Bacterial Conjunctivitis

From EyeWiki

Bacterial conjunctivitis is one of the most commonly encountered eye problems in medicine. Most cases are acute, self-limited, and not a major cause of morbidity. However, because of its high prevalance, it has a large societal impact in terms of missed days of school or work. Antibiotics can hasten the resolution of symptoms and microbial eradication and are therefore typically used to allow patients to return to their daily activities faster and to decrease the spread of disease.

Chronic and hyperacute forms of bacterial conjunctivitis, typically due to Chlamydia trachomatis and Neisseria, respectively, are entirely different entities that are associated with high levels of ocular and systemic morbidity. This page will focus primarily on acute forms of bacterial conjunctivitis.

Disease Entity

2010 ICD-9

  • 372.00 Acute Conjunctivitis unspecified
  • 372.01 Serous conjunctivitis except viral
  • 372.03 Other mucopurulent conjunctivitis
  • 372.04 Pseudomembranous conjunctivitis

2010 ICD-10

  • H10.3 Acute conjunctivitis, unspecified
  • H10.023 Other mucopurulent conjunctivitis, bilateral


Bacterial conjunctivitis is an infection of the eye's mucous membrane, the conjunctiva, which extends from the back surface of the eyelids (palpebral and tarsal conjunctiva), into the fornices, and onto the globe (bulbar conjunctiva) until it fuses with the cornea at the limbus.


Acute bacterial conjunctivitis is primary due to Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. Other pathogens responsible for acute disease are Pseudomonas aeruginosa, Moraxella lacunata, Streptococcus viridans, and Proteus mirabilis. These organisms may be spread from hand to eye contact or through adjacent mucosal tissues colonization such as nasal or sinus mucosa.

Hyperacute conjunctivitis is primarily due to Neisseria gonorrhoeae, which is a sexually transmitted disease. Neisseria meningitidis is also in the differential and is important to consider as it can lead to potentially fatal meningeal or systemic infection. 

Chronic conjuctivitis is primarily due to Chlamydia trachomatis. However, chronically ill, debilitated, or hospital patients can become colonized with other virulent bacteria responsible for chronic conjunctivitis. Staphylococcus aureus and Moraxella lacunata may also cause chronic conjunctivitis in patients with associated blepharitis.

Risk Factors

  • Since these bacteria are usually spread from other infected inviduals, poor hygenic habits may increase the risk of infection 
  • Poor contact lens hygiene
  • Contaminated cosmetics
  • Crowded living or social conditions such elementary schools, military barracks etc
  • Ocular diseases including dry eye, blepharitis, and anatomic abnormalities of the ocular surface and lids
  • Recent ocular surgery, exposed sutures or ocular foreign bodies
  • Chronic use of topical medications
  • Immune compromise
  • Neonates are at particularly high risk for conjunctivitis, and this entity is discussed elsewhere in the Neonatal Conjunctivitis article.



  • Red eye: Either unilateral, bilateral, or sequentially bilateral
  • Discharge: Classically purulent, but may be thin or thick, muco-purulent or watery
  • Irritation, burning, stinging, discomfort
  • Tearing
  • Light sensitivity
  • Intolerance to contact lens
  • Fluctuating or decreased vision


  • Bulbar conjunctival injection
  • Palpebral conjunctival papillary reaction
  • Muco-purulent or watery discharge
  • Chemosis
  • Lid erythema
  • Conjunctival membranes

Diagnostic procedures

  • In the majority of cases it is a clinical diagnosis and does not require Gram stain or cultures.
  • A rapid antigen test for adenovirus is available for in-office use[1].
  • Gram stain & Cultures in Chocolate and blood agar: Primarily used in cases of atypical conjunctivitis such as hyperacute or chronic/non-responding as well as in neonatal conjunctivitis.
  • Viral culture or PCR can help differentiate viral versus bacterial conjunctivitis if clinical diagnosis is unclear.

Differential diagnosis

  • Acute viral conjunctivitis
  • Blepharoconjunctivitis
  • Allergic conjunctivitis
  • Atopic conjunctivitis
  • Vernal conjunctivitis
  • Toxic and chemical conjunctivitis
  • ocular mucus membrane pemphigoid
  • graft versus host disease
  • Anterior uveitis, episcleritis, scleritis

Viral conjunctivitis is much more common than bacterial conjunctivitis. It can be difficult to differentiate from bacterial conjunctivitis and they can coexist as viral conjunctivitis with bacterial superinfection. The RPS Adenodetector can be used to identify some strains of adenovirus responsible for infection.

The signs on ophthalmic exam which suggest viral over acute bacterial are as follows:

  • Follicular reaction
  • Pre-auricular lymphadenopathy
  • Watery discharge
  • Itchy eyes
  • Concurrent pharyngitis, fever, and upper respiratory infection
  • A history of prior conjunctivitis

On the other hand, a history of mucopurulent discharge with "gluing" of the eyelids in the morning is predictive of bacterial conjunctivitis. [2].


Almost all cases of acute bacterial conjunctivitis are self-limited and will clear within 10 days without treatment. However, there are some more virulent organisms which may go on to cause chronic colonization and symptoms. Furthermore, antibiotic treatment has been shown to decrease the duration of symptoms and speed the eradication of microorganisms from the conjunctival surface. 

General treatment

Bacterial conjunctivitis is a contagious condition, so patients are instructed in proper hygiene and hand washing. The exact period of time of contagion cannot be predicted and the amount of time suggested varies, with a recent survey of ophthalmologists recommending 1 - 3 days away from work or until the infection clears.[3]

Supportive therapy for conjunctivitis consists of cool compresses and preservative free artificial tears two to six times daily. 

Medical therapy

Antibiotics may lead to quicker clinical and microbiological remission compared with placebo, at least in the first 2-5 days of therapy. This may result in decreased transmission of the disease and lower incidences within the population.[4]

Many antibiotics have been shown to be equivalent in the treatment of routine cases, and therefore the choice of antibiotics is often guided by cost, availability, and risk of side effects.

The most common antibiotics used for acute bacterial conjunctivitis are as follows:

  • Fluoroquinolones:
    • 2nd generation: Ciprofloxacin 0.3% drops or ointment, or Ofloxacin 0.3% drops
    • 3rd generation: Levofloxacin 0.5% drops
    • 4th generation: Moxifloxacin 0.5% drops, Gatifloxacin 0.5% drops, or Besifloxacin 0.6% drops
  • Aminoglycosides:
    • Tobramycin 0.3% drops
    • Gentamicin 0.3% drops
  • Macrolides:
    • Erythromycin 0.5% ointment
    • Azithromycin 1% solution
  • Other
    • Bacitracin ointment
    • Bacitracin/Polymixin B ointment
    • Neomycin/Polymixin B/Bacitracin
    • Neomycin/Polymixin B/gramicidin
    • Polymixin B/Trimethoprim
    • Sulfacetamide
    • Chloramphenicol (In much of the world, outside the US, this cheap, broad spectrum drop is the most prescribed ocular antibiotic. However, because chloramphenicol use, at least systemically, is associated with a potentially fatal side effect (aplastic anemia), this medicine is not available for topical use in the United States.)
    • Fusidic Acid (Common treatment in the UK; not used in the US)
  • Povidone-iodine 1.25% may be as effective as antibiotic drops if above antibiotics are unavailable[5].

For Neisseria gonorrhoeae and Chlamydia trachomatis, systemic antibiotics are necessary as follows:

  • Chlamydia:
    • Macrolides: Azithromycin (1gm single dose) or Erythromycin
    • Tetracyclines: Doxycycline or Tetracycline (Avoid in pregnant, nursing mothers)
    • Children less than or equal to 45 kg : Erythromycin 50 mg/kg/day PO divided into four doses daily for 14 days
  • Neisseria gonorrhoeae:
    • Ceftriaxone 250mg Intramuscular injection once + Azithromycin 1 gram PO once.
    • Doxycyline 100mg PO BID for 7 days
    • For cephalosporin allergy, Azithromycin 2g PO once
    • For Children < 18 years old: Ceftriaxone 125mg IM once OR Spectinomycin 40mg/kg IM once (max dose 2grams)

Medical follow up

Since the vast majority of cases run a benign course, most patients are given medication and then told to return for follow-up only if there is worsening or no improvement in symptoms.

Patients diagnosed with Chlamydia and Neisseria gonorrhea need closer follow up (1-2 days) given increased risk of corneal involvement and perforation. Patients also need to inform their partners and sexual contacts about their diagnosis so that they can be treated and re-infection avoided.

Additional Resources


  1. Sambursky R, Tauber S, Schirra F, Kozich K, Davidson R, Cohen EJ. The RPS adeno detector for diagnosing adenoviral conjunctivitis. Ophthalmology. 2006 Oct;113(10):1758-64. doi: 10.1016/j.ophtha.2006.06.029. PMID: 17011956.
  2. Rietveld RP, ter Riet G, Bindels PJ, Sloos JH, van Weert HC.Predicting bacterial cause in infectious conjunctivitis: cohort study on informativeness of combinations of signs and symptoms.BMJ. 2004 Jul 24;329(7459):206-10. Epub 2004 Jun 16.
  3. SK Webber, DGS Blair, AR Elkington, CR Canning. Ophthalmologists with conjunctivitis: Are they fit to work? EYE. 1999. 13; 650-652.
  4. Sheikh A, Hurwitz B. Antibiotics versus placebo for acute bacterial conjunctivitis. Cochrane Database Syst Rev 2006 Issue 2. Art No: CD001211. DOI: 10.1002/14651858.CD001211.pub2.
  5. Isenberg SJ, Apt L, Valenton M, et al. A controlled trial of povidone-iodine to treat infectious conjunctivitis in children. Am J Ophthalmol. 2002;134(5):681-688.
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