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bacterial Conjunctivitis
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bacterial Conjunctivitis
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infective Conjunctivitis
INFECTIVE CONJUNCTIVITIS
Infective conjunctivitis, i.e., inflammation of the conjunctiva caused by microorganisms is the commonest variety. This is in spite of the fact that the conjunctiva has been provided with natural protective mechanisms in the form of low temperature due to exposure to air, physical protection by lids, flushing action of tears, antibacterial activity_of lysozymes and humoral protection by the tear immunoglobulins.
BACTERIAL CONJUNCTIVITIS
There has occurred a relative decrease in the incidence of bacterial conjunctivitis in general and those caused by gonococcus and corynebacterium diphtheriae in particular. However, in developing countries it still continues to be the commonest type of conjunctivitis. It can occur as sporadic cases and as epidemics. Outbreaks of bacterial conjunctivitis epidemics are quite frequent during monsoon season.
Etiology
A. Predisposing factors for bacterial conjunctivitis, especially epidemic forms, are flies, poor hygienic conditions, hot dry climate, poor sanitation and dirty habits cause of bacterial conjunctivitis and blepharoconjunctivitis.
- Staphylococcus epidermidis is an innocuous flora of lid and conjunctiva. Rarely it can also produce blepharoconjunctivitis.
- Streptococcus pneumoniae (pneumococcus) produces acute conjunctivitis usually associated with petechial subconjunctival haemorrhages. The disease has a self-limiting course of 9-10 days.
- Streptococcus pyogenes (haemolyticus) is virulent and usually produces pseudomembranous conjunctivitis.
- Haemophilus influenzae (aegyptius, Koch-Weeks bacillus). It classically causes epidemics of mucopurulent conjunctivitis, known as ‘redeye’ especially in semitropical countries.
- Moraxella lacunate (Morax-Axenfeld bacillus) is most common cause of angular conjunctivitis and angular blepharo conjunctivitis.
- Pseudomonas pyocyanea is a virulent organsism. It readily invades the cornea.
- Neisseria meningitidis (meningococcus) may produce mucopurulent conjunctivitis.
- Corymebacterium diphtheriae causes acute membranous conjunctivitis. Such infections are rare now- a-days.
C. Mode of infection. Conjunctiva may get infected from three sources, viz, exogenous, local surrounding structures and endogenous, by following modes :
- 1. Exogenous infections may spread: (i) directly through close contact, as air-borne infections or as water-borne infections; (ii) through vector transmission (e.g. flies); or (iii) through material transfer such as infected fingers of doctors, nurses, common towels, handkerchiefs, and infected tonometers.
- 2. Local spread may occur from neighbouring structures such as infected lacrimal sac, lids, and nasopharynx. In addition to these, a change in the character of relatively innocuous organisms present in the conjunctival sac itself may cause infections.
- 3. Endogenous infections may occur very rarely through blood