What Is Bacterial Conjunctivitis?

Bacterial conjunctivitis is an eye infection caused by bacteria, such as Staphylococcus aureus or Streptococcus pneumonia. Also known as pink eye, the disease causes eye discharge, redness, and itching. Although it rarely causes complications or permanent damage to the eye, patients often complain about discomfort due to the symptoms.

Pink eye happens when there is an inflammation or infection of the conjunctiva, the transparent membrane covering part of the eyeball and inner eyelid. The eye's blood vessels also become inflamed and more visible, causing eye redness. There are different types of conjunctivitis: viral, bacterial, and allergic conjunctivitis. 

Conjunctivitis is a common eye problem that affects nearly six million people in the United States every year. Bacterial pink eye is the second most common type, after viral conjunctivitis, and accounts for 50% to 75% of conjunctivitis cases in children. This form of pink eye is highly contagious and spreads through poor hygiene or contact with other people or insects. 

Bacterial Conjunctivitis Symptoms

Bacterial conjunctivitis can affect one or both eyes. It can also start in one eye and then spread to the other.

Symptoms of bacterial conjunctivitis include:

• Redness in one or both eyes
• Eye tearing
• Itchiness of one or both eyes
• A gritty feeling in one or both eyes
• Thick, yellow-green discharge

Depending on the cause, some patients may have additional symptoms, such as eye pain and blurry vision.

Causes

The four most common bacteria that cause bacterial pink eye in the United States are Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

Bacterial conjunctivitis is highly contagious and can pass from person to person and hand-to-eye contact with contaminated objects. Changes in the usual bacteria that live on the conjunctiva can cause conjunctivitis. Bacteria can also spread by large respiratory droplets. Contact lenses that aren’t cleaned properly can also cause bacterial conjunctivitis.

Less commonly, sexually transmitted diseases (STD) can also lead to this form of pink eye. These cases are usually caused by Chlamydia trachomatis, which causes chlamydia, and Neisseria gonorrhoeae, which causes gonorrhea. If pregnant women are infected, it can infect the baby during birth and cause neonatal conjunctivitis. Symptoms can appear up to 14 days after birth.

Diagnosis

An eye care provider can usually determine what type of pink eye you have by asking about your medical history and symptoms and by performing an eye exam. They may also be able to diagnose your condition by phone based on a discussion about your symptoms.

As part of the eye exam, your eye care provider may also flip your upper lids to examine the palpebral conjunctiva (the lining of the eyelids). They may also use special drops or dye to examine the cornea and other tissues for damage and inflammation and determine if the cause is viral or bacterial.

Some tests your healthcare provider may use to determine the cause of your pink eye include:

• Slit lamp exam: A slit lamp is an instrument made up of a microscope and a high-energy beam of light. During this exam, an eye care provider shines a thin beam of light into your eye. This beam allows them to examine the entire eye.
• Visual acuity tests: This test checks to see how well you can read letters or symbols from 20 feet away, while covering one eye at a time. Your healthcare provider may perform this test to see how your pink eye is affecting your vision.
• Eye culture: If you have had conjunctivitis for more than two or three weeks and it has not gone away on its own or with the help of home treatments, your eye care provider may want to perform an eye culture. During this test, your eye care provider takes a sample of the cells on the inside of your eyelids with a cotton swab and sends it to a laboratory to be examined by a pathologist.

Treatment

Home Remedies

• Soak a clean washcloth in warm water then wring it out so it’s not dripping.
• Lay the damp cloth over your eyes and leave it in place until it cools.
• Repeat this several times a day, or as often as is comfortable.
• Use a clean washcloth each time so you don't spread the infection.
• Use a different washcloth for each eye if you have infectious pink eye in both eyes.

Most uncomplicated cases resolve within one to two weeks.

Antibiotics

Antibiotic treatment will be recommended if:

• The eye doesn't start clearing up in five days
• Your conjunctivitis is caused by gonorrhea or chlamydia
• You wear contact lenses
• Your conjunctivitis is accompanied by discharge like pus
• You are immunocompromised

Antibiotic eye drops or ointments are usually prescribed for these cases. With antibiotics, the symptoms may disappear in a few days.

When conjunctivitis is related to an STD, your healthcare provider may prescribe an oral antibiotic. Azithromycin has already been demonstrated as effective in the treatment of chlamydial conjunctivitis, while gonococcal conjunctivitis will often be treated with ceftriaxone.

When an infant has neonatal conjunctivitis, healthcare providers will treat it immediately with erythromycin ophthalmic ointment.

Lifestyle Changes

To avoid spreading bacterial pink eye and speed up recovery, people who have the condition should avoid crowded places and take time off of school or work while they are symptomatic.

They should also practice proper hygiene by:

• Washing hands after touching eye secretions
• Avoid touching their eyes (especially the non-infected eye after touching the infected eye)
• Avoid swimming pools
• Avoid shared towels and pillows
• Use a fresh towel daily
• Wash pillowcases often 
• Throw away eye makeup, such as mascara

If you wear contact lenses, your healthcare provider will likely suggest that you stop using them throughout treatment. If you use hard lenses, ask if cleaning them thoroughly will be enough or whether you need to throw them away and replace them. Disposable contact lenses should be thrown away and replaced, but not worn until treatment is complete.

Complications

At-home treatments are usually recommended first. People may use over-the-counter artificial tears and ointments, as well as apply a warm compress over their eyes to relieve symptoms of bacterial pink eye. To make a warm compress:

You should see a healthcare provider immediately if you experience symptoms that are not typical with pink eye, including:

• Eye pain
• Blurred vision
• Photophobia (light sensitivity)

Complications from bacterial conjunctivitis are uncommon; however, severe infections can result in keratitis, corneal ulceration and perforation, and blindness. If you experience any of the above symptoms or changes to your vision, seek medical assistance right away.

Prognosis

Even though pink eye can be annoying and feels like it heavily affects the eye, it rarely affects people’s vision. Bacterial conjunctivitis will often resolve on its own.

A Word From Verywell

Bacterial conjunctivitis often causes eye discomfort, but typically does not affect vision. The disease is easily treated at home, and the symptoms can be relieved with artificial tears and ointments. People often start to feel improvement after a few days. Basic hygiene is vital to avoiding the spread of bacterial conjunctivitis. Simple measures such as avoiding touching your eyes and washing your hands often are essential while you still have symptoms.