Background: Streptococcus is a common source of bacterial keratoconjunctivitis in adults. Affected patients often report decreased vision, foreign body sensation, redness, and a mucous discharge. Clinical signs reveal diffuse conjunctival injection, a conjunctival papillary response, corneal superficial punctate keratitis, and a mucopurulent discharge with corresponding visual acuity decrease. Culturing is mandatory in hyperacute cases and broad-spectrum treatment is advised until culture results are definitive. Recurrent cases may change in clinical appearance. Bacterial exotoxins may induce a severe inflammatory response as well.
Case report: A case of bilateral recurrent bacterial keratoconjunctivitis in a 61-year-old man is reported, as well as a current clinical review of the literature. Aerobic culture yielded Streptococcus pyogenes, a beta-hemolytic group A streptococcus. After unsuccessful broad-spectrum antibiotic treatment with several agents, culture and sensitivity testing confirmed the diagnosis and adjustment of the treatment plan accordingly was successful. During the following 10 years, there were six episodes in the left eye and three episodes in the right eye with resultant inflammation and comeal pannus. Recent repeat culture and sensitivity testing showed that the streptococcus had changed to an atypical presentation. The university laboratory reported the findings to the State Department of Public Health, as this was a nonrespiratory isolate of group A streptococcus.
Conclusion: Although culture is indicated in hyperacute bacterial keratoconjunctivitis, consider sensitivity testing in non-responsive cases. If the condition is recurrent and the clinical presentation appears different from previous episodes, suspect that the initial pathogen may be changing. Severe secondary inflammation may occur due to bacterial exotoxin reactions. Identification of the underlying causes is advised.