Sternal wound infections following cardiac surgery and their management: a single-centre study from the years 2016–2017

Introduction
Despite improvements in surgical management, sternal wound infection (SWI) following cardiac surgery remains a significant complication.

Aim
To evaluate pathogens involved in SWI following median sternotomy.

Material and methods
We enrolled 164 patients who experienced prolonged sternal wound healing following open-heart surgery. The inclusion criteria were as follows: prolonged sternal wound healing following cardiac surgery via median sternotomy and complete results of microbiological culture obtained from the sternal swab. The exclusion criteria were as follows: partial sternotomy, patients with mechanical sternum dehiscence and incomplete clinical data. Swabs provided information on the type of microorganism present in the wound and the susceptibility of the microorganism to specific antibiotics.

Results
One hundred and fourteen (69.5%) patients aged 68 (interquartile range: 60–76) years developed SWI with positive culture. The in-hospital mortality rate was 21.0% in this group. The most common pathogens included Staphylococcus epidermidis (26.6%), Enterococcus faecium (12.2%), Staphylococcus aureus (11.4%), Klebsiella pneumoniae (8.4%), and Pseudomonas aeruginosa (6.8%). In most of the cases the isolated Staphylococcus epidermidis was methicillin-resistant (n = 57, 43.5%). Enterococcus faecium was vancomycin-resistant in 11 (8.3%) cases and high-level aminoglycoside resistant (HLAR) in 13 (9.9%) cases. Klebsiella pneumoniae had the extended-spectrum β-lactamase (ESBL) mechanism in 14 (10.6%) cases. Among 114 culture-positive patients, 48 (42.1%) had polymicrobial infection of the sternal wound.

Conclusions
Microorganisms associated with SWI in our study were mainly commensals, with the most common pathogen being Staphylococcus epidermidis.