Otitis media, Otitis externa, and Eye diseases: Otitis media: is the inflammation of the area...
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Transcript of Otitis media, Otitis externa, and Eye diseases: Otitis media: is the inflammation of the area...
Otitis media, Otitis externa , and Eye diseases:
Otitis media:
is the inflammation of the area between Eardrum
(Tympanic membrane) and the inner ear; including
Eustachian tube.-Infections of air-filled cavities of the head occur when normal drainage routes become obstructed.-Infection of air-filled cavities of the head results in: 1-Otitis media. 2-Sinusitis. 3-Mastoiditis.
N
-Because the cavity of the middle ear is contiguous with the
mastoid air cells(spaces of temporal bone); individuals
with
acute otitis media also have mastoiditis.
N
-The majority of cases occur in children between 6 and 36 months of age.-Children are susceptible to otitis media for several reasons: 1-The medial orifice of the eustachian tube is more open in infancy than later in life.2-Milk feeding (giving a bottle at bedtime) results in reflux of pharyngeal contents into the lumen of eustachian tube.
3-Eustachian tube is shorter and more horizontal in young children. 4-The viral infection of upper respiratory tract and lymphoid tissue results in eustachian tube obstruction.
Pathogenesis:
-Inflammation of upper respiratory tracts due to: 1-Viral infections; influenza A or B, and adenovirus. 2-Allergy (Rhinitis).-Swelling of lymphoid tissue (Eustachian tonsil)around eustachian tube.-Eustachian tube obstruction.-Absorption of air of middle ear slowly by surrounding tissues.-Creation of negative pressure (vacuum) in the middle ear.
-Accumulation of fluids ; so normal flora of upper respiratory tract could invade middle ear space.
N
-Colonization of middle ear cavity lining epithelium.-If the microbe has a polysaccharide capsule: -Polyclonal lymphocyte activator; cytokines production; chemotaxis of immune cells and inflammation.
-Conductive hearing loss.
-If the infection is not treated; otitis media and mastoiditis could be complicated by: 1-Facial nerve paralysis. 2-Infection of peripheral nerves; results in deeper brain abscess.
N
3-Infection of veins that bridge surrounding bony structures and the cerebral cortex; septic thrombophlebitis) results in subdural empyema (in some cases; related to epidural abscesses).
Acute abscess is frequently caused by a mixed bacterial flora
consisting of obligate and facultative anaerobic bacteria;
similar to the mixture of microbes infecting middle ear,
mastoid, and sinuses.
N
Treatment of poly-microbial brain abscesses:Antibiotic combination:1-Vancomycin or Ceftriaxone: to cover Staphylococci and other Gram positive beta-lactamase producers.
2-Metronidazole: to cover anaerobic bacteria.
3-Quinolones or Macrolides working effectively at acidic pH.
The Normal flora of upper respiratory tracts:
-Streptococcus pneumoniae (Nasopharynx).
-Haemophilus influenzae (non-type b) (Nasopharynx).
-Moraxella catarrhalis (Nasopharynx).
-Staphylococcus aureus.
-Coagulase negative Staphylococcus species.
-Diphtheroids species.
-Neisseriae species.
-Candida species.
Causes of Otitis media:
1-Streptococcus pneumoniae (the most common cause).2-Non-typeable Haemophilus influenzae. (the second common cause).-Both Strep. pneumoniae and H. influenzae causes 80% of otitis media cases.
3-Moraxella catarrhalis. -Gram’s negative non-motile coccobacilli in pairs. -Aerobic fastidious oxidase positive bacteria.
4-Other normal flora of upper respiratory tracts(rare).
Clinical Classification of Otitis media:
1-Acute suppurative:- Pus accumulated in middle ear; mainly in infant
and children.2-Chronic:
A-Recurrent OM due to other causes. B-Secretory OM : Very common persisting middle ear
effusion after OM in 40% of cases.( Thick fluid consistency .)
Management: 1-Amoxicillin or Ceftriaxone.
2-Amoxicillin/Clavulanate for Beta-Lactamases strains .
Otitis Externa :
Otitis Externa: is an inflammation of the outer ear and ear canal.
-It is mainly caused by bacterial or fungal agents.
-Otitis externa could be established due to:
1-Swimming in polluted water (germs contamination).
2-Impairment in the integrity of the skin (dermatitis).
-Hospital acquired otitis externa could be caused by
hospital dwelling bacteria as a post-surgical infection.
Causes of Otitis Externa:Exogenous:-Pseudomonas aeruginosa (the most common cause).
Endogenous: Normal flora of outer ear canal: -Coagulase negative Staphylococci. -Staphylococcus aureus. -Gram negative bacilli. -Fungi: Candida species. Malassezia furfur.
Clinical classification of Otitis Externa:
1-Acute localized secondary to folliculitis: -Painful pustule with local lymph node enlargement; Staphylococcus aureus.
2-Acute diffuse (Swimmer’s ear): -Pseudomonas aeruginosa. -Itchy, painful, edematous, reddened OE with purulent discharge.
3-Chronic OE secondary to chronic otitis media. -Fungi, Candida plus other chronic disease (Immunocompromised Pat. ).
N
4-Malignant OE (Necrotizing OE) Secondary to diabetic microangiopathy; Pseudomonas spp. -Serious infection. -Not-malignant (Non-Cancerous). -Malignant in its progressive, fatal course. -Spreading of infection to surrounding bone, blood vessels, facial nerve and meninges.
-Complicated by inflammation of cranial nerves and their
branches ; facial (7th) nerve paralysis.
-It is associated with immunocompromised patients. -Diagnosis: Full investigations: CT Scan, MRI.
N
Management:1-Acute: As OM.2-Acute diffuse: Local Neomycin, Polymyxin.3-Chronic: Local imidazole for fungi and treatment of OM.4-Malignant OE: I.V Tobramycin and Ceftazidime (weeks) With surgery.
Diagnosis:Clinical specimen: Ear Swab (cotton swab).
N
Culture: on Enriched media. -Blood agar incubated under aerobic conditions. -Chocolate agar: incubated under anaerobic conditions.
Isolation of Pseudomonas species:-Encapsulated, motile, Gram negative bacilli.-Oxidase positive , Exopigments production.-Antibiotic resistance strains. (greenish yellowish exopigment production; pyoverdin).
N
Isolation of Staphylococci:Staphylococcus aureus:Gram positive cocci, coagulase positive, novobiocin sensitive, and Mannitol fermenters.Other Staphylococci:Gram positive cocci, coagulase negative, novobiocin resistance.
Novobiocin sensitivity Mannitol fermentation.
Infectious diseases of the Eye:
Keratitis: inflammation of transparent eye’s cornea; the anterior part of the eye (covers the iris, and pupil).Causes:1-Amoebic keratitis: a serious corneal infection usually affecting contact lens wearers. Etiology: Acanthamoeba.2-Bacterial keratitis: Due to injury of wearing contact lenses. Etiology: Staphylococcus aureus, &Pseudomonas species.
N
Staphylococcus aureus is a major cause of infections of
the eyelid and cornea.
Staphylococcus aureus can infect the glands of the eyelid;
resulting in the production of a sty.
Sty is a painful red swelling
on the margin of the eyelid.
Treatment:
bacitracin ointment.
N
3-Fungal keratitis: Keratomycosis: Etiology: Fusarium species. -Infection is established due to corneal injury in agriculture workers or immunocompromised patients.
Fusarium Chlamydospores. Fusarium Macroconidia.
N
4-Viral Keratitis: Etiology: Herpes simplex virus types 1 and 2. Diseases: A-Primary infectious keratitis: Vesicular eruption of the eyelid, infection of cornea leading to corneal ulcers.
B-Recurrent herpes keratitis: -(More common than primary keratitis). -In immunocompromised patients. -Mild irritation and photophobia.
N
5-Onchocercal Keratitis: Onchocerciasis: -Parasitic infection of the eye’s cornea (Corneal lesions). -Etiology: Onchocerca volvulus. -Transmitted by the bite of blackfly. -Disease: African River blindness.
n
Chemotherapy for Keratitis and Corneal Ulcers:1-Bacterial Keratitis: Local broad-spectrum antibiotics; Vancomycin and tobramycin.
2-Viral keratitis: Acyclovir.
3-Fungal Keratitis: Amphotericin B.
4-Amoebic keratitis: Propamidine drops plus oral ketoconazole.
Conjunctivitis:
Conjunctiva: is a thin, translucent, mucous membrane that lines the eyelid and covers the white portion of the eyeball.
Conjunctivitis is divided according to etiology into:A-Bacterial conjunctivitis: -Redness, swelling of the eyelid, and muco-purulent discharge. - Yellowish-greyish discharge: pyogenic cocci infection. -Treatment: Local bacitracin or neomycin.
N
Types of bacterial conjunctivitis:1-Trachoma: Etiology: Chlamydia trachomatis:
Serotypes A, B, Ba, and C causes chronic
keratoconjunctivitis (Trachoma) that results in blindness.
Trachoma is a leading cause of blindness in endemic areas
of northern India, the Middle East, and North Africa. Transmission: -Personal contact ; eye-to-eye via droplets by contaminated hands (transfer of elementary bodies). Chemotherapy: Oral azithromycin or tetracycline.
N
Chlamydia trachomatis:-Unicellular obligatory intracellular bacteria that has rigid cell wall.
-Infective stage: The elementary body.
-Inclusion bodies (Trachoma) infected conjunctival epithelial cells (Reticulate body: diagnostic stage).
N
2-Ophthalmia neonatorum : Etiology:
1-Neisseria gonorrhoeae:- The most severe cause of
hyperacute bacterial conjunctivitis of newborn.
-It is acquired during passage of newborn through the birth canal of a mother infected by gonococci.
-Neisseria species are Gram negative oxidase positive
diplococci that ferment glucose only .
N
2-Chlamydia trachomatis:(Ophthalmia neonatorum): -This type of newborn conjunctivitis is associated with serotypes D-K. - 50% of Infants born with infection due to passage through the birth canal. - inclusion conjunctivitis heals without eye damage
-Treatment of both types 1 and 2: (Prophylactic drug):
Erythromycin ointment; most strains of Neisseria
gonorrhoeae are Beta-Lactam resistant.
N
B-Viral Conjunctivitis:(Pink Eye): diffuse pinkness of Conjunctiva.
- Adenovirus infection is the most common cause of viral conjunctivitis.
- Acute conjunctivitis, and pharyngoconjunctival fever.- A more serious infection is epidemic keratoconjunctivitis,
which involves formation of a painful ulcer of the corneal epithelium.
Electron microscopy:
Double-Stranded DNA, Icosahedral
naked virus.
N
-Herpes simplex virus cause serious Herpetic keratoconjunctivitis, which requires treatment with
acyclovir .-Acute hemorrhagic conjunctivitis is a highly
contagious disease caused by: 1-Enterovirus 70 .
2-Coxsackievirus A24 .
Viral hemorrhagic Conjunctivitis
due to Enterovirus-70
infection.
Diagnosis of Eye infection:Clinical specimens:
1-Eye cotton Swab.2-Conjunctival Scraping .
1-Direct microscopy: A-Swab for Microbiology (Gram’s stain ):
detection of G+ve and G-ve bacteria, and yeast . B-Conjunctival scrapes for cytology lab: detection of Chlamydia diagnostic stage.
C-Conjunctival Scrapes for immunohistochemistry : detection of viral infections or Chlamydia infection .
N
2-Detection of viral genetic material and Chlamydia genetic material by molecular methods:
1-Nucleic acid DNA hybridization.(Probe hybridization).
2-PCR : Primer amplification of genetic material .
3-Cultivation of bacterial agents:- Eye swab should be inoculated on Enriched media.
- Blood agar and Chocolate agar should be incubated under aerobic and anaerobic conditions respectively.
Clinical significance: isolation of pyogenic cocci and Neisseria gonorrhoeae .
Detection of Virus and Chlamydia genetic materials by Immunofluorescent Microscopy:
Detection of viral antigen by Localization of specific Adenovirus- monoclonal antibodies. Coxsackievirus receptor on
Epithelial cells of conjunctiva .