It is reasonable that the counting of days for the duration of antimicrobial therapy begin on the first day on which blood cultures are negative in cases in which blood cultures were initially positive (Class IIa; Level of Evidence C). 3. It is reasonable to obtain at least 2 sets of blood cul- tures every 24 to 48 hours until bloodstream infec- tion has cleared (Class IIa; Level of Evidence C). 4. If operative tissue cultures are positive, then an entire antimicrobial course is reasonable after valve surgery (Class IIa; Level of Evidence B). 5. If operative tissue cultures are negative, it may be reasonable to count the number of days of anti- microbial therapy administered before surgery in the overall duration of therapy (Class IIb; Level of Evidence C). 6. It is reasonable to time the administration of antimi- crobial therapy at the same time or temporally close together for regimens that include >1 antimicrobial agent (Class IIa; Level of Evidence C). Dog or cat exposure Bartonella sp Pasteurella sp Capnocytophaga sp Contact with contaminated milk or infected farm animals Brucella sp Coxiella burnetii Erysipelothrix sp Homeless, body lice Bartonella sp AIDS Salmonella sp S pneumoniae S aureus Pneumonia, meningitis S pneumoniae Solid organ transplantation S aureus Aspergillus fumigatus Enterococcus sp Candida sp Gastrointestinal lesions S gallolyticus (bovis) Enterococcus sp Clostridium septicum HACEK indicates Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species; IDU, injection drug use; and VGS, viridans group streptococci. Table 6. 