Trachoma Flashcards
How was chlamydia classified earlier ?
It was classified in between bacteria and viruses , as a separate organism
How is chlamydia classified now ?
Now classified as bacterium belonging to the family chlamydiaceae
What are the two genera coming under the family chlamydiaceae ?
Chlamydia
Chlamydophilia
What is chlamydia ?
Small , obligate INTRACELLULAR , GRAM NEGATIVE BACTERIA
Has both DNA & RNA , ribosomes and cell wall similar to gram negative bacteria
How does it differ form true bacteria ?
It lacks the peptidoglycan layer
Why chlamydia is called as a energy parasite ?
This is because it lacks the ability to produce its own ATP , therefore it uses the host ATP
What are the two morphologically distinct forms of chlamydia ?
Elementary bodies
Reticulate bodies
What are EB ?
EB / elementary bodies - extracellular infectious particles that attaches to susceptible host cells , enters the cytoplasm of the host cells forms a vesicle and differentiates into RB
What is RB ?
RB - Reticulate body
Metabolically active form divides by binary fission inside the vesicle and develops into inclusion body ( vesicle having many EB ) which is peri nuclear in nature and releases EB by burst of inclusion body infecting new cells
Other name of trachoma
Egyptian ophthalmia
Define trachoma
Trachoma is a CHRONIC KERATOCONJUNCTIVITIS , primarily affecting the superficial epithelium of cornea and conjunctiva simultaneously ; characterised by mixed follicular and papillary response of conjunctival Tissue , pannus formation and cicatrization in late stages giving rough appearance
Causative Agent of trachoma ?
Chlamydia trachomatis biovar TRIC
What are HP bodies ?
Halberstaedter prowazek bodies - cytoplasmic inclusion bodies produced by chlamydia trachomatis biovar tric
How many serovars are present under chlamydia trachomatis biovar tric ?
12 serovars
A,B,Ba,C - hyperendemic trachoma
D to K - inclusion conjunctivitis
What is the source of infection of trachoma in endemic zones?
Discharge of the affected person
Clinical features of trachoma is described in how many stages ?
Two stages
Phase of active inflammatory trachoma - occurs in childhood due to active chlamydial infection
Phase of chronic cicatricial trachoma - occurs in middle age due to chronic mild grade inflammation
What determines the symptoms of active inflammatory / active trachoma ?
Presence (most common ) / absence of secondary bacterial infection
Features of pure trachoma ( no secondary bacterial infection )
M - mild foreign body sensation
O - occasional lacrimation
S - stickiness of the lids
S - scanty mucoid discharge
These symptoms are so mild that the disease is usually neglected and hence called TRACHOMA DUBIUM
Symptoms of trachoma in the presence of secondary bacterial infection ?
Similar to acute bacterial conjunctivitis / acute mucopurulent conjunctivitis
Discomfort , foreign body sensation , redness of sudden onset ( due to engorgement of vessels )
Blurring of vision due to presence of mucus flakes in front of cornea
Mild photophobia
Mucopurulent discharge
Stickiness of the lid early in the morning
Coloured halos that disappears on washing the discharge
What are the conjunctival signs of active inflammatory trachoma with secondary bacterial infection ?
Congestion
Follicles
Papillae
Structure of conjunctival follicles
Boiled sago grain appearance found in palpebral and bulbar conjunctiva (pathognomonic of trachoma)
Central part - mononuclear histiocytes , multinucleated cells called LEBER CELLS , few lymphocytes
Cortical part - zone of lymphocytes showing active proliferation
Peripheral part - blood vessels + signs of necrosis
Describe papillary hyperplasia
Gives red velvety appearance to the Tarsal conjunctiva
Has dilated blood vessels , lymphocytes covered with hypertrophied epithelium
What are the corneal signs in active inflammatory trachoma having secondary bacterial infection ?
Superficial keratitis
Corneal ulcer
Progressive pannus
Herbert follicles
