Bacterial conjunctivitis is inflammation of the conjunctiva caused by direct contact with infected secretions. The most common organisms are Staphylococcus species, S. pneumonia, H. influenzae, and M. catarrhalis.
It presents with conjunctival injection, mucopurulent discharge, and crusty eyelids. The diagnosis is usually clinical. The condition is often self-limiting, but there is good evidence that antibiotics improve remission rates. Most of the current evidence suggests that the choice of topical antibiotics and the treatment regimen do not significantly affect the rate of recovery from infection. Failure to recognise and treat bacterial conjunctivitis may lead to complications, such as keratitis or anterior uveitis.
The aetiology of the condition is most commonly Staphylococcus species in adults, and Streptococcus pneumonia and the Gram-negative organisms Haemophilus influenzae and Moraxella catarrhalis in children. Contact lens wearers are at particular risk for Gram-negative infections such as Pseudomonas aeruginosa. Neisseria gonorrhoeae is primarily a neonatal aetiology.
It is feared that it may be easily spread in day care centres and school classrooms, leading to absences and lost time from work for parents.
The most common causes of conjunctivitis are bacterial and viral infections. In the primary care setting, treatment is based solely on the clinical examination.
Its prevalence is significant to the general population, because it is a leading cause of day care and school absences. Even though most cases of bacterial conjunctivitis are self-limited, it can take up to three weeks for the infection to clear. Treatment of acute conjunctivitis helps to shorten the clinical course, reduces spread of the contagion and discomfort, and allows the patient to resume activities earlier.
The aetiology is difficult to delineate on clinical grounds alone, and there is much pressure on physicians to prescribe antibiotics due to the social impact the diagnosis holds. Thus, physicians are faced with the dilemma of potentially overprescribing antibiotics in an era of increasing bacterial resistance and increased awareness of cost.
One recent study estimates an annual incidence rate of 135 per 10 000 in the US.
The same study found the estimated total direct and indirect cost of treating bacterial conjunctivitis in the US to be $589 million annually. Accounting for a 20% variation in annual incidence rate and treatment cost resulted in an estimated cost range of $377 to $857 million per year.
The study found that topical antibiotics expedite recovery from bacterial conjunctivitis. The choice of antibiotic usually does not affect outcome.
Assessment should include:
- Redness, foreign body sensation and purulent/ mucopurulent discharge are common complaints; there may be itching, chemosis, or conjunctival papillae
- Ask about contact lens wear
- Assess for corneal involvement and intraocular involvement
- Conjunctival swabs can be done for Gram stain, culture, and sensitivity to clarify diagnosis, particularly in more severe or refractory cases
- Moderate to severe eye pain, photophobia, or change in visual acuity should raise suspicion for more serious causes.
Most cases of acute infectious conjunctivitis are self-limited and 64% resolve in 2-5 days. Untreated, acute bacterial conjunctivitis is clinically cured within 3-5 days in 28% of cases, and by 8-10 days there is a 72% clinical cure rate. There is bacteriologic cure of 19% and 31% of the same untreated groups. If treated with antibiotics, these numbers improve to 62% clinical cure at 3-5 days and 91% at 8-10 days, with bacteriologic cure of 71% and 79%, respectively. Recent studies have shown that topical antibiotics impact microbiologic remission by 6-10. Thus, there is support for treating bacterial conjunctivitis because it leads to more rapid and improved rates of clinical remission.