Exploring the correlation between time to positivity and positive culture bottle count in Staphylococcus aureus...

The correlations between time to positivity (TTP) in blood cultures, the number of positive bottles, and their associations with mortality rates and metastatic lesion formation in Staphylococcus aureus (S. aureus) bacteremia remain unclear. This study aimed to evaluate the impact of these factors on the severity, mortality, and frequency of metastatic lesions.

We retrospectively analyzed patients with S. aureus bacteremia who were admitted to our facility.

A total of 317 patients were included in this study, with an average age of 70.3 years (standard deviation [SD]: 17.0); 62.5 % were male, and 22.4 % of cases involved methicillin-resistant Staphylococcus aureus infections. The average TTP was 19.9 h (SD: 11.9). No significant differences were observed in mortality or severity with respect to TTP or number of positive bottles. Further investigation into the relationship with metastatic lesions revealed that the TTP for patients with intravascular infections was significantly shorter, averaging 16.81 h (SD: 5.68), compared to 23.45 h (SD: 13.84) in patients with bacteremia. The TTP for bone and joint infections was significantly shorter, averaging 17.88 h (SD: 8.26). A weak correlation was observed between TTP and the number of metastatic lesions (r = 0.203). Additionally, a weak correlation was found between TTP and the number of positive bottles (r = 0.544).

TTP and bottle count did not predict the severity or mortality of S. aureus bacteremia in our study. However, positivity with a shorter TTP, particularly around or below 20 h, warrants further evaluation for intravascular and bone infections.