A microbiological and confocal microscopy study documenting a slime-producing Staphylococcus epidermidis isolated from a nylon corneal suture of a patient with antibiotic-resistant endophthalmitis

Background: We describe a case of posttraumatic endophthalmitis unresponsive to systemic (amoxicillin+clavulanic acid and piperacillin/tazobactam), intra-ocular (vancomycin) and topical (ofloxacin, tetracycline and sulfametoxazole) antibiotic therapy. Microbiological and confocal microscopy studies of a nylon corneal suture revealed the presence of a slime-producing strain of Staphylococcus epidermidis. Methods: We describe the history and clinical presentation of a 77-year-old man in whom a high-grade posttraumatic endophthalmitis resolved only after the removal of a single nylon corneal suture. Microbiological investigations of the aqueous, vitreous and suture were performed, and the propensity of the suture-associated isolate to form biofilm was assessed using confocal microscopy. Results: A single stain of S. epidermidis was isolated from both aqueous and vitreous specimens and from the suture. The planktonic form of the isolate was susceptible in vitro to the antibiotics administered to the patient, but the strain was capable of forming biofilms and this phenotype showed resistance to high concentrations of the same antibiotics. Conclusions: The presence of a slime-producing strain of S. epidermidis should be considered in endophthalmitis that is unresponsive to specific antibiotic therapy, especially in cases in which an intra-ocular foreign body (e.g., a suture) is present.