> I read the 'Manual of Clinical Microbiology', published by ASM, a while ago,
> but I seem to remember that coagulase negative Staphs can take even weeks to
> grow particularly from prosthetic heart valves. We sign out our negative
> cultures in 3 days but hold the broth cultures for 7 days, screening them daily
> for growth before we discard them. We hold blood cultures for 5 days before
> reporting them as negative. For more information, I suggest you read the
> chapter on Staph in the 'Manual of Clinical Microbiology'.
We culture blood for 7 days, except in case of endocarditis, then we culture for 3
Not only for CNS, but also very low numbers of streptococci, Propionibacterium and
fastidious gramnegatives can be cultured that way. It is important then that many
blood cultures are taken. Not only to rule out contamination.
Our problem is that our bloodculture machine (Vital) can only be programmed for 10
days max. So after those 10 days we have to make subcultures weekly. I'll be glad
when we can throw that machine out of the window ......