• Summary
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• Background
• Clinical Diagnosis
• Investigation
• Treatment
• Non-Antimicrobial Treatment
• Empirical Antimicrobial Treatment
• Directed Antimicrobial Treatment (when microbiology results are known)
• Duration of Treatment
• Treatment Failure

History
Rapid onset, red, gritty, sticky eyes, usually bilateral but may be sequential.
Close contact with another infected person is common, eyes are often glued together by discharge after sleep, usually starts in one eye then spreads to the other.

Examination
Assess for purulent discharge with crusty lids, diffusely injected conjunctiva.
Lymph nodes in front of the ear.

Exclude other serious causes of a red eye – see diagnosis section of full guideline, then
Assess if:
Hyperacute: (rare) sudden onset (12-24 hours) and rapid progression of profuse discharge (usually young adults), preauricular lymphadenopathy often present.
Acute: symptoms for no longer than 3 weeks – acute infection may be severe or non severe - based on the degree of pain and redness of the eye(s)
Chronic: symptoms for longer than 3 weeks.

Investigations
For hyperacute or persistent conjunctivitis an eye swab is required for routine culture and an APTIMA swab for gonococcal and Chlamydia PCR.
For acute conjunctivitis a swab is unnecessary.

Non-antimicrobial treatment

• Patients with contact lenses should remove lenses until all symptoms of infection have resolved and for at least 24 hours after the treatment has been completed.
• Lubricant eye drops/gel to reduce discomfort. (Oxyal, Liquifilm or Celluvisc 1% Carbomer 0.2% eye gel three to four times a day is a suitable lubricant.
• Secretions from the lid and lashes should be removed with cotton wool soaked in water.

Antimicrobial treatment
Topical antimicrobials should not be routinely used for acute conjunctivitis because it is a self-limiting disease.  Review inpatients (or advise outpatients to return if no better) in 3 days.
For severe acute infection (judged clinically) chloramphenicol 0.5% eye drops or chloramphenicol 1% eye ointment is first line empirical treatment.
Fusidic acid ophthalmic drops are used in patients who are allergic/intolerant to chloramphenicol, are pregnant, have a personal or family history of blood dyscrasias.

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Bacterial conjunctivitis is usually a self-limiting condition which resolves within 2 weeks.  It is most commonly caused by Staphylococcus species, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. 
It can be quite difficult to differentiate bacterial from acute viral conjunctivitis and many doctors treat all cases of acute infective conjunctivitis as bacterial on clinical grounds.
Gonorrhoea (hyperacute conjunctivitis) and Chlamydia (chronic conjunctivitis) may be cause infection in sexually active patients.

Infectious conjunctivitis is classified into three types:

• Hyperacute conjunctivitis is a rare but severe conjunctivitis that develops very rapidly due to infection with Neisseria gonorrhoeae or occasionally Neisseria meningitidis. It is characterised by the development of a copious, purulent discharge over 12 to 24 hours. It is the most serious cause of neonatal conjunctivitis but may also occur in sexually active adolescents and young adults.  These patients should be referred urgently to ophthalmic specialists because infection can rapidly progress to ulceration and perforation (within 24 hours).
• 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 is commonly associated with blepharitis and Chlamydia infection.  One occasional cause of chronic conjunctivitis is molluscum contagiosum.

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Conjunctivitis presents as an acute, red, gritty, sticky eye(s), usually bilateral but may be sequential; purulent discharge with crusty lids and diffusely injected conjunctiva.  The rapidity of progression and severity of symptoms determines classification, treatment and investigation - see background.

With a unilateral red eye it is important to exclude serious causes e.g. glaucoma, keratitis and iritis.  These should be suspected if any of the following features occur.

• Moderate to severe pain or photophobia,
• Marked redness of the eye in one eye.  The greater the redness, the more likely that the cause is serious. Ciliary injection, which is not always obvious, occurs with inflammation of deeper structures. It is indicated by redness and dilated blood vessels seen between the white of the eye and the iris.
• Reduced visual acuity as measured on a Snellen chart.

Any patient with conjunctivitis who is suspected to have Stevens-Johnson syndrome must be referred immediately to an ophthalmic specialist.
If there are NO features to suggest a serious cause of red eye exclude:-

• Superficial corneal injury.  Usually a history of trauma and an abrasion may be seen with fluorescein staining.
• Subconjuctival haemorrhage.  Apart from redness there are no other abnormal findings and the redness is well demarcated, does not cover the cornea and obliterates conjunctival blood vessels.
• Irritant conjunctivitis, which is usually associated with an identified mechanical or irritant cause.
• Allergic conjunctivitis.  This is usually associated itching and is recurrent following exposure to a known allergen.

The characteristic features of conjunctivitis are:-

• Close contact with another infected person
• Symptoms of upper respiratory tract infections are present.
• The eyes are glued together by discharge after sleep, or mucopurulent discharge is seen on examination.
• Conjunctivitis starts in one eye then spreads to the other.
• An enlarged lymph node in front of the ear is identified.

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Recommendation: For acute bacterial conjunctivitis swabs for microbiological investigation are unnecessary.  However swabs of the eye are recommended in hyper acute and chronic conjunctivitis to identify the infective cause.
[Evidence level C]

Recommendation: In hyperacute conjunctivitis: send a swab for microscopy and bacterial culture and an APTIMA swab for gonococcal PCR and a swab in viral transport medium for viral PCR.
[Evidence level C]

Recommendation: In chronic conjunctivitis send a swab for bacterial culture and an APTIMA swab (APTIMA) for Chlamydia PCR.
[Evidence level C]

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Recommendation: Patients with contact lenses should remove their lenses until all symptoms of infection have resolved and for at least 24 hours after the treatment has been completed.
[Evidence level C]

Recommendation: Lubricant eye drops or gel can reduce discomfort. (Oxyal, Liquifilm or Celluvisc 1% or Carbomer 0.2% eye gel three to four times a day are suitable lubricants).
[Evidence level C]

Recommendation: Secretions from the lid and lashes should be removed with cotton wool soaked in water.
[Evidence level C]

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Recommendation: topical antimicrobials should not be routinely used for non-severe acute conjunctivitis.
[Evidence level A]

Recommendation: patients not prescribed topical antimicrobials should be advised to return or be reviewed in 3 days if symptoms are worse or no better.
[Evidence level C]

Recommendation: For acute conjunctivitis requiring treatment first line therapy is chloramphenicol 0.5% eye drops (initially one drop is instilled into the affected eye(s) every 2 hours for 2 days, and then every 4 hours for 5 days) OR 1% eye ointment (applied four times a day for 2 days then twice a day for 5 days.)
[Evidence level C]

Recommendation: For patients who are allergic/intolerant to chloramphenicol, are pregnant, have a history, or family history of blood dyscrasias,  fusidic acid is an alternative.  A 7 day course is recommended.
[Evidence level C]

Recommendations:  For hyperacute conjunctivitis first line treatment is Ceftriaxone 2g 24-hourly IV.  A single dose without corneal involvement or for 3 days if cornea is involved.

Justification
Bacterial conjunctivitis is usually a mild self-limiting disease with most patients being symptom free without treatment in one to two weeks. 
In a Cochrane review, Meta-analysis of early (days 2 to 5) and late (days 6 to 10) clinical and microbiological outcomes revealed that topical antibiotics are of benefit in improving early clinical (RR 1.36, 95% CI 1.15 to 1.61) and microbiological (RR 1.55, 95% CI 1.37 to 1.76) remission. Modest benefits were still conferred for late clinical (RR 1.21, 95% CI 1.10 to 1.33) and microbiological (RR 1.37, 95% CI 1.24 to 1.52) remission. No serious adverse outcomes were reported in either the active or placebo arms of the trials1. The authors conclude that although conjunctivitis is a self-limiting condition, the use of antibiotics is associated with modestly improved rates of clinical and microbiological remission compared to placebo.
There is further evidence that delaying treatment by 3 days and only prescribing if symptoms persist produces no difference in duration of moderate symptoms (3.3 days [risk ratio 0.7, 95% confidence interval 0.6 to 0.8], delayed antibiotics 3.9 days [0.8, 0.7 to 0.9]), but reduces antibiotic use2.
Clinical Knowledge Summary (CKS) recommend that as most patients get better without treatment, complications are low and 10% of patients suffer adverse reactions to treatment that antibiotics should only be provided if:-

• Conjunctivitis is severe or likely to be severe providing serious causes of red eye can be excluded.
• Despite the limitations the patient still prefers treatment.

In conclusion if conjunctivitis is mild it is worth not treating with antibiotics prescribing lubricants and counselling patients on hygienic measures to prevent spread with a proviso to return if symptoms do not improve in 3 days.  For moderate to severe symptoms treatment should be prescribed.

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When the results of microbiology samples are known it may be necessary to… amend therapy. Discuss with Microbiology as necessary.
Neisseria gonorrohoea or Neisseria meningitidis isolated - treat according to recommendations for hyperacute conjunctivitis.

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Acute conjunctivitis: 1 week.
Hyperacute conjunctivitis - see empirical treatment section.

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If conjunctivitis persists for more than two weeks the patient must be re-evaluated.  Swabs for bacteria and Chlamydia must be taken.  Treatment will depend on results of the swabs.  If Chlamydia is present the patient must be referred to a sexually transmitted disease clinic for systemic treatment and contact testing.
For chronic conjunctivitis refer to an ophthalmologist.  N.B. Molluscum contagiosum will not resolve until the lesion is removed.

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