Mediastinitis due to Gram-negative bacteria is associated with increased mortality

Abstract

The aim of this study was to describe the features of a large cohort of patients with postoperative mediastinitis, with particular regard to Gram-negative bacteria (GNB), and assess their outcome. This bicentric retrospective cohort included all patients who were hospitalized in the Intensive Care Unit with mediastinitis after cardiac surgery during a 9-year period. Three hundred and nine patients developed a mediastinitis with a mean age of 65 years and a mean standard Euroscore of six points. Ninety-one patients (29.4%) developed a GNB mediastinitis (GNBm). Of the 364 pathogens involved, 103 GNB were identified. GNBm were more frequently polymicrobial (44% versus 3.2%; p <0.001). Being female was the sole independent risk factor of GNBm in multivariate analysis. Initial antimicrobial therapy was significantly more frequently inappropriate with GNBm compared with other microorganisms (24.6% versus 1.9%; p <0.001). Independent risk factors for inappropriateness of initial antimicrobial treatment were GNBm (OR = 8.58, 95%CI 2.53-29.02, p 0.0006), and polymicrobial mediastinitis (OR = 4.52, 95%CI 1.68-12.12, p 0.0028). GNBm were associated with more drainage failure, secondary infection, need for prolonged mechanical ventilation and/or use of vasopressors. Thirty-day hospital mortality was significantly higher with GNBm (31.9 % versus 17.0%; p 0.004). GNBm was identified as an independent risk factor of hospital mortality (OR = 2.31, 95%CI 1.16-4.61, p 0.0179).

Exceptional association of two species of bacteria causing mediastinitis: Haemophilus influenzae (H. influenzae) and Aggregatibacter aphrophilus (A. aphrophilus)

“…In a wide range of mediastinitis in a 8-years study carried out in France (Charbonneau et al) 3 cases of Haemophilus influenzae were found; that being a percentage of 0.9% [7]. …”

“…It is primarily TEM-type enzyme. A decreased susceptibility to beta-lactams by modification of the penicillin binding proteins (PBPs) target this antibiotic family is another mechanism which can add an efflux mechanism [7, 8, 10, 12, 13]. …”

Gram-negative rod bacteremia after cardiovascular surgery: Clinical features and prognostic factors

“…; therefore, clinicians may not consider them a source of GNRB. According to the literature, Gram-negative organisms account for 22e28.3% of mediastinitis, 12,13 and 20e30% of surgical site infections. 3,14 This study provides evidence that several factors are associated with increased mortality from GNRB after CVS.…”

Manejo de mediastinitis posterior a cirugía cardíaca: reporte de caso

“…La mediastinitis posterior a cirugía cardíaca tiene una prevalencia que va desde el uno al dos por ciento [1][2][3][4][5][6][7] . Adicionalmente, en cirugía coronaria incrementa los costos en los hospitales hasta el 240% comparado con los procedimientos no complicados 2 .…”

“…La mediastinitis secundaria a bacterias gramnegativas está asociada a una disminución en la sobrevida, en muchas ocasiones debido a un inapropiado esquema antibiótico 3 . En estos casos, la diseminación hematógena prevalece más que la inoculación directa.…”