HACEK GROUP ENDOCARDITIS AT THE RIYADH ARMED-FORCES HOSPITAL

Introduction: Fastidious Gram-negative organisms classified as the HAC EK group (Haemophilus spp., Actinobacillus actinomycetemecomitans, Car diobacterium hominis, Eikenella corrodens and Kingella spp.) are rare causes of infective endocarditis. Case report: In this series, we repo rt six cases of endocarditis in Saudi patients occurring between 1990 and 1994 in our hospital, caused by two of the organisms in the HACEK group, i.e. Cardiobacterium hominis and Actinobacillus actinomycetemco mitans. The clinical features, predisposing factors and treatment of t he patients are briefly described. The microscopic and cultural charac teristics of the organisms are described together with the laboratory methods of diagnosis. Major findings: HACEK endocarditis was frequentl y associated with prosthetic heart valves or structural heart abnormal ities. Dental caries or periodontal disease seems to be a predisposing factor. The prognosis of HACEK endocarditis is very good as clinical and bacteriological cure were achieved with antibiotic therapy in all our cases except one who required mitral valve replacement. Contrary t o previous reports we did not find all the organisms sensitive to peni cillin and aminoglycosides. However, all our isolates were sensitive t o amoxycillin, cefuroxime, ceftriaxone and ciprofloxacin. Conclusions: Laboratory diagnosis of HACEK group of organisms requires a high inde x of suspicion and should be suspected in cases of endocarditis in whi ch fastidious Gram-negative coccobacilli are isolated which fail to gr ow on MacConkey agar. Empiric therapy should be started in suspected c ases with second generation cephalosporins or wit ciprofloxacin, until antibiotic sensitivity results become available. Antibiotic therapy s hould be continued for 4-6 weeks. Progress and outcome was very good i n the series.