Bacterial Conjunctivitis

In the UK, the commonest organisms to cause conjunctivitis are the pneumococcus, Haemophilus spp. and Staphylococcus aureus. The last mentioned is normally associated with chronic lid infections, and the acute purulent conjunctivitis, known more familiarly as "pink eye", is usually caused by the pneumococcus. Chronic conjunctivitis can also be caused by Moraxella lacunata but this organism is rarely isolated from cases nowadays. An important but rare form of purulent conjunctivitis is that caused by Neisseria gonorrhoeae; this is still an occasional cause of a severe type of conjunctivitis seen in the newborn babies of infected mothers. Untreated, the cornea also becomes infected, leading to perforation of the globe and perma-

Figure 6.2. Ophthalmia neonatorum.

nent loss of vision. Purulent discharge, redness and severe oedema of the eyelids are features of the condition, which is generally known as ophthalmia neonatorum (Figure 6.2). Ophthalmia neonatorum can also be caused by staphylococci and the chlamydia (see inclusion conjunctivitis of the newborn). The disease is notifiable and any infant with purulent discharge from the eyes, particularly between the second and twelfth day postpartum, should be suspect. At one time, special blind schools were filled with children who had suffered ophthalmia neonato-rum. An active campaign against this cause of blindness began at the end of the last century when Carl Crede introduced the principle of careful cleansing of the infant's eyes and the instillation of silver nitrate drops. Blindness from this cause has now disappeared in the UK but there is still a low incidence of ophthalmia neonatorum. Those affected require treatment with both topical medication (e.g., chloram-phenicol 0.5% eye drops) and intramuscular benzylpenicillin (a cephalosporin, such as cefotaxime, is an alternative). Both parents of the child should also be assessed.

Pink eye is the name given to the type of acute purulent conjunctivitis that tends to spread rapidly through families or around schools. The eyes begin to itch and within an hour or two produce a sticky discharge, which causes the eyelids to stick together in the mornings. If the disease is mild, it can be treated by cleaning away the discharge with cotton-wool, and it does not usually last longer than three to five days. More severe cases might warrant the prescription of antibiotic drops instilled hourly during the day for three days followed by four times daily for five days. A conjunctival culture should be taken before starting treatment. Commonsense precautions against spread of the infection should also be advised, although they are not always successful.

Attempts to culture bacteria from the conjunc-tival sac of cases of chronic conjunctivitis do not yield much more than commensal organisms.

One particular kind of chronic conjunctivitis in which the inflammation is sited mainly near to the inner and outer canthi is known as angular conjunctivitis with follicles on the superior tarsal conjunctiva. Another feature of this is the excoriation of the skin at the outer canthi from the overflow of infected tears. The clinical picture has been recognised in association with infection by the bacillus M. lacunata. Often, zinc sulphate drops and the application of zinc cream to the skin at the outer canthus are sufficient treatment in such cases. Tetracy-cline ointment might be more effective.

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