Time to Blood Culture Positivity Predicts Pneumonia Severity and Outcome

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A TTP of blood culture <9.2 hours  is independently associated with more severe bacteremic pneumococcal pneumonia.
A TTP of blood culture <9.2 hours is independently associated with more severe bacteremic pneumococcal pneumonia.

The time to positivity of blood culture (TTP) showed that early TTP (<9.2 hours) in patients with bacteremic pneumococcal pneumonia (BPP) predicted the risk for invasive mechanical ventilation, longer hospital stay, and mortality, according to a study by Dr Catia Cillóniz of the department of pneumology, Institut Clinic del Tórax, Hospital Clinic of Barcelona, Spain, and colleagues, published in PLoS One.

Analysis of 278 patients with BPP, mean age 62, showed that the first quartile of TTP (9.2) was the best cut-off for identifying 2 groups of patients at risk.

Early TTP (<9.2 hours) was associated with a statistically significant increased risk for requiring invasive mechanical ventilation (18% vs 6%, P =.007), longer hospital stay (12 days vs 8 days, P <.001), higher in-hospital mortality (15% vs 4%, P =.010), and increased 30-day mortality (15% vs 5%, P =.018).

Early TTP was also found to be associated with a more severe pneumonia clinical phenotype, including increased C-reactive protein, decreased oxygenation, and increased pulmonary complications.

Thus, TTP, which is easy to obtain, indicates the severity of pneumococcal pneumonia and is a good predictor of outcomes.

“TTP is an easy to obtain parameter available in all microbiology laboratories that appears to provide useful prognostic information, and should be reported routinely in order to help clinicians to identify patients at risk of worse outcome that could benefit from more aggressive early management,” the researchers concluded.

Reference

Cilloniz C, Ceccato A, de la Calle C, et al. Time to blood culture positivity as a predictor of clinical outcomes and severity in adults with bacteremic pneumococcal pneumonia [published online August 7, 2017].  PLoS One. doi:10.1371/journal.pone.0182436

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