A 53-year-old man developed severe acute systemic illness three weeks after
an upper respiratory tract infection. Serial blood cultures grew Moraxella
catarrhalis. During antibiotic treatment, fever and infectious parameters
disappeared, but severe aortic regurgitation developed, Aortic valve replac
ement was performed, during which extensive destruction of the aortic valve
wa's noted. Endocarditis due to M. catarrhalis is very rare with, to our k
nowledge, only six cases having been reported to date. M. catarrhalis is a
normal commensal of the upper respiratory tract, but in unpredictable circu
mstances can become an important pathogen. Bacteremia due to this organism
therefore requires prompt treatment, as serious organ complications, includ
ing endocarditis, can occur.