Otitis media, Otitis externa , and Eye diseases: 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.

-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. N

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.

-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.

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. N

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).

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.

Diagnosis: N -Necrotizing otitis externa is a form of infection in immunocompromised patients. -This type of infection could be complicated by inflammation of cranial nerves and their branches ; facial nerve paralysis. 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.

Sty is a painful red swelling on the margin of the eyelid. Treatment: 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.

3-Fungal keratitis: Keratomycosis: Etiology: Fusarium species. -Infection is established due to corneal injury in agriculture workers or immunocompromised patients. Fusarium Chlamydospores. Fusarium Macroconidia.

Etiology: Herpes simplex virus types 1 and 2. Diseases: 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.

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.

A-Bacterial 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.

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). N

Chlamydia trachomatis: 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).

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: 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. N

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.

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. N

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.