A staph infection in the eye originates from Staphylococcus aureus, a common bacterium found on human skin and in the nose. While often harmless, this bacterium can lead to various eye infections if it multiplies or enters the eye, especially through a break in the skin or mucous membranes. These infections can affect different parts of the eye, including the eyelids, conjunctiva, cornea, and tear ducts. Staphylococcus aureus is a frequent cause of conditions like conjunctivitis, styes, and blepharitis.
MRSA Versus Other Eye Infections
Methicillin-resistant Staphylococcus aureus, or MRSA, is a specific strain of Staphylococcus aureus that has developed resistance to common antibiotics, including methicillin and other penicillin-related drugs. This resistance makes MRSA infections more challenging to treat compared to typical bacterial eye infections. Unlike standard bacterial conjunctivitis or a simple stye that might respond to conventional antibiotics, MRSA eye infections often persist or worsen without targeted treatment.
MRSA can cause a similar range of eye infections as other Staphylococcus aureus strains, including conjunctivitis, keratitis (cornea inflammation), and preseptal cellulitis (eyelid infection). However, its resistance to common antibiotics, such as penicillin or cephalosporins, means specialized treatments are necessary to clear the infection and prevent complications.
Symptoms of an Ocular MRSA Infection
An ocular MRSA infection can manifest with several noticeable physical signs. Individuals may experience severe redness and swelling around the affected eye. Significant pain or a burning sensation in the eye is commonly reported.
Thick, often yellow or green, pus or discharge may be present, sometimes leading to crusting of the eyelids, especially upon waking. A painful lump on the eyelid, resembling a stye or abscess, can also develop. Increased sensitivity to light and blurred or decreased vision are also possible. Symptoms often appear rapidly and can be more severe than other eye infections.
Transmission and Prevention
MRSA primarily spreads through direct contact with an infected person or contaminated surfaces. For ocular infections, this often involves touching an infected area on the body and then touching the eye, or coming into contact with objects that harbor the bacteria. Contaminated items such as towels, pillowcases, shared makeup, or improperly cleaned contact lenses can facilitate transmission. MRSA is also prevalent in community settings where close skin-to-skin contact occurs, such as gyms or schools, and in healthcare environments.
Preventing MRSA spread to the eye involves several measures. Frequent handwashing with soap and water for at least 20 seconds is important, especially after touching public surfaces or before touching the face. Avoid sharing personal items like towels, washcloths, razors, and eye makeup. Proper contact lens hygiene, including cleaning and replacing lenses as advised, is also crucial. Also, avoid touching or rubbing the eyes, especially with unwashed hands.
Diagnosis and Treatment Protocols
Diagnosis of an ocular MRSA infection begins with a physical examination. To confirm MRSA, a sample of discharge or tissue from the infected eye is collected. This sample is sent to a laboratory for culture testing to identify the specific bacterial strain and its antibiotic susceptibility. Newer tests can detect Staphylococcus aureus DNA within hours, speeding diagnosis.
Once MRSA is confirmed, treatment involves specialized antibiotics to which the strain is susceptible. Topical antibiotic eye drops or ointments, such as chloramphenicol or vancomycin, are prescribed for localized infections. For more severe or widespread infections, oral antibiotics like doxycycline, azithromycin, Bactrim, or clindamycin are necessary. If an abscess has formed, a doctor may need to drain it alongside antibiotics. Completing the full course of prescribed antibiotics, even if symptoms improve, is crucial to eradicate the infection and prevent further antibiotic resistance.
Potential Complications of Untreated Infections
Delaying or avoiding treatment for an ocular MRSA infection can lead to serious complications. The infection may spread from superficial parts of the eye to deeper tissues, such as orbital cellulitis (an infection around the eye socket). Untreated infections can also result in corneal ulcers (open sores on the clear front surface of the eye).
These ulcers can cause permanent scarring and significantly impair vision. In severe cases, infection of inner eye structures can lead to permanent vision damage or even loss. Prompt medical attention is necessary to prevent these outcomes and preserve vision.