如何理解心内膜炎诊断中的“2次”

2015年ESC制定的感染性心内膜炎微生物诊断标准为：
1. Blood cultures positive for IE
a. Typical microorganisms consistent with IE from 2 separate blood cultures:
• Viridans streptococci, Streptococcus gallolyticus (Streptococcus bovis), HACEK group, Staphylococcus aureus; or
• Community-acquired enterococci, in the absence of a primary focus;
or
b. Microorganisms consistent with IE from persistently positive blood cultures:
• ≥2 positive blood cultures of blood samples drawn >12 h apart; or
• All of 3 or a majority of ≥4 separate cultures of blood (with and last samples drawn ≥1 h apart);
or
c. Single positive blood culture for Coxiella burnetii or phase I IgG
antibody titre >1:800



疑问：诊断中的“2次独立血培养”如何理解？是指同一个时间内抽的双侧血标本还是不同时间点采集的标本？

重复？