" [...] in the 1980’s the first automated system was introduced which used radiolabeled carbon to detect CO2 production resulting from organism growth. This reduced labor required and allowed for automated monitoring, but direct sampling was still necessary, [ ... ]
Time to Positivity
When the instrument detects growth [see 'CO2 production' above], it records the time between the bottle’s start of incubation and end time, termed the TIME TO POSITIVITY. Time to positivity is ideally reported as days and hours to provide maximal information to the clinician.
https://asm.org/Articles/2018/November/Predictive-Value-of-B...

"Time to positivity (TTP) in blood cultures indicates the time from the beginning of culture incubation to the detection of bacterial growth by the automated system. Shorter TTP may reflect a higher bacterial concentration in blood, which in turn may be associated with severe infection"
https://academic.oup.com/ofid/article/9/6/ofac163/6562892

Potentially, then, your "0,0" would be 0 days, 0 hours. That is to say, since the result was negative, no value pertaining to positivity was entered.



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Note added at 7 hrs (2023-01-09 00:09:10 GMT)
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I've not found any examples of the 'days, hours' notation referred to above. Most of the values I've found are less than 24 hours.

Time to positive detection (TTP) in DECIMAL HOURS for three sets of simulated blood cultures prepared using three dilutions of the same broth culture of B. anthracis
https://pure.port.ac.uk/ws/portalfiles/portal/5568694/SHAWKE...

TTP from anaerobic bottles (MEAN OF 15.6 HOURS, RANGE 11–26 HOURS) was significantly faster than TTP from aerobic bottles (mean of 49.5 hours, range 13–100 hours) (P

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Note added at 7 hrs (2023-01-09 00:12:20 GMT)
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So maybe your 0,0 is 0,0 heures, requiring a decimal marker change to become '0.0' (hours). For all the difference it makes ...