The knowledge of the expected time-to-positivity (TTP) of blood cultures by major pathogens is essential both clinically and economically. To this end, we conducted the present two‑year study in our Institution, aiming to assess the TTP of all the major microorganisms including Enterobacteriaceae, Pseudomonas aeruginosa, Acinetoacter baumannii, Enterococcii spp, Staphylococcus aureus and yeasts, to determine whether a 3‑day interval is sufficient for their detection. The TTP for each case of strain isolation per patient was determined as the TTP of the first bottle among a set of bottles collected within the same period of time to be flagged as positive per patient. Based on our results, almost all major Gram‑negative (99.30%), Gram‑positive microbia (99.01%) and yeasts (98.85%) were detected within the first 5‑days of incubation, leading to the solid conclusion that a 5‑day period of incubation is adequate to detect almost all the major routine pathogens. By contrast, when a 3‑day period was examined acceptable results were only found for Gram‑negative (98.33%) and Gram‑positive (98.51%) microbia. A significant proportion of yeasts (8.05%) could not be detected within this time frame. Therefore, regarding the yeasts, a 3-day incubation period cannot be considered as adequate and is not advocated.

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