Ann Thorac Surg 2000;69:1109
© 2000 The Society of Thoracic Surgeons
ORIGINAL ARTICLES: CARDIOVASCULAR
Invited commentary
Sherif B. Mossad, MDa
a Department of Infectious Diseases, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA
e-mail: mossads{at}ccf.org
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Introduction
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 Introduction
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Surgical site infection after cardiac operation is a major cause of morbidity and potential mortality. Numerous studies were done to elucidate the microbiology, risk factors, and management of this complication. Tegnell and colleagues concentrated their observation on deep sternal wound infections (SWI) caused by coagulase-negative staphylococci (CoNS). They nicely outlined the clinical presentation and potential risk factors for this type of infection. Other organisms that should be included in the differential diagnosis of indolent, late onset SWI include enterococcus, propionibacterium acnes, mycoplasma hominis, legionella pneumophila, mycobacteria other than tuberculosis, and candida species. The minor symptoms mentioned by the authors should always be taken seriously in order to avoid further complications of this infection. I entirely agree that CoNS should never be discarded as a contaminant when clinical evidence for wound infection is present.
The reason why they found a much higher proportion of deep SWI and recurrent infections due to CoNS than what was found in prior studies is unclear. Previous studies found that most SWI due to CoNS are classified as superficial, an entity not included in this review. However, blood stream infections are seen in 14% of SWI due to CoNS. This urges us to consider all SWI due to this organism as serious as other more virulent organisms, particularly in the setting of prosthetic valvular replacement. This organism is known for its adherence to prosthetic materials by hydrophobic interactions and formation of a glycocalyx or slime substance that protects bacteria from antibiotics and host defense mechanisms.
The risk factors they studied are certainly among the most important studied in the literature. Several other risk factors are worth discussing including breast size in females, glycemic control in diabetics before and after surgery, use of internal mammary arteries for CABG, and period of mechanical ventilation postoperatively. All patients in this study underwent cardiac operation through a median sternotomy and one would wonder if the rate of infection would have been different had minimally invasive or endoscopic approaches been used.
I suspect that if the costs of intravenous antibiotics and nursing care after discharge from the hospital were factored in, a larger cost difference may have been found in patients with SWI.
Related Article
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Coagulase-negative staphylococci and sternal infections after cardiac operation
- Anders Tegnell, Claes Arén, and Lena Öhman
Ann. Thorac. Surg. 2000 69: 1104-1109.
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