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EAR INFECTIONS
These include;
Otitis externa, otitis
media,mastoiditis
Otitis externa
• Pain and itching that results may be
severe because of the limited space for
expansion of the inflamed tissues.
• Otitis externa can be subdivided into 4;
• 1.Acute localised otitis externa,2.Acute
diffuse otitis externa 3.Chronic otitis
externa and 4.Malignant otitis externa.
Otitis externa
• Infection of the external auditory
canal(otitis externa) is similar to infection
of skin and soft tissue elsewhere.
• Unique problems occur because the canal
is narrow and tortuous,fluid and foreign
objects enter, are trapped and cause
maceration and irritation of superficial
tissues.
Structure –Ear canal
• The external auditory canal is about 2.5cm
long from the conchae of the auricle to the
tympanic membrane.
• The outer half of the canal is
cartilaginous,the medial half tunnels
through the temporal bone.
• A constriction, the isthmus is present at
the juntion of the osseus and cartilaginous
parts.
Structure- ear canal
• The skin of the canal is thicker in the
cartilaginous portion and includes a well
developed dermis and subcutaneous
layer.
• The skin lining the osseus portion is
thinner and and lacks a subcutaneous
layer.
• Hair follicles are numerous in the outer
third and fewer in the inner 2/3 of the canal
Aetiological agents
• The microbial flora of the external Canal is
similar to the flora of the skin elsewhere.
• There is predominance of staph. Epidermidis , S.
aureus and corynebacteria and lesser extent
anaerobic bacteria like propionibacterium acnes
• Others streptococcus pneumoniae,Haemophilus
influenza,moraxella catarhalis
• Gm neg bacilli- Pseudomonas aeruginosa
Pathogenesis
• The ear canal epithelium absorbs moisture
from the environment.
• Desquamation of the superficial layers of
the epithelium may follow;In this warm
moist environment,the organisms in the
canal may flourish and ivade the
macerated skin.
• Inflammation and suppuration folllow.
Clinical Manifestations
• Acute localised otitis externa may occur as
a pustule or furuncle associated with hair
follicles.-Staph aureus.
• Erysipelas caused by group A
sreptococcus- may cause hemorrhagic
bullae on the canal and tympanic
membrane.
• Adenopathy in the lymphatic drainage
areas is often present.
• Treatment
• Depends on presentation;
• Systemic antibiotics/ Incision and
drainage.
Clinical Manifestations
• Acute diffuse otitis externa(swimmers ear)
occurs mainly in hot and humid weather.
• Ear is itchy, painful and canal is edematous and
red.
• Gm neg bacilli esp P aeruginosa.
• Treatment-topical eg neomycin/polymyxin in
steroid/systemic antibiotics
• Chronic otitis externa- due to irritation of
drainage from the middle ear in patients with
chronic suppurative otitid media.
Clinical manifestations
• Itching may be severe.Management is by
treating the otitis media also.
• Organisms raremycobacteria,treponemes, yaws,leprosy.
• Invasive malignant otitis externa is a
severe necrotizing infection that spreads
from the squamous epithelium of the ear
canal to adjacent areas of soft tissue,blood
vessels , cartilage and bone.
• This invasive otitis externa is associated with
pain and tenderness of the tissues around the
ear and mastoid accompanied by pus drainage
from the canal.
• At risk include
diabetics,immunocompromised,debilitated and
elderly patients.
• Complications- life threatening disease may
result by spread of infection to the meninges and
brain.
Malignant otitis externa cont
• Cranial nerves 7, 9,10,12 may be
paralysed.
• Cause – P aeruginosa.
• Treatment-Clean the canal devitalised
tissues removed,ear drops with
antipseudomonal and steroid activity given
and systemic therapy for 4-6
weeks.ticarcillin/piperacillin/a ceftazidime
with aminoglycoside
Otitis Media
• Defined by presence of fluid in the middle
ear accompanied by signs and symptoms
of the illness.
• Peak incidence occurs in the first 3 yrs of
life.
• The disease is less common in the school
aged child,adolescent and adult.
Associated factors
• Otitis media has been associated with;
• Immunosuppression,passive smoking,poor
breastfeeding,introduction of infants into
large day care groups,
• Race and ethnicity-canadian eskimos and
australian aborigines have extraordinary
incidence and severeity of otitis media.
Associated factors
• Age at the time of first episode of acute
otitis media is a powerful predictor of
recurrent middle ear infections.
• Males >females
• Some children have anatomical changescleft palate,cleft uvula,submucous cleft –
or alteration of the normal physiologic
defenses-patulous eustachian tube.
Pathogenesis
• The middle ear is lined by respiratory epithelium
with ciliated cells mucus secreting goblet cells
and cells capable of secreting local
immunoglobulins.
• Anatomic or physiological dysfuntion of the
Eustachian tube appears to play a critical role in
the development of otitis media.
• The eustachian tube has at least 3 physiologic
functions with respect to the middle ear;
pathogenesis
• These are 1. protection of the ear from
nasopharyngeal secretions,2. drainage
into the nasopharynx of secretions
produced from the middle ear,
3.Ventilation of the middle ear to
equilibrate pressures to be as the
atmospheric –external ear canal pressure.
pathogenesis
• When one or more of these funtions is
compromised,accumulation of fluid in the middle
ear and subsequent infections may occur.
• (congestion of the mucosa of the eustachian
tube can result in obstruction;secretions that are
constantly formed by the mucosa of the middle
ear accumulate behind the obstruction, and If a
bacterial agent is present, a suppurative otitis
media may result.)
Bacterial agents –otitis media
• Streptococcus pneumonia,Haemophilus
infleunza,Staphylococcus aureus,Group A
streptococcus,Moraxella catarhalis.
• Others chlamydia
trachomatis,mycoplasma
pneumonie,diphtheritic otitis,mycobacterial
tb and chelonae
Clinical course
• Acute otitis media is defined by the presence of
fluid in the middle ear along with
signs/symptoms of acute illlness.
• Signs and symptoms may be specific eg ear
pains, ear discharge,hearing loss; or non
specific eg fever, irritability,lethargy.
• Vertigo, nystagmus,tinnitus can also occur
• Fluid can persist in the middle ear for prolonged
periods after onset of acute otitis media even
though symptoms may resolve within a few days
of intiation of antimicrobial treatment
Clinical course
• The common causes of otitis media are
recovered frequently in cultures.
• However if the patient is toxic or has focal
infection elsewhere,culture of the blood and the
focus are warranted.
• Needle aspirations of the middle ear fluid
(tympanocentesis) can be done in critically ill
patients,the patient who has not responded to
the initial antimicrobial therapy in 48-72 hrs and
is toxic, and patient with altered host defences
eg immunological defect including the newborns.
treatment
• Amoxicillinclavulanate,cefuroxime,cefixime,erythromy
cin.
• ?Role of oral and nasal decogestants
given alone or in combination with
antihistamine-may relieve obstruction of
the eustachian tube.
Chronic otitis media
• This term includes recurrent episodes of
acute infection and prolonged duration of
middle ear effusions usually resulting from
a precious episode of acute infection.
• Recurrent episodes of acute infection can
be managed by chemoprophylaxis (eg
amoxicillin given in winter and spring) and
immunoprophylaxis = pneumococcal
vaccination
Chronic otitis media
• Middle ear effusions can be managed
surgically
• This can be by Myringotomy- incision of
the tympanic membrane,adenoidectomy,
and insertion of tympanostomy tubes
Mastoiditis
• The proximity of the mastoid to the middle
ear cleft suggests that most cases
suppurative otitis media are associated
with inflammation of the mastoid air cells.
• Hyperaemia,edema,serous then purulent
exudate collects in the cells
• Bone necrosis due to pressure of the
exudate.
Clinical manifestations
• Acute mastoiditis is usually accompanied
by acute infection in the middle ear.
• Specific features of mastoiditis include
swelling, redness and tenderness over the
mastoid bone;pinna is displaced outward
and downward and a purulent discharge
may be seen after perforation of the
tympanum.
Clinical manifestations
• Chronic otitis media with mastoiditis can
erode through the roof of the antrum
causing temporal lobe abscess or extend
posteriorly causing septic thrombosis of
the lateral sinus.
diagnosis
• Specimen- pus discharge from ear, freshly
from the tympanic membrane
• If the tympanic membrane is not
perforated,tympanocentesis should be
performed to obtain specimen from middle
ear.
• Cultures for bacteria
treatment
• Antibiotics are similar as those used in
otitis media• If the disease in the mastoid has had a
prolonged course,cover for staph aureus
and Gm neg enteric bacilli for initial
therapy until culture results ready.
• Mastoidectomy- when mastoid abscess
forms and sepsis has been controlled by
antibiotics.
Summary of pus examination
• DAY1;
• 1. description of specimen
macroscopically- colour,blood stain
• 2.culture on BA/Mac/Neomycin blood agar
if anaerobic infection suspected/LJ media
for recurrent or chronic otitis media/SDA
• 3.Gram smear –pus cells and bacteria
• ZN smear/KOH preparation/Darkfield mic
Pus exam
• DAY 2 onwards;
• Examine and report cultures