Rickettsial endocarditis

A comparison of Q fever endocarditis with native valve endocarditis

We compared 10 episodes (8 patients) of Q fever endocarditis with 27 episodes (27 patients) of native valve endocarditis. Patients with Q fever endocarditis were more likely to have weight loss (p less than 0.003), experience fatigue (p less than 0.07), have clubbing of the fingers (p less than 0.005), have a diastolic murmur at the time of admission (p less than 0.03), be anemic (p less than 0.05), have a normal white blood cell count (p less than 0.005), and have a higher serum globulin concentration (p less than 0.007). While valve replacement was required for 50% of the episodes in both groups of patients, it was required later--mean 107 days following the onset of treatment--for the Q fever patients than for the native valve patients--mean 27 days. The mortality rates for these two diseases were not significantly different (30% for native endocarditis vs. 12.5% for Q fever endocarditis), but the Q fever patients experienced significantly fewer complications.

Q fever endocarditis

Q fever endocarditis is described in a man aged 48 years, known to have had a rheumatic fever-like illness in 1960. He had evidence of aortic valve disease when seen with mumps infection in 1963. He was again seen in 1966 with suspected subacute bacterial endocarditis, but later, Q fever infection was shown to be present by serological tests. He survived for just over one year from the presumed onset of Q fever, in spite of prolonged intensive antibiotic therapy.

Necropsy examination showed chronic congestive cardiac failure with pleural and pericardial effusions, and calcific aortic stenosis with tiny vegetations along the edges of the cusps. Rickettsia burneti was isolated only from the damaged aortic valve, and histology revealed colonies of cocco-bacillary bodies between the collagen bundles. Immuno-fluorescence studies suggested that the rickettsiae were heavily coated with 7S gamma globulin (presumably the patient's own specific antibody).

It is important to consider Q fever endocarditis in all cases presenting as bacterial endocarditis.