Bacteraemia in asymptomatic human subjects

Abstract

The common occurrence of post-tooth extraction bacteraemia provides a convenient model system to evaluate techniques which demonstrate the magnitude of the bacteraemia. The system used continuous anaerobiosis and membrane filter recovery to quantitate bacteraemia. 19 of 22 pre-extraction blood samples and 20 of 22 post-extraction samples from hospitalized patients had one or more colonies per 5 ml of blood. Colonies recovered averaged 7.3 per 5 ml of blood for the pre-extraction samples and 10.7 for the post-extraction samples. 86 per cent of the pre-extraction bloods contained bacteria. 30 of 42 pre-extraction and 32 of 41 post-extraction samples from asymptomatic patients having teeth extracted had a bacteraemia which averaged about 5 colonies per 5 ml of blood. Subsequent studies were concerned with the prevalance of detectable bacteraemia. In one series of presumably healthy blood bank donors, blood from 16 of 20 donors was positive for bacteria, with an average recovery of 11 organisms per 5 ml of blood. In a second series, in which multiple samples were tested, 18 of 29 donors were positive with an average recovery of 2 organisms per 5 ml of blood. The taxonomic characteristics of the isolates suggested that they could have originated from the intestine (Streptococcus faecalis), the skin (Propionibacterium acnes and Staphylococcus epidermidis) and the oral cavity (Actinomyces viscosus).