1 Otitis Sinusitis Dip And Whoop

Question 1

Inflammation of the external auditory canal

Answer 1

Otitis Externa

Question 2

Predisposing factors for otitis externa

Answer 2

Moisture (swimmer’s ear)

Insertion of foreign objects

Trauma

Chronic skin diseases

Question 3

Characteristic SSx of otitis externa

Answer 3

Otalgia and otorrhea

Question 4

A fever of > 38.3˚C accompanying otitis externa indicates…

Answer 4

More than localized involvement

If it’s only otitis externa, you won’t typically see a fever

Question 5

Most common bacterial causes of otitis externa

Answer 5

Pseudomonas aeruginosa
Staphylococcus aureus

Both are predominant parts of normal skin flora

Question 6

Characteristic of pseudomonas that protects it from ID by the immune system

Answer 6

SLIME LAYER

It’s encapsulated and glycocalyx gives the immune system the slip

Question 7

Describe pseudomonas

Answer 7

Gram-negative bacilli

Encapsulated

Pigment producer

Question 8

What are these pigments that pseudomonas makes?

Answer 8

Pyocyanin - non-fluorescent bluish; it’s a virulence factor (generates ROSs to kill off its competition and body tissue with it)

Pyoverdin - fluorescent green; not really a virulence factor but makes it easier to ID (sequesters iron - a siderophore)

Question 9

What does pseudomonas smell like?

Answer 9

Very distinct fruity odor (no other organism smells like it)

Question 10

Describe staphylococcus aureus

Answer 10

Gram-positive cocci in graphlike clusters

Encapsulated

Coagulate positive

ß-hemolytic version leads to complete lysis of RBCs
• Quick test - can cause blood clots via enzyme - other staph orgs don’t

Question 11

How do you diagnose otitis externa?

Answer 11

Examination of the ear

Gram stain

Question 12

Treatment of otitis externa

Answer 12

Removal of debris from the ear canal

Topical treatments: acidifying agents, topical corticosteroids, topical antimicrobial agents

Oral abx if fever is present or extension of disease has occurred

Systemic analgesics

Question 13

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

Answer 13

Otitis media

Question 14

Inflammation within the paranasal sinuses; may or may not be purulent

Answer 14

Sinusitis

Question 15

Most common bacterial causes of otitis media and sinusitis

Answer 15

Streptococcus pneumoniae (~50%)

Haemophilus influenzae (~20%)

Mortadella catarrhalis (~10%)

Question 16

Streptococcus pneumoniae has what shape/stain?

Answer 16

Gram-positive, lancet-shaped diplococci

Question 17

Virulent strains of strep pneumo are _______

Answer 17

Encapsulated

Question 18

Alpha-hemolysis on blood agar is indicative of what bacterium?

Answer 18

Strep pneumo

Can lyse RBCs but not completely like ß-hemolytic bacteria

Question 19

Bacterium that is sensitive to optochin

Answer 19

Strep pneumo

Optochin is an abx used for Dx only (too toxic for therapeutic use)

Optochin helps us differentiate strep pneumo from other strains of strep

Question 20

What does Haemophilus influenzae look like?

Answer 20

Gram-negative coccobacilli

Some non-typeable strains

Question 21

What does Moraxella catarrhalis look like?

Answer 21

Gram-negative diplococci

Question 22

Moraxella catarrhalis virulence factors

Answer 22

Oxidase positive

ß-lactamase producer

Question 23

How is Otitis Media diagnosed?

Answer 23

Clinical presentation

Tympanocentesis to aspirate fluid from middle ear CAN be done but usually reserved for restricted patient populations

Question 24

DOC for AOM

Answer 24

Amoxicillin

However, several antibiotics are available - choice depends on several factors

In chronic cases, may insert tympanostomy tubes

Question 25

How is sinusitis diagnosed?

Answer 25

Clinical presentation and history most common Can also do nasal cytology (biopsy), CT scan, allergy testing (but usually not necessary)

Question 26

Treatment of sinusitis

Answer 26

Varies depending on the type of sinusitis and the offending agent ``` Nasal irrigation Analgesics OTC decongestants Abx Nasal steroids Nasal surgery ```

Question 27

Causative agent of Diphtheria

Answer 27

Corynebacterium Gram-positive, pleomorphic bacilli (shape different depending on where it’s growing)

Question 28

Special features of corynebacterium

Answer 28

Palisades or “V” appearance Metachromatic volition granules (polar ends) Grows aerobically on blood agar but usually cultured on selective media

Question 29

Toxigenic strains of corynebacterium have...

Answer 29

A phage-encoded exotoxin (diphtheria toxin)

Question 30

What stimulates the production of diphtheria toxin?

Answer 30

Low iron concentration

Question 31

How does Diphtheria toxin function?

Answer 31

Low iron concentration stimulates production of diphtheria toxin, which is an A-B exotoxin Exotoxin binds to a heparin-binding EGF receptor, exotoxin is endocytosed, vesicle acidified, releasing the A subunit and allowing it to move into the cytoskeleton, where it inactivates EF-2 via ADP-ribosylation —> halting protein synthesis

Question 32

Cutaneous diphtheria is characterized by...

Answer 32

Chronic, non-healing sores or ulcers Most cases are due to nontoxigenic strains of corynebacterium

Question 33

Respiratory diphtheria is characterized by...

Answer 33

Pharyngeal colonization Sudden onset of malaise, exudative pharyngitis, low-grade fever, and lymphadenitis Formation of PSEUDOMEMBRANE (network of fibrin+bacteria+WBCs+necrotic epithelial cells) —> local tissue destruction “Bull neck” in serious disease Systemic complications

Question 34

Pathogenesis of diphtheria

Answer 34

Adherence and proliferation + 2-6 days Localized damage due to exotoxin Continued exotoxin production Systemic toxicity (myocarditis and demyelination) Local necrosis and edema (pseudomembrane and bull neck)

Question 35

Diphtheria is found worldwide but especially in...

Answer 35

Poor urban areas where vaccine-induced immunity is low Maintained in the population by asymptomatic carriage in immune individuals Person-to-person spread via respiratory droplets or skin contact

Question 36

Is diphtheria a reportable disease?

Answer 36

Yes (respiratory is anyway) Vaccines have made it uncommon in developed countries these days

Question 37

How is diphtheria diagnosed?

Answer 37

Clinical examination is most important for early diagnosis to allow initiation of appropriate treatment PSEUDOMEMBRANE BULL NECK

Question 38

What culture media are used to diagnose diphtheria?

Answer 38

Loeffler’s medium (supports growth and enhances formation of volutin granules) Cysteine-tellurite agar (distinctive black to tellurite reduction, isolates tested for toxin production)

Question 39

How does diphtheria stain?

Answer 39

Gram-positive bacilli with metachromatic volutin granules

Question 40

What is the Elek test?

Answer 40

Immunodiffusion assay to secretion of diphtheria exotoxin

Question 41

What other methods are used to diagnose diphtheria

Answer 41

Various methods for isolating toxin production Elek test PCR (expensive) - detects tox gene ELISA (also $$) - detects diphtheria exotoxin Immunochromatographic strip assay - detects diphtheria exotoxin

Question 42

Treatment of diphtheria is focused on ...

Answer 42

Neutralizing exotoxin Administration of diphtheria antitoxin requires rapid diagnosis and treatment

Question 43

What antibiotic is used against diphtheria?

Answer 43

DOC = erythromycin (alternative = penicillin) Isolation to minimize secondary spread

Question 44

Causative agent of pertussis

Answer 44

Bordatella pertussis Small, gram-negative coccobacilli Grows aerobically on enriched agar

Question 45

Virulence factors for bordatella pertussis

Answer 45

Several in addition to endotoxins Adhesins mediate attachment of integrity’s and subsequent colonization of the ciliated respiratory epithelium 4 exotoxins: Pertussis toxin (A-B exotoxin) Dermonecrotic toxin (vasoconstriction —> ischemic necrosis) Adenylate cyclase toxin (decreases chemostasis) Tracheal cytotoxic (kills ciliated respiratory epithelial cells, stimulates IL-1 release)

Question 46

Pathogenesis of pertussis

Answer 46

Inhalation of aerosol droplets Bacterial attachment to ciliated airway epithelium and production of toxins Bacterial multiplication, influx of neutrophils, damage to ciliated epithelium by TCT and LPS, music hypersecretion Compromises the small airways and predisposes patients to atelectasis, cough, cyanosis, and PNA

Question 47

Average incubation period for pertussis

Answer 47

7-10 days

Question 48

Most highly contagious stage of pertussis

Answer 48

Catarrhal stage (1-2 weeks after incubation) Inflammation of the mucous membranes, presents as nonspecific upper respiratory tract syndrome with insidious onset

Question 49

Second stage of pertussis

Answer 49

Paroxysmal stage (2-4 weeks) Attacks or spasms of paroxysmal coughing often with posttussive emesis This is when you’ll hear the characteristic “whoop” due to labored inspiration

Question 50

Third stage of pertussis

Answer 50

Convalescent stage - paroxysms decrease in number and severity with gradual recovery over several weeks Serious complications can develop (PNA, encephalopathy, seizures, death)

Question 51

Presumptive diagnosis of pertussis is via

Answer 51

Serology ELISA to detect Ig to pertussis toxins or adhesins 4-fold increase in paired sera or a high initial titer is indicative of a recent infection

Question 52

Definitive diagnosis of pertussis is via...

Answer 52

Culture on an enriched medium: • Bordet-Gengou agar • Regan-Lowe agar Can also use PCR (highly sensitive)

Question 53

Treatment of pertussis

Answer 53

DOC = erythromycin or other macrolide Alternative: TMP-SMX Can also give prophylaxis for nonimmunized contacts Prevention via immunization (DTaP or Tdap booster)