Rational approaches to the treatment of culture-negative infective endocarditis

Infective endocarditis: a five-year experience at a tertiary care hospital in Pakistan

OBJECTIVES

Infective endocarditis is common and data regarding its pattern and outcome from developing countries is sparse. We therefore examined the spectrum, demographics and clinical features of infective endocarditis and sought to determine the factors affecting its clinical outcome.

PATIENTS AND METHODS

Over a five-year period at our university hospital in Karachi, Pakistan, we identified 66 patients with infective endocarditis and compared their clinicoepidemiologic features and outcomes to subjects in the West.

RESULTS

The male:female ratio was 2:1; overall median age was 24 years (35.5 years for men and 13.5 years for women) (p < 0.001). Median duration of symptoms before presentation was 20.5 days. Major predisposing cardiac abnormalities included congenital (50%) and rheumatic (23%) lesions, and a history of heart surgery (17%). Causative organisms and valvular sites of infection were similar to those seen in developed countries. Blood culture-negative infective endocarditis was found in 48% of cases. Renal failure was more frequent among culture-positive patients (p = 0.055). Risk factors for mortality included neurologic (p = 0.003) and embolic (p = 0.02) complications, renal (p = 0.03) and left ventricular failure (p = 0.002), and a history of cardiac surgery (p = 0.026). Overall mortality was 27%.

CONCLUSIONS

Patients with infective endocarditis in Pakistan exhibit significant differences compared to their counterparts in the West, including younger age at presentation, incidence of predisposing cardiac conditions, and gender differences reflecting sociocultural bias. Neurologic and embolic complications, renal failure and heart failure predict a worse outcome.

Conventional viral cultures and shell vial assay for diagnosis of apparently culture-negative Coxiella burnetii endocarditis

A patient with culture-negative endocarditis was diagnosed with Q fever endocarditis based on the results of serological tests and positive leukocyte cultures obtained using conventional viral cultures and the shell vial technique. This case report suggests that isolation of Coxiella burnetii from blood may allow better diagnostic and therapeutical evaluation of patients with Q fever endocarditis. The use of both conventional and shell vial viral cultures is recommended for the isolation of Coxiella burnetii from the blood of patients with apparently culture-negative endocarditis.

IgG antibody response in bacterial endocarditis using ELISA with multiple antigens

By means of enzyme-linked immunosorbent assays (ELISAs) the antibody responses were detected in sera from normal persons (n = 275), patients with various types of bacteremia (n = 137), and patients with endocarditis (n = 28). Four ELISAs were evaluated. As antigens ultrasonic extracts of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and nonhemolytic streptococci were used. The antibody levels against S. aureus increased with age, while antibodies against the other bacteria showed no age variation. The different ELISA systems showed many serological cross-reactions. The ELISA in this limited material was 72% successful in identifying cases of bacterial endocarditis caused by S. aureus (diagnostic sensitivity 84%; diagnostic specificity 89%), while in other cases of bacterial endocarditis it was less successful.