Case of keratitis caused by Streptomyces thermocarboxydus

We describe a case of keratitis caused by Streptomyces thermocarboxydus and report the usefulness of molecular analysis in identifying the exact species of Streptomyces. A 50-year-old man was diagnosed with keratitis caused by Streptomyces sp. which was identified as S. thermocarboxydus by sequencing the 16S rDNA. He had no history of trauma or systemic diseases. He was initially treated with topical beta-lactams and fluoroquinolones, and systemic beta-lactams but the keratitis did not improve. His vision improved significantly after topical erythromycin (5 mg/ml) and oral minocycline (200 mg/day) therapy. Our findings demonstrate that molecular analysis can be used to identify the exact Streptomyces species causing the keratitis. This then allowed us to determine the susceptibility of this species to different antibacterial drugs which were used to treat our patient successfully.