**3. Microbiology of DSWI and routes of infection**

Staphylococci, either S. aureus (SA) or coagulase-negative Staphylococcus (CONS) represent the most causative organism of DSWI, accounting for 60 to 80% of cases [34]. The proportion of individual strains of Staphylococcus and their methicillin-sensitivity varies between countries and institutions, reflecting their long-term hygienic and antibiotic policies [35]. Although surgical site infections are typically perceived to be an exogenous problem related to exposure to healthcare workers, the most causative pathogens are endogenous from patient's own skin or mucosal flora [36,37]. Nasal carriage of SA has been identified as a potential risk factor for DSWI [38], and genetically identical SA from nasal flora have been cultivated from sternotomy wounds [39]. Unlike SA which caused a more aggressive presen‐ tation, CONS infection accompanied with bacteremia as observed in 50-60% of cases [34, 40] had a rather indolent course, clinically manifested later, and was more prone to recurrence [41, 42]. DSWI is diagnosed in 40-70% of patients post-discharge, thus post-discharge surveillance of up to 90 days is recommended [43]. Gram negative strains contribute less commonly in the pathogenesis of DSWI and mostly translocate from other host site infections, such as pneu‐ monia, urinary or abdominal infections [34]. Finally, no significant difference in mortality was observed between DSWI infections caused by CoNS, when compared to SA, or Gram-negative pathogens [34]. Mekontso-Dessap et al suggested that DSWI caused by methicillin-resistant SA (MRSA) may have worse actuarial survival than sensitive strains (MSSA) in terms of 1 month, 1-year, and 3- year survival (60.0%±12.6%, 52.5%±-3.4%, and 26.3%±19.7% versus 84.6% ±7.1%, 79.0%±8.6%, and 79.0%±-8.65, p=0.04), and a regression analysis revealed MRSA as an independent risk factor for overall mortality [44].

the last decade consistently confirm long-term complications of patients with mid-, and long term survival rates who were successfully treated for DSWI (Table 3) [8,11,12,14,15,18,22,46]. Specific reasons for worsening of long-term survival are not yet clear. Risnes et al reported significantly higher cardiac-related deaths in the post-DSWI group (34.6 vs. 21.4%, p<0.006) and poorer survival for males ten years after surgery [15]. In contrast with this data, Sjoegren et al and Bailot et al showed unimpaired long-term survival of DSWI patients in comparison

with patients who had uncomplicated surgery once NPWT was used [18,46].

Loop FD et al [6] 1985-1987 3-year survival of 62.5% compared to 69.0% survival for patients with positive

Braxton et al [8] 1992-1996 The adjusted survival rates at 30 days, 1 year, and 4 years were 93%, 78%, and 65%

Filsouri et al [12] 1998-2005 Survival rates at 1,3, and 5 years were 72.4%, 64.3% and 55.8% for patients with

Risnes et al [15] 1989-2000 The 10-year, long-term survival for patients with mediastinitis was 49.5%,

Sjoegren et al [18]1999-2004 The actuarial survival at 1 year, 3 years, and 5 years was 92.9% , 89.2%, and 89.2%

Bailot et [46] 1992-2007 Survival in patients with DSWI showed freedom from all-cause mortality at 1, 5 and

DSWI treated conventionaly(p = 0.02)

**Table 3.** Analyses of compared mid-term and long-term survival of patients with DSWI with non-DSWI patients

cultures. Overall, the 3-year survival was 75%, which is significantly below previously reported 5-year and even 10-year survival for isolated coronary bypass

Current Challenges in the Treatment of Deep Sternal Wound Infection Following Cardiac Surgery

http://dx.doi.org/10.5772/55310

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1996-1998 DSWI patient had a 1-year survival of 78% vs. 99% for non-infected CABG patients,

DSWI compared with 93.8%, 88% and 82% for the control (p<0.001)

1992-2002 Freedom from all cause mortality in patients in whom DSWI developed at 1 year, 5

compared with 71.0% in non-mediastinitis patients (p<0.01)

2001-2005 Unadjusted freedom from all-cause mortality in patients with DSWI at 1 year, 2

among patients with mediastinitis and 97%, 95%, and 89% without mediastinitis,

years, and 10 years after the operation was 66.2%, 50.8%, and 40.6% respectively, compared with 87.2%, 72.8%, and 54.3% in patients without DSWI (p=0.0007)

for patients with mediastinitis and 96.5%, 92.1%, and 86.9 for those without

years, and 3 years after surgery was 78.6 ± 4.8% (95% CI 69–88.2%), 75.6 ± 5.0% (95% CI 65.6–85.6%) and 69.4 ± 5.8% (95% CI 57.8–81%) respectively compared with 92.8 ± −0.4% (95% CI 92.4–93.2%), 90.7 ± 0.5% (95% CI 90.2–91.2%) and 87.7 ± 0.6% (95% CI 87.1–88.3%) for patients without DSWI (p < 0.001)

10 years to be, respectively, 91.8%, 80.4% and 61.3% compared with 94.0%, 85.5% and 70.2%, respectively, for patients (p = 0.01). Adjusted survival for patients with DSWI treated with NPWT was 92.8%, 89.8% and 88.0%, respectively, at 1, 2 and 3 years, compared with 83.0%, 76.4% and 61.3%, respectively, for patients with

**Survival analysis**

respectively (p<0.001)

mediastinitis(p=0. 578)

patients

p=0.0001

**Authors Patients´**

Hollenbeak et al

Toumpoulis et al

Sachithanandan et al [22]

[11]

[14]

**enrollement**
