORTABLE in the us (respiratory diphtheria)

36
Q

Diphtheria clinical exam

A

CLINICAL EXAMINATION is most imp for early dx to allow initiation of appropriate treatment
formation of PSEUDOMEMBRANE
BULL NECK in serious disease

37
Q

Diphtheria dx staining

A

Gram: club-shaped, GRAM-POSITIVE BACILLI
Volutin: metachromatic (volutin granules)

Microbiology Test II (2 decks)

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