ACUTE BACTERIAL CONJUNCTIVITIS
Introduction
Acute conjunctivitis can be:
●
Bacterial
●
Viral
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Allergic
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Irritative/ chemical
Whilst acute bacterial conjunctivitis is usually easily diagnosed on clinical grounds,
milder cases can be difficult to distinguish from viral or allergic causes.
In most cases empiric treatment for bacterial infection is undertaken.
Caution should be taken when assessing at risk groups for serious causes, such as
gonococcus or trachoma. The important differentials of herpes infection or hypopyon
must also be kept in mind.
Epidemiology
●
Acute bacterial conjunctivitis is widespread throughout the world.
●
Outbreaks of gonococcal conjunctivitis have occurred in northern and central
Australia.
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Infection due to Chlamydia trachomatis (trachoma) continues to be a
significant public health concern in Aboriginal communities
It is a major cause of preventable blindness worldwide.
●
The epidemiology of acute bacterial conjunctivitis in Australia due to causes
other than trachoma and gonococcal infection is not well documented.
●
Infections are most common in children under five years of age and
incidence decreases with age.
Pathology
Organisms
The most common bacterial pathogens include:
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Haemophilus influenzae
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Streptococcus pneumoniae
Less commonly:
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Staphylococcus aureus
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Pseudomonas aeruginosa
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Neisseria gonorrhoeae
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Neisseria meningitidis
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Chlamydia trachomatis
Adenovirus is the commonest cause of viral conjunctivitis
Incubation period
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The incubation period for bacterial infection is usually 24–72 hours.
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In the case of trachoma incubation is 5–12 days.
Reservoir
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Humans.
Mode of transmission
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Infection is transmitted via contact with the discharge from the conjunctivae or
upper respiratory tract of infected persons.
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Neonates may acquire infection during vaginal delivery.
●
In some areas flies have been suggested as possible vectors.
Period of communicability
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It is infectious while there is discharge.
Susceptibility & resistance
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Everyone is susceptible to infection and repeated attacks due to the same or
different bacteria are possible.
●
Maternal infection does not confer
immunity to the child.
Clinical assessment
Left: Bacterial conjunctivitis. Right:
Viral conjunctivitis.
Left: Allergic conjunctivitis. Middle: Herpes Zoster Ophthalmicus with nasociliary
nerve involvement. Right: Flourescein stained cornea demonstrating a dendritic
ulcer.
Whilst acute bacterial conjunctivitis is usually easily diagnosed on clinical grounds,
milder cases can be difficult to distinguish from viral or allergic causes.
Before a diagnosis of “simple” bacterial conjunctivitis is assumed, important serious
causes, as well as important differentials should always be considered.
1.
High risk groups:
Important serious causes should be considered in high risk groups which
include Aboriginal populations and neonates.
Trachoma:
●
Important epidemiological considerations may alert the clinician to the
possibility to Chlamydia infection. In Australia this will include
Aboriginal populations in particular.
●
Trachoma should be suspected in the presence of lymphoid follicles
and diffuse conjunctival inflammation or trichiasis (inturned
eyelashes).
Neonates:
2.
●
Neonates are at higher risk for serious bacterial infection, such as
staphylococcus, gonococcus and meningococcus.
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(See also RCH guidelines)
Hypopyon:
●
3.
Predisposing foreign body:
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4.
Look for and rule out this serious condition, (see separate guidelines)
Ensure that the eye has no predisposing foreign bodies.
Slit lamp examination
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Slit lamp examination should be undertaken if herpetic infection or
foreign body is suspected.
●
Nasociliary involvement in patients with herpes zoster ophthalmicus
will make ocular involvement likely.
“Typical” bacterial infection results in:
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Ocular pain, or “grittiness”.
●
Photophobia
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Ocular inflammation
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Purulent discharge, (as opposed to the clear discharge of viral infection in
most cases).
●
Initial unilateral infection rapidly becomes bilateral due to cross contamination
(via fingers).
Sixty-four per cent of cases of acute bacterial conjunctivitis spontaneously remit
within 5 days. Symptoms may however last up to 14 days if untreated.
Investigations
Mild conjunctivitis is rarely investigated and is usually treated empirically.
Microscopic examination of a stained smear or culture of the discharge is required to
differentiate bacterial from viral or allergic conjunctivitis.
Swabs should be taken for culture and PCR testing when serious bacterial infection,
(Neisseria gonorrhoeae or Neisseria meningitidis), or trachoma is suspected. They
should also be taken in cases of neonatal infection.
Herpes infection can de diagnosed clinically via slit lamp examination.
Management
Whilst acute bacterial conjunctivitis is usually easily diagnosed on clinical grounds,
milder cases can be difficult to distinguish from viral or allergic causes. In most cases
empiric treatment for bacterial infection is undertaken.
1.
Irrigation:
●
Sterile saline irrigation, to clear purulent discharge
2.
Discharging eyes should never be padded.
3.
Analgesics:
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4.
Anti-irritant drops:
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5.
Simple oral analgesics may give some relief from pain.
Topical vasoconstrictors such as phenylephrine 0.12% may provide
some symptom relief
Antibiotic drops: 2
Chloramphenicol:
●
Chloramphenicol 0.5% eye drops, 1 to 2 drops every 2 hours initially,
decreasing to 6-hourly as the infection improves.
●
Chloramphenicol 1% eye ointment may be used at bedtime
Alternatively:
Framycetin:
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Framycetin 0.5% eye drops, 1 to 2 drops every 1 to 2 hours initially,
decreasing to 8-hourly as the infection improves.
Gentamicin, tobramycin and quinolone eye drops are also available however
are substantially more expensive than the recommended drugs and are
generally unnecessary for uncomplicated empirical treatment.
Neisseria gonorrhoeae or Neisseria meningitidis require treatment with
systemic antibiotics. Specialist advice must be obtained for these ocular
infections.
Trachoma also requires systemic antibiotics, erythromycin or Azithromycin,
(see Therapeutic Antibiotic Guidelines for full prescribing details).
6.
Do not use,
●
Topical steroids
●
Topical local anaesthetics
in the treatment of bacterial conjunctivitis.
7.
Referral:
Referral to an Ophthalmologist should occur in the following circumstances:
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Failure of resolution with adequate treatment.
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Impairment of vision.
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Herpetic infection
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Suspected or proven Gonococcal or Neisseria infection
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Suspected or proven Chlamydia infection
Neonatal conjunctivitis should be referred to a pediatrician.
References
1.
The Blue Book Website.
2.
Therapeutic Antibiotic Guidelines, 13th ed 2006
Dr J. Hayes
8 October 2009