SWISS MEDICAL WEEKLY: ICU INFECTIONS.

Review article | Published 24 September 2014, doi:10.4414/smw.2014.14009
Cite this as: Swiss Med Wkly. 2014;144:w14009

Enterococci, Clostridium difficile and ESBL-producing bacteria: epidemiology, clinical impact and prevention in ICU patients

Jan A. Sidler, Manuel Battegay, Sarah Tschudin-Sutter, Andreas F. Widmer, Maja Weisser

Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Switzerland

Summary

Abbreviations

ARE  ampicillin-resistant enterococci

CI  confidence interval

ESBL  extended-spectrum ß-lactamase

ESBL-GNB  extended-spectrum ß-lactamase producing gram-negative bacteria

ICU  intensive care unit

MRSA  methicillin-resistant Staphylococcus aureus

OR  odds ratio

VRE  vancomycin-resistant enterococci

Most hospital-acquired infections arise from colonising bacteria. Intensive care patients and immunocompromised individuals are at highest risk for microbial invasion and subsequent infection due to multiple invasive procedures in addition to frequent application of chemotherapeutics and presence of poor microperfusion leading to mucosal disruption. In this narrative review, we summarise the literature on bacterial colonisation in intensive care patients, in particular the epidemiology, the clinical impact and respective infection control strategies of three pathogens, i.e., Enterococcus spp., extended-spectrum ß-lactamase producing gram-negative bacteria and Clostridium difficile, which have evolved from commensals to a public health concern today.

Key words: Clostridium difficile; colonisation; enterococcus; enterobacteriaceae; ESBL; infection; intensive care unit; multidrug-resistant; outcome; VRE

Introduction

Infections are the leading cause of death in intensive care units (ICUs) worldwide and mortality in infected ICU patients is more than twice as high compared to non-infected patients [1, 2]. Despite significant advances in intensive care therapy and infection prevention, incidence of nosocomial infections in ICU patients has remained high [1, 3]. The bacteria causing most hospital-acquired infections are staphylococci including methicillin-resistant S. aureus (MRSA), enterococci including vancomycin-resistant enterococci (VRE), Candida spp., Clostridium difficile and different often multidrug-resistant gram-negative bacteria [1].

In healthy individuals, an ecological community of commensals, symbiotes and pathogens – the microbiome – is in equilibrium with the host. If anatomical barriers or host defenses are disrupted, invasion of colonising bacteria and subsequent infection can arise [4].

In ICU patients, multiple invasive procedures (e.g., central venous catheters) and the presence of poor microperfusion lead to integrity loss of skin and mucosae with risk of invasive infection [5]. Furthermore, ICU patients are per se immunocompromised due to the severity of the disease [6].