Additional contact precautions (ACP) have been endorsed by International Recommendations in patients with colonisation or infection by multidrug-resistant organisms (MDRO) [1, 2]. Contact isolation (CI), considered initially as the holy grail of the interruption of transmission of MDROs, currently remains debated [3, 4]. Suboptimal contact of healthcare personnel with the patients has been associated with service care errors including falls, pressure ulcers, fluid/electrolyte disorders and suboptimal documentation of vital signs or physician notes. Patients’ dissatisfaction and stress as well as increased healthcare costs are the major downsides of CI [3]. In view of the divergent opinions in the literature, infection control practices in ICU vary considerably. In this narrative review, we will focus on the most relevant studies, with messages in line with the principle “less is more” (Table 1). In the present manuscript, we considered “less CI” as surrogate to “not universal" or “targeted” CI (and evidently not “no CI”). However, we also discuss studies in which CI seems less important or less effective compared to other pivotal infection control measures, therefore, less desirable. Search methods are shown in Supplement Table.

Table 1 Contemporary studies delivering the message “less contact isolation in the ICU is more”
Full size table

The efficacy of CI over properly enforced standard precautions with particular focus on adherence to hand hygiene has been questioned. Huskins et al. performed universal screening of patients and then pre-emptive isolation followed by barrier precautions for identified carriers; no significant change in acquisition of MRSA or VRE was demonstrated [4]. Also, Cepeda et al. showed that transfer of MRSA-colonised patients into single rooms or cohorting did not confer to reduced cross-infection [5]

As far as MDR Gram-negative bacteria (MDR-GNB) are concerned, despite international recommendations, no single infection control approach (and particularly not CI) alone was associated with positive outcomes, especially in endemic settings. A recent systematic review and network meta-analysis evaluating (1) standard care (including contact precautions), (2) antimicrobial stewardship, (3) environmental cleaning, (4) source control or (5) decolonization methods for the prevention of multidrug-resistant Gram-negative bacteria (MDR-GNB) in adult Intensive Care Units (ICUs) showed that only four-component strategies adopting components (1)–(5) were effective to prevent MDR-GNB acquisition [6]. Environmental cleaning seems important component for Acinetobacter baumannii, whereas decolonization strategy was pivotal in K. pneumoniae albeit data derived from low endemicity settings [6]. Sypsa et al. using a Ross-Macdonald model, showed that screening, contact precautions and particularly hand hygiene among a multifaceted infection control bundle (including CI), were the major contributors in the containment of Carbapenemase-producing Klebsiella pneumonia in an endemic surgical setting [7]. In this study, cohorting was more common than strict isolation due to intrinsic institutional barriers. Nevertheless, less strict isolation may still prove to be highly effective, provided that contact precautions remain fully functional.

In a prospective multicenter ICU trial by Derde and colleagues, in the context of a rigorous compliance with hand hygiene and universal chlorhexidine body washing, screening and CI of carriers do not reduce acquisition rates of MDRO, irrespective of rapid or conventional screening. However, a reduction in MRSA acquisition was noted [8]. Data from the previous and other studies argue for targeted and non-universal screening and CI measures in endemic environments or outbreaks by ESBL-producing non-Escherichia coli Enterobacterales, whereas ESBL-E. coli seems to be associated with less CI demands, particularly in settings where effective standard precautions are in place [9].

Ledoux et al., in a before–after single-center non-inferiority study, showed that a targeted isolation strategy at ICU admission was not inferior to a systematic isolation strategy regarding ICU-acquired infection related to MDRO (including key resistant both Gram-positive and -negative pathogens). With the targeted approach, CI was avoided in almost one-third of patients [10]. In another sequential single-center observational study in a surgical ICU, the authors showed that a targeted isolation screening policy on ICU admission was safe compared with universal screening and isolation, resulting in similar rates of ICU-acquired MDRO colonization or infection during both study periods [11].

On the other hand, many studies have shown an increased rate of undesirable adverse events associated with CI [3]. In a study comparing the frequency of adverse events according to the isolation status in an ICU cohort population, the authors found five medication errors or adverse events that were significantly more frequently observed in patients under strict isolation: hypoglycaemia, hyperglycaemia, errors in administration of anticoagulants and ventilator-associated pneumonia (VAP) due to MDRO [12]. Searcy et al. showed that CI for MRSA colonisation was associated with over-sedation, prolonged ICU stay and mechanical ventilation [Searcy] [13].

Isolation capability varies across countries and settings. Dhar et al. showed that as the need for isolation is increasing, compliance with other measures is decreasing. There was a threshold of 40% for isolation within the unit, above which compliance with CI precautions (particularly hand hygiene) dropped significantly [14]. In a mathematic model, Gurieva et al. have shown that isolation capability is a major determinant of cost-saving curves. Targeted patient screening (based on previous carrier status) combined with screening of ICU-patients was the most cost-effective strategy when associated with an isolation capability of 25%. Better isolation capability is expected to render more extended screening strategies cost saving [15]. Therefore, CI local recommendations should be balanced on these issues.

We are convinced that CI will remain an important aspect of infection control, yet not the holy grail. Scientific evidence questioning its pivotal role particularly in the multifactorial arena of MDR-GNB persistence, permit us to state: “Less CI”, is probably “more” in the ICU setting. Targeted and locally adapted contact isolation practices can avoid undesired adverse events in the patient’s management, spare healthcare financial and human resources to be allocated in other preventive components, and obviate patient-family stress. Its contribution in contemporary medicine cannot be viewed without rapid screening tools to be applied to targeted group of patients and certainly without strictly supervised hand hygiene. However, purpose-constructed studies are required to verify actual ranking of infection control components in each epidemiologic milieu.