<qa>  What is the time to positivity of a blood culture bottle recorded in the microbiology1. Patients with probable or definite diagnosis of uncomplicated gram positive bacteremia that have at least one positive blood culture including 20 patients with Staphylococcus aureus and the other 20 patients will include any of the following organism CNS, Enterococci, streptococci, pneumococci, Corynebacterium, and Propionibacterium or Bacillus species.If the positive blood culture involves a commensal skin organism such as CNS, Corynebacterium, Propionibacterium, Micrococcus and Bacillus, then at least 100 coloniesml will be required or a time to positivity 16 hours as it has been shown to reflect a high grade bacteremia, or two positive blood cultures. Time to positivity of a blood culture bottle is recorded in the microbiology laboratory by the automatic culture detector Bactec 9240 and Bactec Plus AerobicF; Becton Dickinson which records culture positivity every 15 min according to changes in fluorescence related to microbial growth. 