Paracoccus yeei, a Rare Cause of Ocular Infection

Abstract

Abstract Objectives Paracocci are nonfermenting obligate aerobes. The genus Paracoccus is classified in the family Rhodobacteraceae and contains 31 species. Gram stains reveal gram-negative cocci, diplococci, or coccobacilli/short rods, sometimes described as having an O shape due to peripheral stain. It may be confused with Neisseria sp. or Moraxella sp. due to oxidase positivity. Paracoccus yeei, a rare cause of infection in patients ranging from 6 weeks to 77 years, has been isolated from abdominal dialysate, wounds (ankle, toe), incision drainage, cerebrospinal fluid, bile, skin, blood, ear, and eye (uveitis, conjunctivitis, corneal transplant graft infection). It is a rare emerging pathogen with low pathogenic potential. Methods A 65-year-old heroin-dependent male with a nonfunctional left eye due to gasoline injury presented with a traumatic injury to the right eye. The ophthalmological exam revealed a central corneal ulcer, hazy pupil, right upper and lower lid swelling, periorbital edema with central vision loss, and conjunctival chemosis. B-scan showed no vitreous debris. Cultures of the ulcer were taken, and fortified tobramycin and fortified vancomycin drops were started. Results Nonhemolytic, whitish-gray, convex colonies, measuring 0.5 to 1 mm in diameter, grew on Columbia sheep blood and chocolate agar plates at 48 hours. Tiny pinpoint colonies were identified on MacConkey agar plate at 3 days. Gram stain revealed a small short gram-negative rod, which was oxidase and catalase positive. Microscan identified the isolate as P yeei. Antibiotic susceptibilities revealed low MICs for beta-lactam antibiotics and higher MICs for cephalosporins. The ulcer healed very well. The patient’s vision improved. The patient was subsequently discharged with instructions to follow up with clinic. Conclusion Our case reinforces the need to consider uncommon pathogens, including P yeei in eye infections and the role of microbiology in correctly identifying the organism where delay or incorrect treatment can lead to permanent damage.