Hospital-Onset S Aureus Bacteremia Associated With Twice the Mortality as Community-Onset

Staphylococcus aureus infections can lead to sepsis and bacteremia, which are associated with considerable mortality rates despite available antimicrobial therapy.

Patients who present to the hospital with S aureus bacteremia (SAB) also have a high risk of complications. Therefore, an assessment of both community-onset SAB and hospital-onset SAB is needed.

In a new study presented in a poster session at IDWeek 2019, a team of investigators sought to examine outcome measures for patients with hospital-onset SAB. At the conference, Contagion® spoke to poster presenter Florian Daragjati, PharmD, director of antimicrobial stewardship in the Department of Clinical Investigation at Ascension.

The team used a clinical support system to identify 2700 patients with the presence of at least 1 positive blood culture for S aureus from April 2018 to March 2019 in a single health system comprised of 58 hospitals. The patients were then matched in the US Premier Healthcare database to obtain outcome measures for mortality, rate of complications, length-of-stay and cost of treatment. Outcome measures were compared overall and between community-onset (identified in the first 3 days of admission) and hospital-onset (identified on the fourth day after admission).

The poster reports that baseline characteristics were similar between the 2 groups. Community-onset cases accounted for 2413 (89.4%) of the overall cases, while 287 (10.6%) of the cases were hospital-onset.

The study found that for overall SAB, the mortality rate was 11.9%, the complication rate was 35%, observed length of stay was 11.97 days, and mean observed cost per admission was $29,114. However, the team overserved a statistically significant higher observed mortality rate (14.8%, 95% CI [Confidence Interval], 9.61, 19.93), complications rate (53.3%), length of stay, (11.06 days), and cost per admission ($33,285) for hospital-onset SAB compared to community onset.

According to the investigators, these findings indicate that SAB continues to be an important source of morbidity and mortality for hospitalized patients. While hospital-onset SAB accounted for about 1 in 10 cases, it is associated with 182% higher complication rate and 144% higher mortality than community-onset infections.

“Incorporating best practices into the management of SAB and hardwiring prevention strategies to mitigate SAB risk should be considered by US hospitals,” the authors wrote.

However, the study data show a lower mortality rate for overall SAB (11.9% vs 18%), community-onset SAB (10.3% vs 18%) and hospital-onset SAB (25.1% vs 29%) compared to recent national data.

According to the investigators, the health system in this study developed guidelines in the acute care environment that incorporate several proven bundle elements that can result in improvement in outcomes of SAB. These bundle elements include infectious consult, prompt source control, follow-up blood cultures until clearing, appropriate echocardiography, appropriate and timely antimicrobial therapy with duration based on complications, and a clearly outlined discharge plan.

“Hospital-onset SAB is associated with more than twice the mortality, complication rate, length of stay, and cost compared to community-onset SAB,” the authors conclude. “Structured efforts to reduce the risk for hospital-onset SAB and optimize the management of SAB are essential to improve patient outcomes.”

Daragjati also explained the guidelines that were implemented and discusses his biggest takeaways.

The abstract, Hospital-Onset Staphylococcus aureus Bacteremia is Associated with more than Twice the Mortality Compared to Community-Onset: Evaluation of 58 Hospitals, was presented in a poster presentation on Thursday, October 3, 2019, at IDWeek 2019 in Washington DC.