title: Polymicrobial bloodstream infections: Epidemiology and impact on mortality.
abstract: The aim of this study was to investigate the impact of polymicrobial bloodstream infections (pBSIs) on the outcome of sepsis in an area where antimicrobial resistance is of concern. This was a retrospective analysis of data collected prospectively from patients developing BSI outside of an intensive care unit (non-ICU patients) or after ICU admission. Demographics and clinical characteristics were compared for patients with pBSI versus monomicrobial BSI (mBSI) and following stratification by ICU or non-ICU and severity of sepsis status. Possible risk factors for adverse outcome were explored by multivariate analysis, and outcomes were measured by Cox regression analysis. Among 412 patients with BSI, 47 patients (11.4%) with pBSI were recorded; compared with patients with mBSI, they had significantly higher APACHE II scores and presented more frequently with severe sepsis/septic shock. The all-cause 28-day mortality was significantly higher for pBSI versus mBSI (38.3% vs. 24.7%; P=0.033), whereas appropriateness of treatment was comparable (78.7% vs. 86.6%). Primary bacteraemia by combinations of Enterococcus faecalis, Klebsiella pneumoniae and Acinetobacter baumannii was predominant among pBSIs; in mBSIs, urinary tract infections by Escherichia coli, K. pneumoniae or Pseudomonas aeruginosa predominated. Multivariate analysis demonstrated pBSI as a significant contributor to 28-day mortality (HR=1.86; P=0.039), along with presence of two or more co-morbidities (HR=2.35; P=0.004). In conclusion, pBSIs differed epidemiologically from mBSIs, with the emergence of enterococcal species, and portended an almost two-fold increased risk of 28-day mortality. Prospective studies are warranted to elucidate possibly modifiable factors.
authors.affiliation: Department of Internal Medicine, Argos General Hospital, Argos, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Pavlaki
authors.affiliation: 4th Department of Internal Medicine, University of Athens, Medical School, Athens, Greece. Electronic address: gpoulakou@gmail.com.
authors.forename: Garyphallia
authors.initials: G
authors.lastname: Poulakou
authors.affiliation: Intensive Care Unit, Ippokrateion General Hospital, Athens, Greece.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Drimousis
authors.affiliation: 1st Department of Internal Medicine, 'G. Gennimatas' General Hospital, Athens, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Adamis
authors.affiliation: Intensive Care Unit, Bodossakis Hospital, Ptolemaida, Athens, Greece.
authors.forename: Efterpi
authors.initials: E
authors.lastname: Apostolidou
authors.affiliation: Department of Medicine and Research Laboratory of Internal Medicine, Medical School, University of Thessaly, Larissa, Greece.
authors.forename: Nikolaos K
authors.initials: NK
authors.lastname: Gatselis
authors.affiliation: Department of Surgery, Nafplio General Hospital, Nafplion, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kritselis
authors.affiliation: Intensive Care Unit, Laikon General Hospital, Athens, Greece.
authors.forename: Anna
authors.initials: A
authors.lastname: Mega
authors.affiliation: 2nd Department of Internal Medicine, Sismanoglio General Hospital, Athens, Greece.
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Mylona
authors.affiliation: 2nd Department of Urology, University of Athens, Medical School, Athens, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Papatsoris
authors.affiliation: Department of Internal Medicine, Argos General Hospital, Argos, Greece.
authors.forename: Apostolos
authors.initials: A
authors.lastname: Pappas
authors.affiliation: Intensive Care Unit, Tzaneion General Hospital, Piraeus, Greece.
authors.forename: Athanassios
authors.initials: A
authors.lastname: Prekates
authors.affiliation: 4th Department of Internal Medicine, University of Athens, Medical School, Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Raftogiannis
authors.affiliation: Department of Internal Medicine, Sparti General Hospital, Sparti, Greece.
authors.forename: Kalliopi
authors.initials: K
authors.lastname: Rigaki
authors.affiliation: 2nd Department of Internal Medicine, Sismanoglio General Hospital, Athens, Greece.
authors.forename: Kalliopi
authors.initials: K
authors.lastname: Sereti
authors.affiliation: Department of Therapeutics, Alexandra Hospital, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Sinapidis
authors.affiliation: 2nd Department of Critical Care Medicine, University of Athens, Medical School, Greece.
authors.forename: Iraklis
authors.initials: I
authors.lastname: Tsangaris
authors.affiliation: 4th Department of Internal Medicine, University of Athens, Medical School, Athens, Greece.
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Tzanetakou
authors.affiliation: Intensive Care Unit, Sotiria General Hospital, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Veldekis
authors.affiliation: Intensive Care Unit, Korgialeneio-Benakeion Hospital, Athens, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Mandragos
authors.affiliation: 4th Department of Internal Medicine, University of Athens, Medical School, Athens, Greece.
authors.forename: Helen
authors.initials: H
authors.lastname: Giamarellou
authors.affiliation: 2nd Department of Critical Care Medicine, University of Athens, Medical School, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Dimopoulos
keywords: Appropriate treatment; Enterococcal infections; Nosocomial bacteraemia; Polymicrobial infections; Primary bacteraemia; Severe sepsis