Sequential time to positivity of blood cultures can be a predictor of prognosis of patients with persistent Staphylococcus aureus bacteraemia

Abstract

A short time to positivity (TTP) correlates with poor clinical outcome in patients with Staphylococcus aureus bacteraemia, but the association between sequential TTPs and the outcome of these patients is unclear. Sequential TTPs from patients with S. aureus bacteraemia persisting for >48 h were analysed with respect to clinical parameters and patient outcome at a tertiary hospital. During the 5-year study period, 87 patients (9.2%; mean age of 64 years) had persistent S. aureus bacteraemia, with an average Pittsburgh bacteraemia score of 2.7. Forty-eight patients (55%) had methicillin-resistant S. aureus infection, and 28 (32%) had nosocomial infection. The most common underlying disease was end-stage renal disease (43%). The most common type of infection was catheter-related infection (31%), followed by infective endocarditis (18%). The in-hospital mortality rate was 40%. Higher Pittsburgh scores (p 0.005; OR 1.37; 95% CI 1.1-1.7) and a second TTP/first TTP ratio of <1.5 (p 0.004; OR 0.2; 95% CI 0.07-0.6) were independent risk factors for mortality. Among patients receiving adequate empirical therapy, a second positive blood culture growing within 12 h was more frequent in patients who finally died. Factors associated with a second TTP/first TTP ratio of <1.5 included older age (p 0.02; OR 0.96; 95% CI 0.92-0.99) and inadequate empirical antimicrobial therapy (p 0.01; OR 3.53; 95% CI 1.42-8.78). Among patients with persistent S. aureus bacteraemia, a second TTP/first TTP ratio of <1.5 is a predictor of poor outcome. Physicians should search for interventions guaranteeing that all patients with S. aureus bacteraemia receive adequate empirical therapy.

High nuc DNA load in whole blood is associated with sepsis, mortality and immune dysregulation in Staphylococcus aureus bacteraemia

“…Previous studies have shown that a short time to positivity is associated to poor clinical outcome in S. aureus bacteraemia [31,32]. It has also been suggested that in patients with persistent S. aureus bacteraemia a sustained short time to positivity in the follow-up blood culture can be a marker for mortality risk [33,34]. In addition, persistence of bacterial DNA in blood (using the multiplex PCR-test SeptiFast) has been associated to endovascular complications in S. aureus bacteraemia [35].…”

Blood culture time-to-positivity: making use of the hidden information

“…This important exception reflects that TTP from S. aureus bacteraemia is complex and presents atypical characteristics. Fourth, TTP is probably useful in monitoring patients treated for S. aureus bacteraemia, as failure to increase TTP by at least 50% in sequential blood culture was more frequently associated with a new focus on infection and death [15], suggesting that more aggressive treatment should be prompted with such TTPs. Fifth, TTP was advocated for distinguishing between methicillin-resistant and methicillin-susceptible S. aureus, but the literature presents conflicting data [7,10].…”

What role does the quorum-sensing accessory gene regulator system play during Staphylococcus aureus bacteremia?

“…Disseminated infection foci can be difficult to identify and failure to eradicate them is associated with persistent bacteremia and poor outcomes [3,4]. In turn, the likelihood of dissemination is related to the duration of bacteremia, underscoring the importance of the rapid application of appropriate therapeutics [1,3,5]. Unsurprisingly, antibiotic resistance poses a significant therapeutic challenge and bacteremia caused by methicillin-resistant S. aureus (MRSA) is strongly associated with persistent bacteremia and carries a higher mortality rate than that caused by sensitive isolates [3,4,6].…”