An analysis of 400 sternal wound reconstructions at a single institution: Bacterial pathogens vary with time
Jonathan R. Tiao BSE1, Adam S. Levy MD2, Chloe Altchek AB1, Kevin Kuonqui, BA1, Jeffrey A. Ascherman MD2
1Columbia University Vagelos College of Physicians and Surgeons, New York, NY; 2Division of Plastic Surgery, Department of Surgery, Columbia University Irving Medical Center, New York, NY
BACKGROUND: Sternal wound (SW) infection and dehiscence following median sternotomy from cardiac surgery remain challenging clinical problems with high morbidity. A knowledge of the most common bacteria involved, and how specific bacteria prevalence varies depending on time elapsed from the initial cardiac surgery, can help simplify the choice of targeted antibiotics while awaiting definitive culture results.
METHODS: Records of 505 patients undergoing SW reconstruction by a single surgeon (JAA) from 1996-2018 at a high-volume cardiac surgery center were reviewed. The most common indications for reconstruction were SW infection and dehiscence. At the time of surgery, all patients underwent removal of sternal hardware, thorough debridement, and closure with bilateral pectoralis major myocutaneous advancement flaps. Deep tissue and bone cultures were sent in nearly all cases. Patients were split into Group 1 or 2 based on timing of flap reconstruction after initial cardiac surgery: 0-30 days and >30 days, respectively. Patients without a recorded culture were excluded.
RESULTS: Complete data were available for 400 SW procedures performed by the senior author during this period. Group 1 included 203 patients and Group 2 had 197 patients, with a mean time to SW surgery of 16.3 and 138.1 days, respectively. Intra-operative cultures were positive in 147/203 (72.4%) and 122/197 (61.9%) patients respectively. 44 patients had cultures that grew more than one organism. Chi-squared testing showed a significant difference in the rate of positive cultures in the two groups (p = 0.0004). The most common bacteria in Group 1 infections was Staphylococcus epidermidis, with 54/203 compared to 21/197 in Group 2 (p < 0.0001), while the most common bacterial infection in Group 2 was Methicillin-sensitive Staphylococcus aureus (MSSA) at 22/197 compared to 15/203 in Group 1 (p = 0.23). Methicillin-resistant Staphylococcus aureus (MRSA) was relatively common in both groups: 17/203 in Group 1 versus 21/197 in Group 2. While not statistically significant, Pseudomonas, and Candida were both found in a higher percentage of patients in the late group (p=0.11 and 0.20, respectively). (Table 1) Conclusions: The species of bacteria cultured in SW flap reconstruction vary over time. Staph epidermidis is the most common cause of infection in patients having reconstruction within 30 days of their cardiac surgery, whereas MSSA is the most common bacteria in those undergoing reconstruction more than 30 days later. An awareness of these bacterial differences can help clinicians choose the most appropriate antibiotics while waiting for culture results.
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