Clinical Comparative Study of Quantitative Lysis Filtration and Lysis Centrifugation Blood Culture Techniques for Streptococcus Bacteremia

It has been suggested that transient bacteremia following oral procedures may cause infective endocarditis in susceptible patients and streptococci remain the most common pathogenic bacteria for infective endocarditis. Blood samples of 20 patients after tooth extraction were cultured by two different quantitative blood culture techniques; lysis filtration and lysis centrifugation (Isolater 10). Both techniques are performed by first lysing the blood cells, then followed by filtration or centrifugation. Isolated rates were compared by recovery of oral streptococci. The incidence of streptococcis bacteremia were 60% by lysis filtration and 5% by isolater 10. The concentration of oral streptococci in positive blood samples by lysis filtration ranged from 0.12 to 3.72 CFU/ml (mean, 0.62).Streptococcus constellatus andGemella morbillorum were isolated by both techniques in patient 1, the concentration was 3.72 CFU/ml by lysis filtration but only 0.2 CFU/ml by isolater 10.s. constellatus was the most common isolate. Also isolated wereS. intermedius, S. sanguis, S. mutans andG. morbillorum. Polymicrobial streptococcus bacteremia was found in 4 patients. A combination ofS. constellatus andG. morbillorum was isolated from three patients. In conclusion, lysis filtration was an excellent quantitative blood culture technique for the isolation of streptococci. Lysis filtration should provide a better comparison of the efficacy of different antibiotics used in the prevention of transient dental bacteremia.