By Richard R. Watkins, MD, MS, FACP, FIDSA, FISAC

Professor of Internal Medicine, Northeast Ohio Medical University; Division of Infectious Diseases, Cleveland Clinic Akron General, Akron, OH

Dr. Watkins reports no financial relationships relevant to this field of study.

SYNOPSIS: In a multicenter, cluster-randomized crossover trial, researchers compared standard precautions vs. contact isolation for preventing acquisition of ESBL-producing Enterobacterales (ESBL-E) in non-intensive care unit settings. Contact isolation did not decrease the number of hospital-acquired ESBL-E cases, which questions the value of the practice.

SOURCE: Maechler F, Schwab F, Hansen S, et al. Contact isolation versus standard precautions to decrease acquisition of extended-spectrum β-lactamase-producing Enterobacterales in non-critical care wards: A cluster-randomised crossover trial. Lancet Infect Dis 2020;20:575-584.

Healthcare facility-acquired infections increase morbidity, mortality, and healthcare costs. They also can hurt the reputation of healthcare institutions. Numerous guidelines and regulatory agencies have recommended contact isolation for antimicrobial-resistant bacteria, including extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E). Maechler et al sought to determine whether contact isolation had any benefit over standard precautions to prevent the transmission of ESBL-E in patients not in intensive care units (ICUs).

The study was conducted in four European countries: Germany, the Netherlands, Spain, and Switzerland. It was a cluster-randomized crossover trial that included adult patients admitted to general hospital wards. Medical, surgical, or combined medical-surgical wards were randomized to continue with standard precautions alone or to implement contact isolation for 12 months, followed by a one-month washout period, then 12 months of the alternative strategy. Researchers obtained rectal swabs for ESBL-E for enrolled patients on admission, once a week thereafter, and on discharge. Investigators collected ward-level data, including protocol adherence, hand hygiene compliance, and antibiotic consumption. The primary outcome was the incidence density of colonization or infection with ESBL-E, defined as the acquisition rate per 1,000 patient-days at risk at the ward level among patients with a length of stay of more than one week. Acquisition of ESBL-E carriage was defined as recovery of ESBL-E isolates from clinical or surveillance cultures after hospital day 3 following an initial negative culture.

There were 11,368 patients screened twice and, therefore, included in the per-protocol analysis. The incidence density of ESBL-E acquisition was 6.0 events per 1,000 patient-days at risk (95% confidence interval [CI], 5.4-6.7) for contact isolation vs. 6.1 events per 1,000 patient-days at risk (95% CI, 5.5-6.7) for standard precautions (P = 0.971). A multivariable analysis adjusted for length of stay, percentage of patients screened, and prevalence in first screening cultures found an incidence rate ratio of 0.99 (95% CI, 0.8-1.22; P = 0.917) for contact isolation vs. standard precautions. Antibiotic consumption at the ward level did not differ between intervention protocols. Moreover, there was no difference in acquisition of ESBL-producing E. coli (which made up 73% of cases) and K. pneumonia between contact isolation and standard precautions. Healthcare worker compliance with hand hygiene and glove and gown use was similar between the intervention periods.


The concern that patients harboring ESBL-E might contaminate the hospital environment, potentially exposing immunocompromised patients, has been a controversial issue during the past decade. It is well-known that contact isolation requires extra effort and resources, along with potential negative effects on patient satisfaction and safety. Indeed, the need to conserve personal protective equipment (PPE) is particularly salient in light of the COVID-19 pandemic. The study by Maechler et al provides convincing evidence that contact isolation does not reduce acquisition of ESBL-E in general wards compared to standard precautions. This observation makes sense from a molecular epidemiological perspective, since a recent study that used whole-genome sequencing found ESBL-producing E. coli have a low transmission frequency.1

The study has a couple of limitations. First, it was conducted in general hospital wards, so the findings might not be applicable to the ICU setting. However, the known difficulties with contact isolation still would be present, while potential benefits remain uncertain. Second, the delay in laboratory turnaround time in reporting ESBL-E positive samples (median four days, range three to five days) led to delays in implementing contact isolation. Third, the surveillance screening may have missed some of the ESBL-E carriers. This would have resulted in patients being misclassified as having ward-acquired ESBL-E later in their stay. Fourth, it is conceivable that healthcare workers taking care of ESBL-E positive patients assigned to standard precautions may have treated them differently than other patients without ESBL-E. Finally, evidence suggests that patient-to-patient transmission is not the main pathway for the spread of ESBL-E. Instead, acquisitions outside the hospital or selection pressure (i.e., antibiotic use) are more likely to be the major routes of ESBL-E transmission.

Is this study the nail in the coffin for contact isolation to prevent ESBL-E transmission? It appears so, at least for patients on general hospital wards. Further investigation of preventing ESBL-E transmission in ICUs with contact isolation using a similar study design seems warranted. But this study should result in changes to future infection prevention guidelines and current hospital policies.


  1. Biehl LM, Higgins P, Wille T, et al. Impact of single-room contact precautions on hospital-acquisition and transmission of multidrug-resistant Escherichia coli: A prospective multicentre cohort study in haematological and oncological wards. Clin Microbiol Infect 2019;25:1013-1020.