Blood Stream Infection in Patients Undergoing Systematic Off-Pump Coronary Artery Bypass: Incidence, Risk Factors, Outcome, and Associated Pathogens

Background:
Blood stream infection (BSI) is a major cause of mortality and morbidity for patients undergoing cardiac surgery.
However, information is lacking about patients undergoing off-pump
coronary artery bypass (OPCAB). The purpose of this study was to assess
the incidence, risk factors, outcome and associated pathogens of BSI
after OPCAB.

Methods:
One thousand ten consecutive patients undergoing
OPCAB between 2001 and 2012 were included in a retrospective
case-control study. A propensity-matched control was used for risk
factor analysis.

Results:
Of the 1,010 patients, 26 patients (2.6%) had
32 episodes of BSI after surgery, which occurred at a median of 14 d after surgery.
Gram-negative bacilli and gram-positive cocci were distributed equally.
Methicillin-resistant Staphylococcus aureus was the pathogen identified
most frequently, and the most common source of infection was a surgical
site. The hospital mortality rate was 54%. By univariable analysis,
diabetes mellitus, pre-operative renal impairment, pre-operative low
hemoglobin, pre-operative endotracheal intubation, dialysis before or
after surgery, cardiogenic shock, left ventricular ejection fraction of less than 40%, non-elective surgery, low number of distal anastomoses, atrial fibrillation after surgery,
and re-operation for bleeding were significant risk factors. By
multivariable analysis, the independent risk factors were left
ventricular ejection fraction of less than 40%, low number of distal
anastomoses, atrial fibrillation after surgery, and dialysis after surgery.

Conclusions:
Blood stream infections remained a common complication
after OPCAB, and the mortality was high. Gram-negative bacilli and
gram-positive cocci were distributed equally. Methicillin-resistant S.
aureus was the pathogen identified most frequently. Preventive tactics
should target likely pathogens and high-risk patients undergoing OPCAB.