• Infective conjunctivitis is inflammation of the conjunctiva due to infection.
• Infective conjunctivitis may be caused by bacteria, viruses, or chlamydia.
• Bacterial conjunctivitis is most commonly caused by Staphylococcus species, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
• Viral conjunctivitis is most commonly caused by adenovirus that may occur in isolation or as an epidemic. The most common strains cause a mild conjunctivitis associated with pharyngitis and fever. Other strains may cause a severe conjunctivitis with corneal involvement causing keratitis.
• Chlamydia presents with a chronic conjunctivitis in newborns and people who are sexually active.
• Infectious conjunctivitis is classified into three types:
• Hyperacute conjunctivitis is rare but severe conjunctivitis that develops very rapidly due to infection with gonorrhoea. It is the most serious cause of neonatal conjunctivitis but may also occur in sexually active adults.
• Acute infective conjunctivitis by definition lasts for no longer than 3 weeks. It may be caused by bacterial or viral infection.
• Chronic infective conjunctivitis by definition lasts longer than 3 weeks. It may be caused by bacteria when it is commonly associated with blepharitis or chlamydia.
• Neonatal conjunctivitis (previously called ophthalmia neonatorum) is defined as any conjunctivitis of the newborn that occurs within the first 28 days of life. It may be caused by infection or be a toxic response to topical treatments applied to the eye. The most important causes are gonorrhoea because it can result in a serious localized infection, and chlamydia which can be associated with the development of pneumonia.

[Yanoff and Duker, 2004]