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Aurélien E. Martinez et al
Fig. 1. Risk of infection with ESBL-producing Enterobacteriaceae (ESBL-PE) according to colonization with ESBL-PE on admission (hazard ratio, 25.52; 95% confidence inter- val, 2.40–271.41; P=.007).
decisions of a few individual physicians. Screening was performed only once at ICU admission; thus, colonization by acquisition or selection of ESBL strains during an ICU stay may have been missed. Furthermore, we cannot rule out the possibility that initial colonization may have been missed because only 1 rectal swab was performed, an approach which has previously been shown to have a sensitivity ranging from 77% to 86%.36,37 Because only rectal carriage of ESBL-PE was screened for, colonization of other body sites might have been missed. Clinical staff performed the rectal swabs, and the manner in which the samples were collected may have differed, which might have influenced sample adequacy. In addition, a relevant number of patients were under an ESBL-PE active antibiotic therapy at the time of screening (ie, 20.9% of all patients received carbapenem treatment prior to ICU admission), which might have led to false-negative results. Our study design did not allow us to draw any conclusions regarding the number needed to screen: All patients were screened in our cohort, and carbapenem use after introduction of screening was not compared to the use prior to this intervention. The strength of our study is the systematic inclusion of all
consecutive patients in a relatively short time, which limited the effect of increasing ESBL-PE prevalence over time. In comparison to different studies, including the French study,28 we distinguished between the antibiotic use before and after the availability of the screening result. Therefore, we were able to estimate the impact of the actual screening procedure. Our study shows that screening for ESBL-PE colonization on
ICU admission can help to identify patients at risk for ESBL-PE infection and may therefore facilitate the correct allocation of empiric carbapenem treatment.
Author ORCIDs. Aurélien Emmanuel Martinez,
Fig. 2. Risk of carbapenem exposure according to colonization with ESBL-producing Enterobacteriaceae on admission (hazard ratio, 2.42; 95% confidence interval, 1.01– 5.79; P =.047).
patients with a negative screening result, which is supported by a recent French study that showed much greater carbapenem expo- sure for ESBL-PE–colonized patients.28 This difference occurred despite screening not being accompanied by an antimicrobial stew- ardship intervention; however, the results were available to the treating physicians through the laboratory system and seem to have influenced their prescription strategies. Carbapenem expo- sure differed between patients colonized and not colonized with ESBL-PE, as determined by competing risk regression analyses but not by simple comparison of proportions. This finding points to the impacts of time to rather than simply presence or absence of carbapenem exposure, as well as death (representing a competing risk). The high number of patients in our study with exposure to in-hospital antibiotics prior to the ESBL screening made the choice of a carbapenem as an empiric therapy more likely as an escalation strategy in the case of suspected new-onset infection. Our study has several limitations. The data were collected retro-
spectively and thus were subjected to documentation bias. The absolutenumber of patients in general, thenumber of patients with ESBL-PE colonization and even more ESBL-PE infection was low. This limited the study’s power for further multivariable analyses, but it reflects the situation in a low endemicity setting. This study was conducted at a single center; thus, our findings might not be generalizable to other settings and may have been influenced by the
0000-0001-9709-0644
Financial support. The study was conducted using internal funds of the University Hospital Basel.
Conflict of interest. All authors report no conflicts of interest relevant to this article.
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