title: Risk factors for postoperative chest wound infections due to gram-negative bacteria in cardiac surgery patients.
abstract: Gram-negative bacteria account for up to 35% of postoperative sternal wound infections (SWI) in patients undergoing cardiac surgery. Despite this, risk factors for Gram-negative SWI have not been investigated. The objective of this study was to define risk factors associated with Gram-negative SWI in patients undergoing cardiac surgery. 2590 patients undergoing cardiac surgery between 2002-2005 were prospectively monitored for development of SWI. Patient, operative, and post-operative risk factors were compared among patients that developed Gram-negative SWI and Gram-positive SWI to uninfected controls using univariate and multivariate analysis. A p < 0.05 was considered significant. Surgical site infections developed in 152 (5.9%) patients. Isolates were recovered from the sternum for 128 (5.0%) patients, from the leg donor site for 19 (0.73%) patients, and from the sternum and donor site for 5 (0.19%) patients. Gram-positive pathogens were isolated from 83 (3.3%) patients, Gram-negative pathogens from 42 (1.6%) patients, and mixed pathogens from 27 (1.0%) patients. Hospital admission greater than 48 hours before surgery (OR: 2.25; 95% CI: 1.11 - 4.58), ventilator-dependency preoperatively (OR: 5.32 95% CI: 2.22 - 12.75), and thoracentesis procedure postoperatively (OR: 3.71; 95% CI: 1.45 - 9.49) and diabetes (OR: 2.04; 95% CI: 1.17 - 3.55) were identified as significant risk factors for SWI due to Gram-negative bacteria using multivariate logistic regression. Diabetes, increased age, and peripheral vascular disease were identified as significant risk factors for SWI due to Gram-positive bacteria (p < 0.05, each). The risk factors associated with Gram-negative SWI differed significantly from those associated with Gram-positive SWI. Risk factors associated with Gram-negative SWI were identified. Unique interventions may be necessary to prevent Gram-negative SWI in cardiac surgery patients.
authors.affiliation: University of Houston, 1441 Moursund Street, Houston, TX 77030, USA. kgarey@uh.edu
authors.forename: K W
authors.initials: KW
authors.lastname: Garey
authors.forename: N
authors.initials: N
authors.lastname: Kumar
authors.forename: T
authors.initials: T
authors.lastname: Dao
authors.forename: V H
authors.initials: VH
authors.lastname: Tam
authors.forename: L O
authors.initials: LO
authors.lastname: Gentry
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures; D016022:Case-Control Studies; D001026:Coronary Artery Bypass; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology / Q000517:prevention & control*; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D017053:Infection Control; D008297:Male; D015999:Multivariate Analysis; D011446:Prospective Studies; D012307:Risk Factors; D013249:Sternum; D013530:Surgical Wound Infection / Q000453:epidemiology / Q000517:prevention & control*; D013781:Texas / Q000453:epidemiology