IJCS | Volume 31, Nº2, March / April 2018

166 Factors associated with mediastinitis that were observed in the logisticmodel: longer time of post‑surgical hospitalization, occurrence of post-surgical fever and higher number of pre-surgical risk factors. Each increase of 1 day in post-surgical hospitalization increased the chance of developing mediastinitis by 3.2% and, with each increase of one pre-surgical risk factor, this chance increased by 57.3%. The occurrence of fever after surgery increases the chance of developingmediastinitis bymore than ten-fold (Table 3). Discussion This work was motivated by a case-control study carried out in the same institution from January 2005 to January 2007, with 54 patients, with a mean age of 59.7 years, submitted to sternotomy (18withmediastinitis). Most patients were males (72.2% for the whole sample and 66.7% among those who developed mediastinitis), and 86% were submitted to CABG. Mortality was 22.2% in the sample and 33.3%among thosewithmediastinitis. 15 The results of the present study showed similar results to those of the previous study regarding age, male predominance and type of surgery (CABG), with higher proportions among those who developed mediastinitis. Regarding death, mortalitywas lower than that previously observed, includingamongpatientswhohadmediastinitis, but these values are still high, as shown in the literature (14% to 47%). 3 The median time of post‑surgical hospitalization was higher in patients diagnosed with mediastinitis in both studies, showing greater severity of the cases and impact on hospital costs. The results indicate the need to investigate the factors responsible for the development of this complication, aiming at the prevention and control of health care‑associated infections, aiming to improve quality of care, patient safety and to reduce costs. Regarding the patient profile, incidence ofmediastinitis andmortality, Souza et al. 4 evaluated patients submitted to surgical interventions between 1991 and 2000 and found amean age of 51.9 years, most of themsubmitted to CABG (also among those who developed mediastinitis) and a predominance of female patients. The incidence of post-sternotomymediastinitis was 1.6%and themortality rate was 21.6%. Sá et al. 1 evaluated patients submitted to CABG between 2007 and 2010, in whom the mean age was 62.14 years, with a predominance of males. The incidence of mediastinitis was 5.6% and themortality rate was 32.1%. Magalhães et al. 3 evaluated patients submitted to cardiac surgery, from 2007 to 2009; the mean age was 60 years and most of them were males. CABG was performed in 76.2% of the patients who developed mediastinitis; only 2.3% of the patients developed post‑sternotomy mediastinitis and 33% died. Table 2 – Microorganisms found in the bacteriological diagnosis of patients with mediastinitis Microorganism n = 13 n (%) Gram -positive 6 (46.2) Staphylococcus aureus 4 (30.7) Coagulase- negative Staphylococcus 1 (7.7) Coagulase- negative Staphylococcus , Streptococcus agalactiae* 1 (7.7) Gram -negative 6 (46.2) Enterobacter sp 1 (7.7) Acinetobacter baumannii 1 (7.7) Stenotrophomonas maltophilia 1 (7.7) Klebsiella pneumoniae , Pseudomonas aeruginosa * 1 (7.7) Klebsiella pneumoniae 1 (7.7) Escherichia coli, Proteus mirabilis and Klebsiella pneumoniae* 1 (7.7) No information 1 (7.7) *Patients with more than one microorganism. Pinto et al. Factors Associated with Post-Sternotomy Mediastinitis Int J Cardiovasc Sci. 2018;31(2)163-172 Original Article