Prosthetic heart valve endocarditis caused by Bacillus circulans.

We report a case of prosthetic valve endocarditis due to Bacillus circulans in a 56-year-old woman. Pre-operative blood cultures were negative and the organism was only recovered on culture of the explanted mechanical valve. We discuss the reasons for the late clinical presentation of this case, 15 months post valve replacement, caused by an organism which is conventionally regarded as 'early' pathogen. The patient recovered well post surgery on a 6 week course of trimethoprim and ciprofloxacin.