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870 Impact of Major Infection (MI) due to Staphylococcus aureus following Cardiac Surgery

Sunday, March 21, 2010
Grand Hall (Hyatt Regency Atlanta)
Luke F. Chen, MBBS, FRACP , Duke University Medical Center, Durham, NC
Jean M. Arduino, ScD , Merck, North Wales, PA
Shubin Sheng , Duke Clinical Research Institute, Durham, NC
In-Gyu Bae, MD , Gyeonsang National University School of Medicine, Jinju, South Korea
Lawrence H. Muhlbaier, PhD , Duke Clinical Research Institute, Durham, NC
Zeina Kanafani, MD , American University of Beirut Medical Center, Beirut, OC, LEBANON
G. Ralph Corey, MD , Duke Clinical Research Institute, Durham, NC
Vance G. Fowler Jr., MD, MHS , Duke University Medical Center, Durham, NC

Background:

MI is a serious complication of cardiac surgery. The epidemiology and outcome of MI following cardiac surgery remain poorly understood. We hypothesize that S. aureus remains as the predominant pathogen for MI following cardiac surgery and such complications are associated with poor outcomes including an excess in mortality.

 

Objective:

To describe the epidemiology, microbiology, and outcome of patients with MI following cardiac surgery.  

 

Methods:

We evaluated prospectively-collected data from the Society of Thoracic Surgeon (STS) National Cardiac Database from propensity-score matched patients with and without MI. Subjects were enrolled from 5 sites who underwent cardiac surgery between January 1, 2000 and December 31, 2004. Case records with missing data on age, gender and infection status were excluded. Outcomes of interest were MI, (defined as microbiologically-documented bloodstream or chest wound infection), and mortality within 30 days of surgery.  Multivariable logistic regression models were constructed with backward selection to determine risk factors for mortality. Final multivariable models included the following variables: propensity score, MI associated with specific pathogens.

 

Results:

Of 10,522 patients analyzed, 341 patients developed MI (overall rate of MI: 3.2 per 100 procedures). The rate of MI decreased from 5.4 per 100 procedures in 2000 to 2.6 per 100 procedures by the end of 2004 (p<0.001).  Risk factors for MI included: BMI ≥ 40 kg/m2, emergent surgical procedure, immunosuppressed state and having co-morbidities such as diabetes, renal impairment, or a history of peripheral or cerebrovascular disease. 30 day mortality (8.5% vs. 2.2%; p< 0.001) and median post-operative hospitalization (15 vs. 6 days; p<0.001) was significantly higher in patients who developed MI. 

While gram-negative bacteria, as a group, were found in 27% of MI, S. aureus alone accounted for 26% of MI. Furthermore, patients with MI associated with S. aureus were at a higher risk of 30 day mortality than uninfected individuals (aOR: 3.0; 95% CI:  1.45-6.30), and patients with MI caused by coagulase-negative staphylococci (aOR: 3.46; 95% CI: 1.01-11.9).

 

Conclusions:

S. aureus is a leading pathogen of MI following cardiac surgery. The outcome for patients with MI due to S. aureus was substantially worse compared to patients with MI caused by other pathogens or uninfected individuals.