Otitis Media and Otitis Externa

Otitis media — pathogens by mechanism

• Bacterial ascent from the nasopharynx: S. pneumoniae, nontypeable H. influenzae, and M. catarrhalis reach the middle ear through a dysfunctional Eustachian tube. Since routine conjugate pneumococcal vaccination, nontypeable H. influenzae has become a relatively larger share of isolates.
• Viral prodrome: RSV, rhinovirus, influenza produce tubal mucosal edema; viruses alone can cause effusion without bacterial superinfection.
• Anatomic: in children the Eustachian tube is shorter, wider, and more horizontal, so reflux of nasopharyngeal secretions is easy and clearance is poor — the single best explanation for the age distribution.

Otitis externa — pathogens by mechanism

• Moisture + barrier loss: water washes out the acidic, lipid-rich cerumen film that inhibits growth; the alkaline, macerated canal favors Pseudomonas aeruginosa and S. aureus.
• Trauma: cotton swabs, hearing aids, earbuds, and instrumentation inoculate organisms into abraded skin.
• Flora shift: prolonged topical antibacterials or chronic drainage select for Aspergillus niger and Candida (otomycosis).

Modifiable risk factors

• Otitis media: tobacco smoke exposure, group daycare attendance, supine bottle-feeding, pacifier use beyond infancy, absent or short breastfeeding, uncontrolled allergic rhinitis, and missed pneumococcal/influenza vaccination (AAP and ACIP both cite vaccination as reducing AOM burden).
• Otitis externa: swimming and humid climates, cotton-swab use, occlusive devices, and retained water after bathing.

Non-modifiable risk factors

• Otitis media: age roughly 6–24 months (peak), male sex, craniofacial anomalies — cleft palate (tensor veli palatini dysfunction) and Down syndrome — adenoid hypertrophy, immunodeficiency, ciliary dyskinesia, family history, and higher incidence in American Indian/Alaska Native children.
• Otitis externa: narrow or exostotic canals, eczema/psoriasis, prior radiation, and diabetes mellitus or immunocompromise, which predispose to necrotizing (malignant) otitis externa rather than simple canal infection.

OTITIS MEDIA

• Eustachian tube dysfunction (ETD) is the primary pathogenic mechanism; impaired drainage and equalization of middle ear pressure leads to negative pressure and transudative fluid accumulation
• Bacterial/viral upper respiratory infection causes mucosal edema of the Eustachian tube orifice, worsening obstruction; common pathogens include Streptococcus pneumoniae, Haemophilus influenzae (nontypeable), and Moraxella catarrhalis
• Effusion progression: initially serous (serous otitis), progresses to purulent if bacteria proliferate; pus accumulation increases middle ear pressure, potentially causing tympanic membrane perforation
• Risk factors increase ETD: adenoid hypertrophy (most common in children), cleft palate, smoking exposure, allergic rhinitis, Down syndrome, and bottle-feeding in supine position
• Viral coinfection frequently precedes bacterial infection; respiratory syncytial virus (RSV), influenza, and rhinovirus are common precipitants

OTITIS EXTERNA

• Disruption of normal skin barrier in the external auditory canal—caused by trauma (cotton swabs, hearing aids), excessive moisture (swimming, high humidity), or cerumen impaction
• Bacterial overgrowth in warm, moist environment; Pseudomonas aeruginosa is most common (>90% of cases), followed by Staphylococcus aureus and fungi (Aspergillus, Candida)
• Inflammatory cascade: bacterial colonization triggers intense local inflammation with edema, erythema, and purulent drainage; the canal's rigid bony framework means swelling causes pain disproportionate to the infection severity
• Fungal otitis externa ("otomycosis") develops in chronically draining ears or with prolonged antibiotic use (alters normal flora); more common in warm, humid climates

OTITIS MEDIA

• Otalgia (ear pain) - often severe, night-time worse, may be referred pain; very young children present with inconsolability, fever, pulling at ears, or behavioral changes rather than complaint of ear pain
• Fever and systemic symptoms - often accompany acute otitis media; may include URI prodrome (cough, rhinorrhea, sore throat)
• Conductive hearing loss - transient, due to fluid-filled middle ear blocking ossicular chain transmission; parents often notice child asking "what?" frequently
• Otoscopic findings: hyperemia and bulging of tympanic membrane (most specific finding), opacification/haziness, loss of normal landmarks, fluid level or air-fluid interface (seen as horizontal line), spontaneous perforation with purulent discharge
• Asymptomatic middle ear effusion - discovered incidentally on exam; persists after acute infection resolves; can last weeks to months
• Important variant—Acute Mastoiditis: develops from inadequately treated otitis media; presents with postauricular swelling, erythema, tenderness, and ear protrusion ("battle sign"), plus fever and systemic toxicity

OTITIS EXTERNA

• Severe, disproportionate otalgia - often intense pain out of proportion to findings; tragal tenderness and pain with pinna manipulation are pathognomonic findings
• Purulent discharge from ear canal - may be foul-smelling, especially with Pseudomonas; debris and edema may obscure tympanic membrane visibility
• Ear canal edema and erythema - swollen canal appears pale/white from edema; severe cases cause canal to nearly close
• Conductive hearing loss - mild, transient, due to canal debris and edema (not fluid in middle ear)
• Otomycosis-specific findings: fungal hyphae or spores visible in canal, black/white/yellow debris, minimal purulence, often less severe pain than bacterial disease
• Systemic toxicity absent - unlike otitis media, patients are typically afebrile and non-toxic unless severely immunocompromised

OTITIS MEDIA

• Otoscopy (gold standard for acute otitis media): requires clear visualization of tympanic membrane; look for hyperemia, bulging, opacification, and loss of normal light reflex; performs best in calm, cooperative patient with good lighting and appropriate speculum size
• Tympanometry (impedance audiometry): non-invasive, objective measure of middle ear function; Type A = normal, Type B = flat (suggests effusion or perforation), Type C = negative pressure (suggests Eustachian tube dysfunction); particularly useful for diagnosing otitis media with effusion (OME) when otoscopy is limited
• Diagnostic criteria for acute otitis media (AOM) require: (1) recent, rapid onset of symptoms; (2) middle ear effusion (confirmed by otoscopy or tympanometry); and (3) signs of middle ear inflammation (bulging membrane, otalgia, fever, or otorrhea)
• CBC, blood cultures only if severe systemic illness or concern for complications (rarely routine); imaging (CT/MRI) reserved for suspected mastoiditis or other complications
• Culture (not routine): obtain if perforation with discharge, or recurrent/treatment-resistant disease; swab canal and middle ear drainage if accessible

OTITIS EXTERNA

• Clinical diagnosis based on otoscopy and history: ear pain + canal edema/erythema ± discharge; no special tests required in typical cases
• Otoscopy findings: canal edema (pale, white appearance), erythema, possible purulent or debris-filled canal; tympanic membrane should be visible and normal (if not, reconsider diagnosis toward otitis media or cholesteatoma)
• Culture and susceptibility indicated only if: immunocompromised host, failure to improve after 2 weeks of therapy, or recurrent infections; Pseudomonas resistance patterns (fluoroquinolone resistance) vary geographically
• Imaging (CT) reserved for malignant otitis externa (see complications): shows mastoid and temporal bone involvement; performed if clinical concern for osteomyelitis

OTITIS MEDIA

Acute Otitis Media - Observation vs. Antibiotics

• Observation without antibiotics is now acceptable in selected cases per current guidelines: age ≥2 years, mild disease, reliable follow-up, and no severe systemic illness; approximately 80% of cases self-resolve within 3 days
• First-line antibiotic: Amoxicillin 45 mg/kg/day (max 1000 mg/day) divided BID-TID × 10 days—covers S. pneumoniae and H. influenzae; preferred empiric choice due to excellent middle ear penetration and safety profile
• Amoxicillin-clavulanate (Augmentin) for suspected resistant organisms or initial treatment failure; high-dose formulation (90 mg/kg/day amoxicillin component) preferred over standard-dose
• Alternative for penicillin-allergy: 2nd or 3rd generation cephalosporin (cephalexin, cefdinir, cefpodoxime) if non-severe allergy; use macrolide (azithromycin) only if true IgE-mediated penicillin allergy (less effective); fluoroquinolone (ciprofloxacin) if tube present
• Duration: standard 10-day course; 5-day course emerging as alternative for selected low-risk children, but not yet standard
• Adjunctive care: analgesics (ibuprofen, acetaminophen), topical anesthetics (benzocaine otic drops) for pain; avoid ototoxic drops if perforation present
• Recurrent/resistant otitis media (≥3 episodes in 6 months or

Intratemporal (extracranial) complications of otitis media

• Tympanic membrane perforation: pressure necrosis from purulent effusion; signaled by sudden pain relief with otorrhea. Most heal spontaneously; persistent perforation with chronic drainage defines chronic suppurative otitis media.
• Acute mastoiditis: spread through the aditus ad antrum with coalescence of air-cell septa. Postauricular erythema, fluctuance, and an anteriorly/inferiorly displaced auricle. Emergency — IV antibiotics, contrast CT of the temporal bone, and urgent otolaryngology consultation for possible mastoidectomy.
• Cholesteatoma: retraction pocket or perforation traps keratinizing squamous epithelium, which erodes ossicles. Painless, foul otorrhea with a pearly white mass; surgical, not medical, disease.
• Facial nerve palsy: CN VII traverses the middle ear and may be dehiscent — ipsilateral peripheral palsy mandates urgent drainage/myringotomy.
• Labyrinthitis: vertigo and sensorineural hearing loss from inner-ear spread.
• Conductive hearing loss with speech/language delay: the reason AAO-HNS recommends audiometry for effusion persisting about three months.

Intracranial complications — all emergencies

• Meningitis (most common), epidural/subdural empyema, temporal lobe or cerebellar abscess, and sigmoid/lateral sinus thrombosis (spiking "picket-fence" fevers, headache). Gradenigo syndrome from petrous apicitis: otorrhea, deep retro-orbital pain (CN V), and CN VI palsy with diplopia. Obtain contrast-enhanced CT/MRI with venography and start IV antibiotics.

Complications of the disease process in otitis externa

• Necrotizing (malignant) otitis externa: Pseudomonas skull-base osteomyelitis in elderly diabetics or immunocompromised patients. Granulation tissue at the bony–cartilaginous junction, deep pain, cranial neuropathies, markedly elevated ESR. Emergency — imaging plus prolonged systemic antipseudomonal therapy (e.g., ciprofloxacin), not drops alone.
• Canal stenosis and periauricular cellulitis from untreated edema.

Treatment-related complications

• Aminoglycoside- or alcohol-containing otic drops with a perforated membrane or patent tube: ototoxicity/sensorineural loss — use fluoroquinolone drops instead.
• Neomycin contact dermatitis; amoxicillin-associated rash (florid with EBV), diarrhea with clavulanate, and C. difficile colitis.
• Tympanostomy tubes: otorrhea, granulation, persistent perforation, tympanosclerosis.

• Pain on tragal pressure or pinna traction = otitis externa; pain without it, plus a bulging drum = otitis media. This one maneuver separates the two stems.
• The most specific otoscopic sign of AOM is a bulging tympanic membrane with impaired mobility on pneumatic otoscopy, which the AAP guideline treats as the diagnostic anchor. The classic distractor is erythema alone — a crying, febrile child can have a red drum with no effusion, and that is not AOM.
• Conjunctivitis plus otitis in a toddler is the otitis–conjunctivitis syndrome of nontypeable H. influenzae, a beta-lactamase producer — the expected answer is amoxicillin-clavulanate rather than plain amoxicillin.
• Otitis media with effusion is not treated with antibiotics, antihistamines, decongestants, or steroids. AAO-HNS recommends watchful waiting with hearing assessment; tympanostomy tubes are for persistent bilateral effusion with documented hearing loss or recurrent AOM.
• Unilateral serous effusion in an adult — especially an adult of Southeast Asian descent or with a neck mass or epistaxis — should prompt nasopharyngoscopy for nasopharyngeal carcinoma obstructing the Eustachian tube. This is the association examiners test most reliably.
• Elderly diabetic with severe otalgia and granulation tissue at the bony–cartilaginous junction: the single best next step is imaging of the temporal bone and systemic antipseudomonal therapy for necrotizing otitis externa — topical drops alone are the trap answer.
• Never choose aminoglycoside otic drops when the drum is perforated or a tube is in place (ototoxicity); a fluoroquinolone otic preparation is the safe choice.
• Postauricular swelling with the auricle pushed forward means mastoiditis: admit, IV antibiotics, CT, ENT consult. Discharge on oral amoxicillin is the wrong answer.
• Painless foul otorrhea with a white keratin mass or marginal retraction pocket is cholesteatoma — surgical referral, not another antibiotic course.