Moraxella species are a group of gram-negative, oxidase- and catalase-positive coccobacilli. These organisms usually do not grow on MacConkey agar, and the nitrate test is negative. Moraxella species may cause eye infections including conjunctivitis, endophthalmitis, and corneal ulcers.
We report a case of native mitral valve endocarditis caused by Moraxella nonliquefaciens in a patient with a history of rheumatoid arthritis. She developed embolic complications on the third week of antimicrobial therapy. Transesophageal echocardiogram showed severe mitral regurgitation and perforation of valvular leaflets. The patient underwent successful mitral valve replacement with recovery of motor functions.
This case illustrates that M. nonliquefaciens can be complicated with embolic phenomena and that early surgical intervention may be useful in selected patients to prevent embolic complications and disability. To our knowledge, this is the first reported case of native valve endocarditis caused by this organism.