Prunuske -- Otitis Media Flashcards
Otitis externa
external otic canal infection
Otitis media
middle ear canal infection
Labrinthitis
inner ear infection
Mastoiditis
mastoid bone infection
Otitis media with effusion
build up of fluid in Eustachian tube
Acute otitis media
bacterial or viral
pain, red ear drum, pus, and fever
~70% of children experience at least 1 episode of otitis media during childhood probably b/c tubes are more narrow and horizontal and 1/3 have had 3 or more episodes
More common in males and Native American/Alaskan Natives
Common etiologic agents of acute otitis media
Streptococcus pneumoniae: 25-50%
Haemophilus influenzae (mostly non-typable): 15-30%
Moraxella catarrhalis: 3-20%
Viral (especially RSV, rhinovirus): 5-22%
No pathogen identified: 16-25%
Streptococcus pneumoniae
Gram positive, diplococcus
Resistance due to changes in the penicillin binding protein
Capsule- blocks phagocytosis by interfering with the
deposition of complement on surface of organism
Choline-binding proteins- bind carbohydrates present
on surface of epithelial cells
Neuraminidases- cleave sialic acid in host mucins
_Autolysin A (LytA)_- degrades peptidoglycan and causes α-hemolysis during growth
Pneumolysin- pore forming toxin is released disrupts cilia
- Transmitted by contact with secretions
- Asymptomatic colonization of naso oropharynx
- Can be a carrier for weeks to months especially in winter
- If spreads to middle ear or terminal airways leads to rapid inflammation
These illnesses are common, often occur together, and caused by similar agents…
Bacterial conjunctivitis, otitis media, and sinusitis
Recurrent otitis media is associated with…
conductive hearing loss as well as meningitis and mastoiditis
Acute otitis media is treated with ________ but patients need to be monitored for treatment failure as there is an increasing number of drug resistant strains and physicians need to minimize selection for these strains by practicing appropriate writing of prescriptions.
amoxicillin
beta-lactam; binds PBP to block transpeptidation step
Match the bacteria/virus with the description…
Red eye, mild cold, clear drainage
Adenovirus
Match the bacteria/virus with the description…
Visual field deficit most common in
HIV infected individuals
Cytomegalovirus
Match the bacteria/virus with the description…
Releases pneumolysin pore forming toxin
Streptococcus pneumoniae
Match the bacteria/virus with the description…
Green-yellow discharge from the eyes
Neisseria gonorrhea
Haemophilus influenzae
Small, pleomorphic, gram-negative, coccobacillus, nonmotile, biofilms, facultative anaerobe
- Humans are only known host
- Fastidious require additional blood factors for growth hematin (X) and NAD (V) both present in chocolate agar
- Nontypeable- nonencapsulated (NTHi) colonize nasopharynx in 80% of people and if spreads to the eustachian tubes causes otitis media. (vaccine available)
- Many express β-lactamases
- Other mucosal sites of infection include
genital tract and conjunctivitis
Moraxella catarrhalis
Gram-negative, aerobic, diplococcus, oxidase-positive, nonmotile, fastidious-chocolate agar, pili
- Colonization of upper respiratory track in infants
- 95% of M. catarrhalis produce β-lactamases
- Hockey puck test- easily slide across agar and be stacked
Recommended treatment for Acute Otitis Media
- 6-24 months start empiric treatment: Amoxicillin provides coverage against Streptococcus pneumoniae, Haemophilus influenzae with limited side effects (?).
- If no improvement within 48 hours switch to _Amoxicillin- Clavulanate _
For which organisms would you expect clavulanate to potentially expand coverage?
clavulanate is a beta-lactamase inhibitor
clavulanate is commonly used with beta-lactam drugs such as amoxicillin
In this case it would improve coverage for organisms that have resistance through beta-lactamases… such as
Moraxella catarrhalis
Haemophilus influenzae
Otitis externa- common etiologies
Acute localized ?
Acute diffuse ?
Malignant ?
Fungal ?
- Acute localized- most often Staphylococcus; pustule or furuncle associated with hair follicles
- Acute diffuse- Pseudomonas aeroginosa itches, red canal, and painful
- Malignant- Pseudomonas aeroginosa, invasion of adjacent bone and cartilage which can progress to cranial nerve palsy and death. More common in elderly, poorly controlled diabetes, and immunocompromised.
- Fungal- Aspergillus and Candida
Staphylococcus aureus
general info and virulance factors
clustered, Gram positive cocci
Virulence factors
- Capsule and Protein A binds Fc portion of IgG to interfere with phagocytosis
- Coagulase binds prothrombin initiating the polymerization of fibrin and clotting- retard migration of phagocytes to site of infection
- Membrane damaging toxins hemolysin and leukotoxin
