Intrastromal Antibiotic Injection in Polymicrobial Keratitis: Case Report and Literature Review

Bacterial keratitis (corneal infection) caused by more than one organism is rare and exceedingly difficult to treat due to variable antibiotic susceptibilities. Intrastromal injections of antibiotics may be necessary to achieve higher drug concentrations at the site of infection, particularly in the case of deep stromal disease refractory to topical therapy. However, while this approach is increasingly used for fungal keratitis, there is a paucity of the literature regarding the use of intrastromal antibiotics bacterial keratitis. In the current case, an 86-year-old patient presented with a left corneal ulcer with corresponding microbiologic cultures positive for Staphylococcus epidermidis, Staphylococcus aureus, and Achromobacter species. The ulcer continued to progress despite maximal topical antibiotic treatment yet demonstrated marked improvement after two intrastromal injections of moxifloxacin administered 2 weeks apart. Polymicrobial keratitis can be particularly challenging to eradicate despite maximal topical antibiotic therapeutics. Intrastromal corneal injections provide a mechanism for drug delivery directly to the site of infection and thus may represent an important alternative in refractory cases.