Otitis Media Flashcards
Otitis externa?
External otic canal infection
Otitis media?
Middle ear canal infection
Labrinthitis?
Inner ear infection - more rare, but causes more damage
Mastoiditis?
Mastoid bone infection - also more rare, but causes more damage
What is acute otitis media?
Bacterial or Viral cause
Pain, red ear drum, pus and fever
What is otitis media with effusion?
Build up of fluid in Eustachian tube.
- No infection, associated with URI (upper respiratory infection), cigarette smoke, allergies
- Resolves on its own
What is the pathognesis of Acute otitis media (AOM)?
- URI or allergic conditions may cause congestion of mucosa
- Narrowing and obstruction Eustachian tubes prevents ventilation and drainage. Anatomic abnormalities or enlarged adenoids increases likelihood of blockage.
- Accumulation of secretions of middle ear and if pathogen is present AOM
How do you open you Eustachian tubes?
Close mouth and nose and blow.
-Can also open using gum
What is the epidemiology of acute otitis media?
- About 70% of children experience at least 1 episode of otitis media during childhood probably b/c tubes are more narrow and horizontal and immune system is not at well developed
- Less common in school age children, adolescence and adults
- More common: males & Native American/Alaskan Natives
What are the common etiologic agents of acute otitis media?
Strep, pneumoniae - 35-50%
H. influenzae (mostly non-typable) - 15-30%
Moraxella catarrhalis - 3-20%
Viral (especially RSV, rhinovirus) - 5-22%
No pathogen identified - 16-25%
What are traits of Streptococcus pneumoniae?
Gram +, diplococcus
How does Strep pneumoniae spread?
- Secretion contact
- Asymptomatic colonization of nasa-oropharynx and can be a carrier for weeks to months (esp. WINTER)
- If spreads to middle ear or terminal airways it leads to RAPID INFLAMMATION
What makes people more susceptible to Strept, pneumoniae?
Chronic diseases, including alcoholism, diabetes mellitus, and chronic renal disease, interfere with normal defense can increase susceptibility.
How many serotypes are there of Strept. pneumoniae?
At least 91 bc they have unique surface capsules.
What are the virulence factors of Streptococcus pneumoniae?
- Resistance
- Capsule
- Choline-binding proteins
- Neuraminidases
- Pneumolysin
What Resistance does S. pneumoniae have?
Resistance due to changes in the penicillin binding protein.
What Capsule does S. pneumoniae have?
It’s capsule blocks phagocytosis by interfering with the deposition of complement on surface of organsim
What Choline-binding proteins does S. pneumoniae have?
The choline-binding proteins bind carbohydrates present on surface of epithelial cells.
What Neuraminidases does S. pneumoniae have?
They cleave host mucins
What pneumolysin does S. pneumoniae have?
It is a pore forming toxin that is released disrupts cilia.
What iron acquisition does S. pneumoniae have?
Iron acquisition A (PiaA) and uptake A (PiuA)
-This helps bc bacteria needs iron
What are the traits of Haemophilus influenzae?
Small, pleomorphic, gram -, coccobacillus, nonmotile, biofilms, facultative anaerobe
-Expresses Beta-lactamases
What do Haemophilus influenzae infect?
Humans are only known host
- Nontypeable- nonencapsulated (NTHi) colonize nasopharynx in 80% of people and if spreads to eustachian tubes causes otitis media
- Other mucosal sites of infection include genital tract and conjunctivitis
How to grow H. influenzae?
Fastidious requires additional blood factors for growth: hematin (X) and NAD (V) both present in chocolate agar
Does current Hib vaccine offer protection against NTHi?
NO - vaccine is specific to capsulated form
-Lately there has been inc. in cases cause by non-typable H flu and by pneumococcal strains not covered by vaccine
What are the traits of Moraxella catarrhalis?
Gram negative, aerobic, diplococcus, oxidase +, nonmotile, fastidious-chocolate agar, pili
What does Moraxella catarrhalis usually colonize?
Upper resp. tract of infants.
What is unique about Moraxella catarrhalis?
- 95% of M. catarrhalis produces Beta-lactamases
- Hockey puck test - easily slide across agar - not well attached to agar as other strains
How do you diagnose Otitis Media?
- Pneumatic otoscopy to asses TM
- Tympanometry - detect fluid in middle ear
- If not responding to therapy, collect aspirate for gram stain & culture bc recurrent infections can lead to hearing loss
How can you prevent Acute Otitis Media?
- Avoid cigarette smoke and sick children
- Brestfeed children & avoid bottles before bed (bottles build up pressure in ears)
- Wash hands often
- Stay up to date on vaccines - influenza and 13-valent pneumococcal conjugate vaccine
How should you treat Acute Otitis Media in 6-24 month year old?
Oral amoxicillin provides coverage against Streptococcus pneumoniae, Haemophilus influenzae with limited side effects.
What if baby’s ear infection doesn’t improve in 48 hours after amoxicillin?
Switch to amoxicillin - Clavulanate [since the bacteria may be resistant and have a beta-lactamase]
What if baby has a penicillin allergy?
Treat ear infection with azithromycin.
How should you treat an older kid/adult with acute otitis media?
- Pain management (acetaminophen and ibuprofen) and decongestants
- If multiple infections, prophylaxis may be considered
- Resistance is associated with previous infection and may be related to compliance - try to reduce doses per day and have shorter treatment course
What amount of antibiotic prescriptions does acute otitis media account for in the US?
30%
What organisms would you expect clavulanate to potentially expand coverage?
Moraxella catarrhalis & Haemophilus influenzae
What is used to treat recurrent ear infections?
Ear tubes - TM is cut, tube inserted and fluid is drained
-Tubes fall out and incision heals on own
What can cause conductive hearing loss and/or delayed speech?
Perforation of the TM and erosion of ossicles
Where can infection spread in otitis media?
Mastoid, Inner ear, Temporal bone, Meninges & Brain
What is a cholesteatoma? What happens to the TM?
- Cyst of epithelial cells
- It is sucked inwards
What does an ear infection that has spread to the mastoid bone look like?
There is a red, swollen area behind the ear and the outer ear is turned forward.
What is otitis externa?
Swimmer’s ear - unilateral inflammation of ear canal, pain, itching and purulent ear drainage.
What is Cerumen and why is it helpful?
Earwax. It contains lysozyme and is slightly acidic deterring microbial growth.
What are risk factors for Otitis externa?
Maceration - trauma, foreign bodies, excessive moisture (dry ears after swimming), extension of middle ear infection, diabetes
What are four main types of otitis externa (etiologies)?
- Acute localized
- Acute diffuse
- Malignant
- Fungal
What causes Fungal Otitis externa?
Aspergillus and candida albicans
What causes malignant otitis externa?
Pseudomonas aeruginosa
-Invasion of adjacent bone & cartilage which can progess to cranial nerve palsy and death.
More common: elderly, poorly controlled diabetes, immunocompromised
What causes acute diffuse otitis externa?
Pseudomonas aeruginosa
-Itches, red canal and painful
What causes acute localized otitis externa?
Most often Staphylococcus pustule or furuncle associated with hair follicles
How do you diagnose otitis externa?
It can be complicated due to contamination from surface bacteria.
How do you treat cellulitis or fungal otitis externa?
You could use a topical antibiotic:
Neomycin + polymyxin + hydrocortisone
How to treat/manage otitis externa?
- Avoid flushing unless TM is intact
- Cleans with topical solutions often of low pH (acetic acid) to deter bacterial and yeast growth
- Treat with analgesics (NSAIDs, acetaminophen)
What causes red eye, mild cold and clear drainage?
Adenovirus
What causes visual field deficit and is most common in HIV infected individuals?
Cytomegalovirus
What releases pneumolysin pore forming toxin?
Streptococcus pneumoniae
What causes green-yellow discharge from the eyes?
Neisseria gonorrhea (but it doesn’t infect ears)
What can recurrent otitis media cause?
Conductive hearing loss, meningitis and mastoiditis
Why do patients need to be monitored after given amoxicillin for otitis media treatment?
Treatment failure could occur due to drug resistant strains of bacteria.
What are the links between bacterial conjunctivitis, otitis media and sinusitis?
They are common, often occur together and are caused by similar agents.
