Carbapenem-resistant Enterobacteriaceae in patients admitted to the emergency department: prevalence, risk factors, and acquisition rate

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Summary

Background

Carbapenem-resistant Enterobacteriaceae (CRE) have been reported worldwide and are associated with high mortality rates. Intestinal colonization acts as a reservoir and fosters exchange of resistance mechanisms.

Aim

To investigate the prevalence of patients harbouring CRE on hospital admission, risk factors associated, and the acquisition rate within the emergency department (ED).

Methods

This was a cross-sectional survey with 676 patients consecutively admitted to the ED study during the months of May to July 2016. A questionnaire was performed and rectal swabs were collected from patients on admission, for culture and for multiplex real-time polymerase chain reaction (PCR). If the patient was hospitalized for more than one week in the ED, samples were taken again to determine the acquisition rate of CRE.

Findings

Forty-six patients were colonized; all positive PCR were Klebsiella pneumoniae carbapenemase. The acquisition rate was 18%. Previous exposure to healthcare in the last year, liver disease, and use of antibiotics in the last month were risk factors for colonization. Six patients with no previous exposure to healthcare were CRE-colonized on admission, suggesting transmission of CRE within the community.

Conclusion

Screening of high-risk patients on admission to the ED is a strategy to early identify CRE carriage and may contribute to control CRE dissemination.

Introduction

Carbapenemases became a great concern in the last 15 years since the first description of Klebsiella pneumoniae carbapenemase (KPC) [1]. Enterobacteriaceae have become increasingly antibiotic resistant. The emergence of extended-spectrum β-lactamase (ESBL) producers, and then KPC, means that infections with Enterobacteriaceae have been increasingly difficult to treat, leading to substantial economic and human costs [2].

KPC was first described in 1996 in North Carolina, USA; since then, it has been reported worldwide, in both Enterobacteriaceae and non-Enterobacteriaceae [2], [3]. Infection with KPC-producing bacteria has been associated with high mortality rates and poor outcomes [4]. Epidemiological studies demonstrate that K. pneumoniae isolates belonging to sequence type 258 (ST258) are even more virulent when bearing blaKPC-2 [5].

The emergence of new determinants of antimicrobial resistance, their spread, and the lack of new drugs pose a challenge, indicating the possible end of the ‘antibiotic era’. This triggered an alarm by the World Health Organization that declared carbapenem-resistant Enterobacteriaceae (CRE) as one of three greatest menaces to human health [6].

KPC and other carbapenemase genes, such as the New Delhi-metallo-β-lactamase (NDM) and other metallo-β-lactamases, such as VIM and IMP family enzymes, are usually harboured in plasmids, which enable them to spread to other bacteria. In this context, intestinal carriage is a major concern for the infection control practitioner, due to the potential for the gut to act as a reservoir for multidrug-resistant organisms (MDROs), and as an environment in which resistance mechanisms can be exchanged between bacteria. These factors may lead to nosocomial dissemination of CRE and to outbreaks [7].

Many hospitals use screening for CRE carriage as one strategy to control cross-transmission. Screening is most usually undertaken in patients in intensive care units (ICUs); early identification of colonized patients allows implementation of contact precautions to prevent the transmission to other patients [8], [9], [10]. In one ICU in Brazil, colonization with CRE was reported in 30.4% of patients [11]. In our hospital, the prevalence of CRE carriage on admission to the ICU is ∼20% (unpublished data), but the times and places in which colonization takes place are not yet known.

Almost 30% of our patients are admitted via the emergency department (ED), which is a referral unit in our public health system. Patients come from all parts of the country. Overcrowded wards and ICUs lead to a delay in transfers from EDs to other units. Thus patients experience long periods of care in overcrowded EDs, which probably facilitates cross-transmission of MDRO. However, the relative contributions of the community, EDs, and ICUs to the acquisition of CRE is not clear. The aims of this study were to describe the prevalence of CRE carriage among patients on admission to the ED, to identify risk factors associated with this colonization, and to determine the incidence of CRE acquisition during hospital stay in the ED.

Section snippets

Methods

We conducted a prevalence study at the ED of Hospital das Clínicas, a 1000-bed teaching hospital affiliated to the University of São Paulo, Brazil. The ED is responsible for 30 hospital admissions per day, and has a theoretical capacity of 50 beds. Generally, however, its capacity is exceeded and it is not uncommon to have more than 90 patients hospitalized in this area.

During the period from May 31st to July 7th, 2016, a total of 676 patients were consecutively admitted to the ED and

Results

In all, 676 patients were included in this study; 52% (353 patients) were male, with a mean age of 57 years (range: 2–94; median: 60). Two culture-negative patients were excluded because they did not collect samples for PCR.

On admission, 46 (6.8%) patients were colonized by CRE based on at least one laboratory method. Culture was positive for 38 (5.6%) patients (all isolates identified as Klebsiella pneumoniae); PCR was positive for 36 (5.3%) (all KPC) (Table I). The mean age of the colonized

Discussion

The prevalence of CRE colonization on admission to the ED was 6.8%, with an acquisition rate of 18%. CRE colonization was found in six patients with no exposure to healthcare during the previous year. The patients' stay in the ED was long, as 45% of the patients were hospitalized for at least one week. Our study also describes liver disease as a new risk factor for CRE colonization, and confirms known risk factors such as previous exposure to healthcare and previous use of antibiotics.

KPC is

Acknowledgements

We thank the infection control team that worked on collecting data and the emergency department staff who helped to collect the samples.

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