All Blood Cultures Are Always Positive

摘要

The aim of present work is to describe a method used to prove that all blood cultures are always positive because human blood has normal flora. There are negative blood cultures on account of sodium polyanethol sulfonate (SPS) bacteriostatic properties on Chlamydia-like microorganisms living as normal flora in human blood. Introduction SPS is an anticoagulant with surface-active action. It is used worldwide in blood culture media, because of believe that it makes number of positive blood cultures to increase, and accelerates obtainment of results (1). It is very important that SPS inhibit phagocytosis and in this way helps microorganisms in blood to survive (2). There is literature data however that SPS can be toxic for some microorganisms (3).The finding that in the blood off every man or woman live Chlamydia-like microorganisms as normal flora (4,5,6,7) means that all blood cultures must be always positive, in contradiction with the routine practice in which some blood cultures are evaluated as positive ones, and others as negative ones Methods BACTEC blood culture (8,9) assessed as negative, are lived in repose for 24 hours. Very carefully the medium is poured out avoiding shaking of blood. Decantation of medium stops when deposited on the bottom blood begins to pour out. 0, 5 ml of resting blood sediment is cultured in a tube with 4, 5 ml brain heart infusion with: 0, 25% sodium citrate, gentamicin 20 mg/l and chloramphenicol 50 mg/l, without SPS. After 30 days incubation at 37°C a Gram stained smear was made / Fig 1 / as well as electron microscopy photographs/ Fig 2 ,3 4, 5 /