Bacterial Conjunctivitis

BACTERIAL CONJUNCTIVITIS

Pathogenesis/Pathophysiology

The surface of the eye (and the inner surface of the eyelids) is covered by tissue called the conjunctiva. This layer is colonized by normal flora including streptococci, staphylococci, haemophilus and Cornyebacterium species. However, in instances where there are changes—either through contamination from the environment, spread from nearby areas or through the circulatory system—in the individual’s immune system or in the types of bacteria, conjunctivitis could develop. Inflammation of the conjunctiva causes conjunctivitis (or sore eye or pinkeye), and in bacterial conjunctivitis (BC), there is bacterial infection of the conjunctiva, causing the signs and symptoms noted. It could range from a self-limited disease to severe systemic disease.

Risk factors for the development of BC include exposure to infected individuals and sexually transmitted disease at birth and immunodeficiency states.

Epidemiology

BC is common in the United States and the world. Most people will have this condition at least once in their life. Of all cases of conjunctivitis, around 54%-73% are BC. Community outbreaks could be overwhelming, with some cases causing blindness in newborns.

Signs symptoms

History should involve extensive inquiry on the individual’s age and social habits. It is important to note that BC could develop even in healthy individuals. Problems with resistance should be suspected in the elderly with BC, and other sources of infection should be sought. Venereal disease should be asked in those who are sexually active , especially if BC is associated with abundant purulent discharge and severe redness (injection) and edema (chemosis).

The duration of the disease and medications taken at home should be asked. Exposure to people who had BC should also be asked. Systemic conditions (such as diabetes) and medications being taken could is also important in determining the management and prognosis of the disease. Use of contact lens could also bring about BC.

Individuals complain of redness (hyperemia), irritation (chemosis) and watering (epiphora) of the eyes.

BC caused by bacteria that produce pus causes a granular sensation and mucopurulent discharge that is greyish or yellowish, causing the eyelids to be stuck together, especially after waking up. Crusting of the eye and the skin around it could also be noted. However, it is important to note that redness and discharge is not always present in BC. The gritty sensation in the eye could be mistaken for a foreign body. Severe pain could be present in acute pyogenic infections. The infection is usually present in one eye, and the other eye gets affected after a few days.

On physical examination, there is conjunctival injection, usually of papillary pattern on slit lamp examination. Discharge is characteristically purulent, causing matting of the lids. Lymphadenopathy in the preauricular area is not common but could be found in severe cases caused by N gonorrhoeae. There is eyelid edema, usually mild. Visual acuity is not affected except for blurring due to the discharge. There is normal papillary reaction. Slit lamp examination also demonstrates an anterior chamber with no visible cells and normal vitreous.

Diagnosis

Laboratory evaluation for BC could include conjunctival swabs sent for Gram stain and cultures, especially if there is no response to empiric therapy. Imaging studies have no role in the diagnosis of BC, but is usually utilized for ruling out other conditions.

Treatments

BC could resolve without treatment. Therapy—including eye drops, ointments or oral medications—may be started if there is no improvement after 3 days of symptom onset. Eye drops have the advantage of not affecting vision, while ointments allow for longer contact of the drug with the conjunctiva. Systemic antibiotics are usually required for N gonorrhoeae and chlamydial infections.

Doctors usually prescribe broad-spectrum topical antibiotics as empiric treatment. First-line antibiotics include sodium sulfacetamide, gentamicin, tobramycin, neomycin, trimethoprim and polymyxin B combination, ciprofloxacin, ofloxacin, gatifloxacin, and erythromycin.

Newborns with chlamydial infection may be treated with erythromycin, while the mother is given doxycycline. On the other hand, newborns with N gonorrhoeae infection may be treated with aqueous penicillin G, while the mother is given ceftriaxone and doxycycline. Opthalmia neonatorum prophylaxis against ophthalmia neonatorum is routinely given in newborns.

Complications

BC rarely causes complications but could cause formation of membranes and scarring of the punctum, ulcers in the cornea and symblepharon (adhesion of the conjunctiva of the eyelid to the conjunctiva of the eyeball). Endophthalmitis could ensue in eyes with prior intraocular surgery.

Deaths in individuals with BC are usually caused by underlying conditions that are not recognized and/or treated such as meningitis and sepsis. BC in newborns could bring about pneumonia or otitis media. The symptoms caused by BC could cause absences from school and work.

Prevention

Proper hygiene, especially of the hands and face, and avoidance of contact with infected individuals are important in preventing the spread of BC.

References:

Buznach N, Dagan R, Greenberg D. Clinical and bacterial characteristics of acute bacterial conjunctivitis in children in the antibiotic resistance era. Pediatr Infect Dis J. 2005 Sep;24(9):823-8.

Marlin DS. Medscape: Conjunctivitis, Bacterial. Retrieved from http://emedicine.medscape.com/article/1191730-overview on March 26, 2011.

Wikipedia. Conjunctivitis. Retrieved from http://en.wikipedia.org/wiki/Conjunctivitis on March 26, 2011.

Wrong Diagnosis. Bacterial conjunctivitis. Retrieved from http://www.wrongdiagnosis.com/b/bacterial_conjunctivitis/intro.htm on March 26, 2011.

Netdoctor. Conjunctivitis (inflammation of the eye). Retrieved from http://www.netdoctor.co.uk/diseases/facts/conjunctivitis.htm on March 26, 2011.

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