SYNOPSIS Pre-and post-extraction blood cultures were taken from 242 patients. The post-extraction ones were taken from 100 unpremedicated patients, from 42 with an erythromycin estolate cover, and from 100 patients after protection with pyrrolidino methyl tetracycline. The 100 post-extraction blood cultures from unpremedicated patienits gave 64 positive results which yielded 155 strains, 88 of which were not aerobes.One hundred and fifteen representative strains were tested for sensitivity to 22 antibiotics. Of the 42 patients who received the erythromycin orally, 16 yielded positive blood cultures of mixtures of aerobes and anaerobes and of the 100 given one intravenous injection of the tetracycline three only developed a bacteraemia of a single type of aerobe. The serum concentrations obtained with the tetracycline given intravenously were 15 to 20 times higher than the serum levels obtained with the erythromycin given orally.There is a strong indication for using this kind of efficient antibiotic cover for dental extractions and other operative procedures known to be followed by a bacteraemia.Bacterial endocarditis is in many cases the result of bacteraemia produced by operative procedures, among which is tooth extraction. It is stated that 25 to 50% of endocarditis patients had one or more teeth extracted some two months before the onset of the valvular ailment (Cates and Christie, 1951). Northrop and Crowley (1943) reported 23 such cases, and 94 other cases are on record by various other authors.The bacteraemia of tooth extraction is transient, lasts about 10 minutes (Northrop and Crowley, 1943; Okell and Elliott, 1935), and the bacteria are most numerous in the blood stream within the first two minutes of their introduction into the circulation (Reichel, 1939). In persons with heart valves damaged by rheumatic fever, syphilis, or a congenital defect, the platelet-and-fibrin thrombi on the surface of the diseased valves trap some of the bacteraemic organisms, which then multiply and start an endocardial vegetation. The circulation time from the site of a tooth socket to an elbow vein is less than 18 seconds (Koch, 1922
56For an antibiotic cover during dental extraction various investigators tried sulphonamide compounds, penicillin, and other antibiotics, but all except one failed to isolate one single anaerobe in their unpremedicated post-extraction control blood cultures. Using sulphanilamide, Pressman and Bender (1944) obtained 7 % reduction (from 83 % to 76%) and Northrop and Crowley (1943) 5*4% reduction (from 15% to 9 6%). With penicillin the reductions varied from 9 % (Hirsch, Viveno, Merril, and Dowling, 1948) to 42 % (Schirger, Martin, Royer, and Needham, 1960). With antibiotics other than penicillin the reductions were 61 % (Khairat: the present work, the highest reduction ever obtained, in a series of 100 patients with 88 anaerobes isolated), 44 % (Roth, Cavallaro, Parrott, and Celentano, 1950) with aureomycin orally, 280% (Bender, Pressman, and Tashman, 1958) using streptomycin sulphate intra...