Elsevier

Anaerobe

Volume 64, August 2020, 102219
Anaerobe

Clinical microbiology
Anaerobic bacteraemia: A score predicting mortality

https://doi.org/10.1016/j.anaerobe.2020.102219Get rights and content

Highlights

  • Anaerobic bacteraemia accounted for 1.32 cases per 1000 admissions.

  • In 77.2% of all anaerobic bacteraemias were involved Bacteroides, Clostridium and Fusobacterium.

  • Crude mortality for anaerobic bacteraemia was 25.7%.

  • Septic shock, admission in ICU and presence of cancer were associated with high risk or mortality.

Abstract

The objectives of this study were to report those variables which are readily identifiable at the bedside and that are able to predict mortality in patients with bacteraemia caused by anaerobes. Patients with clinically significant anaerobic bacteraemias detected between January 2016 and December 2019 in a tertiary hospital in Granada (Spain) were retrospectively included. Species identification was performed by MALDI-TOF MS and/or molecular methods. Finally, 136 cases of anaerobic bacteraemia were included, being the most frequent anaerobes Bacteroides (45.5%; n = 62), Clostridium (24.2%, n = 33), and Gram-positive anaerobic cocci (16.1%, n = 22). Crude mortality was 25.7%, corresponding to 35 patients who died, with 82.8% of deaths directly attributable to bacteraemia. A multivariable logistic regression model with non-parametric bootstrap estimation identified three variables that were independently and significantly associated with an increased risk of death: 1) hospitalization in the intensive care unit; 2) septic shock; and 3) presence of any kind of cancer. These variables were as recorded at the time that the first positive blood culture was obtained. An index score, obtained from these variables, was calculated and divided patients into two groups with increasing likelihood of mortality resulting from anaerobic bacteraemia. The sensitivity and specificity of a prediction of death based on this model were 65.2% and 97%, respectively.

Introduction

Despite all the advances in medical practice in recent years, it is well known that the presence of anaerobes in the bloodstream continues to have a high associated mortality requiring appropriate treatment [1,2]. The detection rate of anaerobes in blood cultures is around 0.5–11.8% of all bacteraemic episodes, depending on geographic location, and both patient age and condition [3]. Some previously reported factors frequently associated with higher mortality from anaerobic bacteraemia include underlying malignancies, especially hematologic, diabetes and gastrointestinal surgery [2,4]. Many of these studies have provided the current understanding of bloodstream anaerobic infections, but difficulties remain in ascertaining the relationship between mortality and both the infection episode itself and the factors that influence prognosis. Thus, there is a need for predictive models of high-risk patients with anaerobic sepsis. The purpose of the present report was to determine those variables which are readily identifiable at the bedside and that are able to predict mortality in patients with bacteraemia caused by anaerobes. Clinical variables, laboratory findings and specific epidemiological factors were analyzed.

Section snippets

Patients

The clinical records of all patients with positive blood cultures for anaerobic microorganisms at the University Hospital Virgen de las Nieves (Granada, Spain) in the period from January 2016 to December 2019 were reviewed retrospectively. This centre is an approximately 700-bed tertiary care institution, serving as a primary facility for nearly 500,000 inhabitants. Blood cultures were performed at the request of the attending physicians, who made the decisions concerning the patient's

Characteristics of patients

The study included 136 cases of bacteraemia from 136 patients, 55% (n = 75) males, with a mean age of 64 years (ranging from 16 to 97). During the period of study, seven patients/cases were excluded due to the presence of polymicrobial infection. The overall incidence of anaerobic bacteraemia was 1.32 episodes/1000 admissions. One hundred and sixteen (85.3%) of episodes were community-acquired and 20 (14.7%) were hospital-acquired. All for whom data were available were treated, although one did

Discussion

Anaerobic bacteraemia accounted for 1.32 episodes per 1000 admissions at this institution from January 2016 to December 2019. This prevalence seems to be similar than that published in previous series [9]. In that report, moreover, the incidence of anaerobic bacteraemia decreased during the period of study. However, other study showed an increasing tendency for anaerobes bloodstream infection (0.26–0.92%) [10].

Mortality from anaerobic bacteraemia has remained high over the past few years.

Funding

None.

Declaration of competing interest

Authors declare no conflict of interest.

References (17)

There are more references available in the full text version of this article.

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