Modelled Target Attainment after Temocillin Treatment in Severe Pneumonia: Systemic and Epithelial Lining Fluid Pharmacokinetics of Continuous versus Intermittent Infusions.

The objective of this article is to describe the population pharmacokinetics (PK) of temocillin administered via continuous infusion (CI) versus intermittent infusion (II) in critically ill patients with pneumonia. Secondary objectives included characterization of epithelial lining fluid (ELF)/plasma penetration ratios and determination of the probability of target attainment (PTA) for a range of MICs. Thirty-two mechanically ventilated patients who were treated for pneumonia with 6 g of temocillin daily for in vitro sensitive pathogens were assigned to either the II (2 g every 8 h over 0.5 h) or the CI (6 g over 24 h after a loading dose of 2 g) group. A population pharmacokinetic model was developed using unbound plasma, and total ELF concentrations of temocillin and related Monte Carlo simulations were performed to assess PTAs. The area under the concentration-time curve from 0 to 24 h (AUC0-24) ELF/plasma penetration ratio was 0.73, at steady state, for both modes of infusion and whatever the level of creatinine clearance. Monte Carlo simulations showed that for the minimal pharmacodynamic (PD) targets of 50% T > 1× MIC (II group) and 100% T > 1× MIC (CI group), PK/PD breakpoints were 4 mg/L in plasma and 2 mg/L in ELF and 4 mg/L in plasma and ELF, respectively. The breakpoint was 8 mg/L in ELF for both modes of infusion in patients with creatinine clearance (CLCR) < 60 mL/min/1.73 m2. While CI provides better PKPD indexes, the latter remain below available recommendations for systemic infections, except in the case of moderate renal impairment, thereby warranting future clinical studies in order to determine the efficacy of temocillin in severe pneumonia.

[Role of physical and rehabilitation medicine in the aftermath of SARS-CoV-2 disease]. / Rôle de la médecine physique et réadaptation fonctionnelle dans les suites d'une atteinte au SARS-CoV-2.

2020 will be remembered as the year of SARS-CoV-2 pandemic which confined most of the world's population at home. Rehabilitation units will have to face specific challenges to protect the vulnerable in-patients. Moreover, they must prepare for post-COVID-19 patients who might suffer from illness consequences or present a post intensive care syndrome secondary to the increased ICU length of stay. The purpose of this paper is to highlight the deficiencies of post-COVID-19 patients and suggest a decision algorithm to best match their needs.

L'année 2020 restera marquée par la pandémie de SARS-CoV-2, originaire de Chine, qui a confiné une grande partie de la population mondiale. Les services de médecine physique et rééducation fonctionnelle ont dû adopter des mesures spécifiques afin de limiter la contagion de leurs patients, appartenant à la population à risque. Ils se préparent également à l'accueil et à la prise en charge des patients post-COVID-19 présentant des séquelles secondaires à l'infection ou à l'hospitalisation prolongée en réanimation, responsable d'un syndrome post-soins intensifs. L'objectif de cet article est de dégager les différentes pathologies auxquelles les médecins rééducateurs seront confrontés et de proposer un algorithme décisionnel pour orienter la prise en charge rééducative.

Continuous infusion of cefepime and neurotoxicity: a retrospective cohort study.

OBJECTIVES: Neurotoxicity related to cefepime is increasingly reported in the literature but specific data concerning continuous infusion (CI) of the drug are still lacking. Our primary objective was to evaluate the incidence of neurotoxicity related to CI of cefepime and the associated risk factors. Our secondary objectives were to analyse the plasma cefepime concentrations and to define the threshold above which neurotoxicity occurs. METHODS: In this single-centre retrospective cohort study, all adult patients who underwent at least one cefepime therapeutic drug monitoring (TDM) and were treated with CI of 4 g/day between January 2017 and June 2019 were included. Neurotoxicity was evaluated according to a strict definition and was correlated with steady-state concentration at the time of toxicity presentation. RESULTS: Ninety-eight patients with 201 cefepime TDM studies were included, with an incidence of neurotoxicity of 14.3% (14/98). Patients with neurotoxicity had more often underlying brain disease (35.7% (5/14) vs 11.9% (10/84), p = 0.030)) and higher steady-state concentrations (mean ± standard deviation 71.8 ± 32.9 mg/L vs 49.6 ± 30.6, p = 0.036) than the others. A receiver operating characteristic curve analysis yielded a cefepime steady-state concentration of 63.2 mg/L as the best cut-off point between patients with or without neurotoxicity. A mean steady-state concentration of 46.4 mg/L was achieved if the dosages of cefepime were adapted to renal function which was under our threshold concentration but above our highest pharmacokinetic/pharmacodynamic target of 32-40 mg/L. CONCLUSIONS: Our results suggest that 4 g/day of cefepime adapted to renal function and infused over 24 h is a trade-off for the risk/benefit ratio, when used empirically.

[Influence of clinical and pathological factors on lymph node harvesting in surgical specimens of colorectal cancer]. / Facteurs anatomo-cliniques influençant la collecte ganglionnaire dans les pièces de résection chirurgicale pour cancer colorectal.

In colorectal cancer staging, pathologic lymph node analysis is a crucial information for the clinician and must be performed with a maximal level of accuracy. Therefore, the surgical sample analysis needs harvesting of as many lymph nodes as possible from the mesentery. In this study, we analysed the influence of a series of clinical and pathological factors which could influence lymph node harvesting. A total of 239 patients were included in our study. The factors with a statistically significant influence on lymph node collection (pinferior to0.05) were the age, gender of the patient, size of the primitive neoplasm, size of the surgical specimen, expertise of the surgeon and the pathology department. The presence of a radiochimiotherapy did not have any influence on the lymph node collection. This study highlights the importance of lymph node harvesting in colorectal surgical specimens of colo-rectal cancers.

Dans la stadification de l'adénocarcinome colorectal, le statut ganglionnaire anatomopathologique constitue une information capitale pour le clinicien et doit être défini avec un maximum d'exactitude. L'analyse de la pièce de résection chirurgicale requiert la collecte au sein du méso du plus grand nombre possible de ganglions lymphatiques. Dans cette étude, nous avons analysé une série de facteurs anatomo-cliniques pouvant influencer la collecte ganglionnaire. Un total de 239 patients a été inclus dans notre étude. Les facteurs avec une influence statistiquement significative sur la collecte ganglionnaire (p inf�rieur a 0,05) ont été l'âge et le sexe du patient, la taille de la tumeur primitive, la taille de la pièce d'exérèse, le degré d'activité du chirurgien et le laboratoire d'anatomie pathologique. La présence ou non d'une radiochimiothérapie néo-adjuvante n'a pas eu d'impact sur le nombre de ganglions prélevés. Cette étude souligne l'importance de la collecte ganglionnaire au sein des pièces de résection chirurgicale d'un cancer colo-rectal.

[Emergency department utilization by HIV-positive adults in a Belgian setting]. / Etude des motifs d'admission au service des Urgences d'une cohorte de patients infectés par le VIH suivis au CHU de Liège.

The use of the emergency department (ED) by human immunodeficiency virus (HIV)-infected adults undergoes an evolution following the introduction of antiretroviral therapy (ART). Improving our knowledge about ED use characteristics will contribute to a correct diagnosis and therapeutic approach in this patient group, at the moment they are discharged from the ED. We conducted a one-year retrospective study on characteristics of ED use involving 1026 patients living with HIV. The majority of them was treated with antiretroviral therapy (95 %) and had a viral load lower than 50 copies (73.6 %). Among them, 117 patients (11.8 %) were admitted at least once to the ED. The most common ED discharge diagnoses were related to trauma (30 %). This study shows that the great majority of diagnoses were not related to infectious diseases (6.3 %, of which half were HIV-related). One hypothesis to explain these results would be that HIV-positive adults in this study had excellent antiretroviral coverage and were well controlled in terms of HIV.

L'utilisation du département des urgences (DU) par les adultes infectés par le virus de l'immunodéficience humaine (VIH) évolue suite à l'instauration des traitements antirétroviraux (TAR). Nous avons besoin d'améliorer nos connaissances à ce sujet et d'en savoir plus sur le diagnostic de ces patients lorsqu'ils quittent le service d'urgence. Nous avons réalisé une étude rétrospective sur une durée d'un an et qui s'intéresse aux caractéristiques de l'utilisation du DU par 1.026 patients vivant avec le VIH. La majorité d'entre eux était sous traitement anti-rétroviral (95 %) et avait une charge virale inférieure à 50 copies (73,6 %). Parmi eux, 117 (11,8 %) se sont présentés au moins une fois au DU. Les principaux motifs d'admission étaient d'ordre traumatologique (30 %). Cette étude montre que la grande majorité des motifs d'admission au DU des patients vivant avec le VIH n'était pas en rapport avec des pathologies infectieuses (seulement 6,3 %, dont la moitié directement liées au VIH). Une hypothèse pour expliquer ces résultats serait que les patients étudiés bénéficiaient d'une excellente couverture anti-rétrovirale et étaient bien contrôlés en termes de VIH.

Transport of dissolved organic matter in Boom Clay: Size effects.

A coupled experimental-modelling approach was developed to evaluate the effects of molecular weight (MW) of dissolved organic matter (DOM) on its transport through intact Boom Clay (BC) samples. Natural DOM was sampled in-situ in the BC layer. Transport was investigated with percolation experiments on 1.5cm BC samples by measuring the outflow MW distribution (MWD) by size exclusion chromatography (SEC). A one-dimensional reactive transport model was developed to account for retardation, diffusion and entrapment (attachment and/or straining) of DOM. These parameters were determined along the MWD by implementing a discretisation of DOM into several MW points and modelling the breakthrough of each point. The pore throat diameter of BC was determined as 6.6-7.6nm. Below this critical size, transport of DOM is MW dependent and two major types of transport were identified. Below MW of 2kDa, DOM was neither strongly trapped nor strongly retarded. This fraction had an averaged capacity factor of 1.19±0.24 and an apparent dispersion coefficient ranging from 7.5×10-11 to 1.7× 10-11m2/s with increasing MW. DOM with MW>2kDa was affected by both retardation and straining that increased significantly with increasing MW while apparent dispersion coefficients decreased. Values ranging from 1.36 to 19.6 were determined for the capacity factor and 3.2×10-11 to 1.0×10-11m2/s for the apparent dispersion coefficient for species with 2.2kDa

Quality of documentation on antibiotic therapy in medical records: evaluation of combined interventions in a teaching hospital by repeated point prevalence survey.

This study aimed to improve the quality of documentation on antibiotic therapy in the computerized medical records of inpatients. A prospective, uncontrolled, interrupted time series (ITS) study was conducted by repeated point prevalence survey (PPS) to audit the quality of documentation on antibiotic therapy in the medical records before and after a combined intervention strategy (implementation of guidelines, distribution of educational materials, educational outreach visits, group educational interactive sessions) from the antimicrobial stewardship team (AST) in the academic teaching hospital (CHU) of Liège, Belgium. The primary outcome measure was the documentation rate on three quality indicators in the computerized medical records: (1) indication for treatment, (2) antibiotics prescribed, and (3) duration or review date. Segmented regression analysis was used to analyze the ITS. The medical records of 2306 patients receiving antibiotics for an infection (1177 in the pre-intervention period and 1129 in the post-intervention period) were analyzed. A significant increase in mean percentages in the post-intervention period was observed as compared with the pre-intervention period for the three quality indicators (indication documented 83.4 ± 10.4 % vs. 90.3 ± 6.6 %, p = 0.0013; antibiotics documented 87.9 ± 9.0 % vs. 95.6 ± 5.1 %, p < 0.0001; and duration or review date documented 31.9 ± 15.4 % vs. 67.7 ± 15.2 %, p < 0.0001). The study demonstrated the successful implementation of a combined intervention strategy from the AST. This strategy was associated with significant changes in the documentation rate in the computerized medical records for the three quality indicators.

Localized Piezoelectric Alveolar Decortication for Orthodontic Treatment in Adults: A Randomized Controlled Trial.

This randomized controlled trial aimed to evaluate the benefits and clinical outcomes of piezocision, which is a minimally invasive approach to corticotomy that is used in orthodontic treatments. Twenty-four adult patients presenting with mild overcrowdings were randomly allocated to either a control group that was treated with conventional orthodontics or a test group that received piezo-assisted orthodontics. The piezocisions were performed 1 wk week after the placement of the orthodontic appliances. Neither grafting material nor sutures were used. All patients were followed every 2 wk, and archwires were changed only when they were no longer active. The periods required for the completion of the overall orthodontic treatments were calculated, and the periodontal parameters were evaluated at baseline and at the end of the orthodontic treatment. Patient-centered outcomes were assessed with a visual analog scale; analgesic use following the procedures was also recorded. The patient characteristics were similar between the 2 groups. The overall treatment time was significantly reduced by 43% in the piezocision group as compared with the control group. In both groups, periodontal parameters (i.e., recession depth, pocket depth, plaque index, and papilla bleeding index) remained unchanged between the baseline and treatment completion time points. No increase in root resorption was observed in either group. Scars were observed in 50% of the patients in the piezocision group. Analgesic consumption was similar following orthodontic appliance placement and piezocision surgery. Patient satisfaction was significantly better in the piezocision group than in the control group. In these conditions, the piezocision technique seemed to be effective in accelerating orthodontic tooth movement. No gingival recessions were observed. The risk of residual scars might limit the indications for piezocision in patients with a high smile line (ClinicalTrials.gov NCT02590835).

Lanthanide-based laser-induced phosphorescence for spray diagnostics.

Laser-induced phosphorescence (LIP) is a relatively recent and versatile development for studying flow dynamics. This work investigates certain lanthanide-based molecular complexes for their use in LIP for high-speed sprays. Lanthanide complexes in solutions have been shown to possess long phosphorescence lifetimes (∼1-2 ms) and to emit light in the visible wavelength range. In particular, europium and terbium complexes are investigated using fluorescence/phosphorescence spectrometry, showing that europium-thenoyltrifluoracetone-trioctylphosphineoxide (Eu-TTA-TOPO) can be easily and efficiently excited using a standard frequency-tripled Nd:YAG laser. The emitted spectrum, with maximum intensity at a wavelength of 614 nm, is shown not to vary strongly with temperature (293-383 K). The decay constant of the phosphorescence, while independent of ambient pressure, decreases by approximately 12 µs/K between 323 and 373 K, with the base level of the decay constant dependent on the used solvent. The complex does not luminesce in the gas or solid state, meaning only the liquid phase is visualized, even in an evaporating spray. By using an internally excited spray containing the phosphorescent complex, the effect of vaporization is shown through the decrease in measured intensity over the length of the spray, together with droplet size measurements using interferometric particle imaging. This study shows that LIP, using the Eu-TTA-TOPO complex, can be used with different solvents, including diesel surrogates. Furthermore, it can be easily handled and used in sprays to investigate spray breakup and evaporation.

Alteration of the molecular-size-distribution of Boom Clay dissolved organic matter induced by Na(+) and Ca(2).

In porous media, the extent of dissolved organic matter (DOM)-facilitated contaminant transport depends on the concentration, conformation and the size of the dissolved organic species. Yet, these parameters are highly sensitive to the ionic strength (IS) and the ionic composition of the solution. Boom Clay (BC) which is considered in Belgium as a potential host rock for nuclear waste disposal contains polydisperse DOM that might associate with radionuclide and increase their mobility. To get more insight into the effect of IS on DOM structure and into its impact on the solid/solution partitioning of OM in BC is essential for safety assessment. In a first set, we investigated the influence of NaCl and CaCl2 content on the concentration, the MW distribution and UV spectral parameters of DOM collected from BC. With an increase in IS two main mechanisms were identified: a compaction and/or dissociation of the DOM molecules and an aggregation. We showed that the sensitivity of the DOM species to these two mechanisms was size/MW dependent and that the presence of Ca(2+) promotes the aggregation. The largest species are more prone to aggregation which at the extreme leads to their transfer to particulate OM. On the contrary, small DOM species hardly aggregate but compact or dissociate with an increase of IS. These observations were confirmed in the second experimental set in which we followed the release of DOM from BC rock in various electrolytes. The increase of IS and multivalent cations content reduces the amount, the degree of aromaticity and the MW of DOM released from BC which limit the extent of DOM-facilitated contaminant transport in BC.

Treatment of boundary conditions in through-diffusion: A case study of (85)Sr(2+) diffusion in compacted illite.

Valuable techniques to measure effective diffusion coefficients in porous media are an indispensable prerequisite for a proper understanding of the migration of chemical-toxic and radioactive micropollutants in the subsurface and geosphere. The present article discusses possible pitfalls and difficulties in the classical through-diffusion technique applied to situations where large diffusive fluxes of cations in compacted clay minerals or clay rocks occur. The results obtained from a benchmark study, in which the diffusion of (85)Sr(2+) tracer in compacted illite has been studied using different experimental techniques, are presented. It is shown that these techniques may yield valuable results provided that an appropriate model is used for numerical simulations. It is further shown that effective diffusion coefficients may be systematically underestimated when the concentration at the downstream boundary is not taken adequately into account in modelling, even for very low concentrations. A criterion is derived for quasi steady-state situations, by which it can be decided whether the simplifying assumption of a zero-concentration at the downstream boundary in through-diffusion is justified or not. The application of the criterion requires, however, knowledge of the effective diffusion coefficient of the clay sample. Such knowledge is often absent or only approximately available during the planning phase of a diffusion experiment.

Uptake of uranium(VI) by pyrite under boom clay conditions: influence of dissolved organic carbon.

The uptake of uranium(VI) by natural pyrite, FeS(2), was studied under conditions relevant for geological disposal of radioactive waste (anoxic atmosphere, approximately 0.014 mol.L(-1) NaHCO(3) electrolyte) with special emphasis on the role of dissolved organic matter. Solution analysis of batch experiments with different initial concentrations of uranium(VI) (10(-8)-10(-4) mol.L(-1)) was combined with X-ray absorption spectroscopy on the solid phase to elucidate the speciation of uranium in these systems and to gain insight into the major reaction mechanisms between uranium and pyrite. The results showed that, under the conditions of the experiments, uranium(VI) was at least partly reduced to a UO(2)(s)-like precipitate, although the predominant valence state of uranium in solution was likely uranium(VI). All observations indicate that the uranium solid-liquid distribution is governed by both reduction and adsorption processes. No significant amounts of uranium colloids (either intrinsic UO(2) colloids or complexes with natural organic matter) were found in any of the samples. The presence of dissolved organic matter did, however, increase the final uranium solution concentration and decrease the fraction of uranium(IV) found in the solid phase.

Clinical impact of a PCR assay for identification of Staphylococcus aureus and determination of methicillin resistance directly from blood cultures.

We evaluated the clinical usefulness of a PCR assay that discriminates Staphylococcus aureus from coagulase-negative staphylococci and detects methicillin resistance on blood cultures by measuring the adaptation of antimicrobial therapy based on the PCR results. Only 7 of 28 patients (25%) benefited from a modification of antibiotic therapy based on the PCR results, since empirical therapy was appropriate in a majority of cases.

Evaluation of a triplex PCR assay to discriminate Staphylococcus aureus from coagulase-negative Staphylococci and determine methicillin resistance from blood cultures.

A triplex PCR targeting the 16S rRNA, mecA, and nuc genes was developed for identification of staphylococci and detection of methicillin resistance. After validation of the assay with a collection of strains of staphylococci and enterococci (n = 169), the assay was evaluated with cultures of blood with gram-positive cocci from 40 patients. Accurate results were obtained for 59 (98%) of 61 cultures within 6 h of growth detection.

National epidemiologic surveys of Enterobacter aerogenes in Belgian hospitals from 1996 to 1998.

Two national surveys were conducted to describe the incidence and prevalence of Enterobacter aerogenes in 21 Belgian hospitals in 1996 and 1997 and to characterize the genotypic diversity and the antimicrobial resistance profiles of clinical strains of E. aerogenes isolated from hospitalized patients in Belgium in 1997 and 1998. Twenty-nine hospitals collected 10 isolates of E. aerogenes, which were typed by arbitrarily primed PCR (AP-PCR) using two primers and pulsed-field gel electrophoresis. MICs of 10 antimicrobial agents were determined by the agar dilution method. Beta-lactamases were detected by the double-disk diffusion test and characterized by isoelectric point. The median incidence of E. aerogenes colonization or infection increased from 3.3 per 1,000 admissions in 1996 to 4.2 per 1000 admissions in the first half of 1997 (P < 0.01). E. aerogenes strains (n = 260) clustered in 25 AP-PCR types. Two major types, BE1 and BE2, included 36 and 38% of strains and were found in 21 and 25 hospitals, respectively. The BE1 type was indistinguishable from a previously described epidemic strain in France. Half of the strains produced an extended-spectrum beta-lactamase, either TEM-24 (in 86% of the strains) or TEM-3 (in 14% of the strains). Over 75% of the isolates were resistant to ceftazidime, piperacillin-tazobactam, and ciprofloxacin. Over 90% of the strains were susceptible to cefepime, carbapenems, and aminoglycosides. In conclusion, these data suggest a nationwide dissemination of two epidemic multiresistant E. aerogenes strains in Belgian hospitals. TEM-24 beta-lactamase was frequently harbored by one of these epidemic strains, which appeared to be genotypically related to a TEM-24-producing epidemic strain from France, suggesting international dissemination.

Rapid identification of clinically relevant Legionella spp. by analysis of transfer DNA intergenic spacer length polymorphism.

Analysis of PCR-amplified transfer DNA (tDNA) intergenic spacers was evaluated as a rapid method for identification to the species level of 18 species of Legionella known as human pathogens. Type strains (n = 19), reference strains (n = 16), environmental strains (n = 31), and clinical strains (n = 32) were tested. PCR products using outwardly directed tDNA consensus primers were separated on polyacrylamide gels and analyzed with automated laser fluorescence. Test results were obtained in 8 h starting with 72-h-old bacterial growth on solid medium. Species-specific patterns were obtained for all 18 Legionella species tested: Legionella anisa, L. bozemanii serogroups 1 and 2, L. cincinnatiensis, L. dumoffii, L. feeleii serogroups 1 and 2, L. gormanii, L. hackeliae serogroups 1 and 2, L. jordanis, L. lansingensis, L. longbeachae serogroups 1 and 2, L. lytica, L. maceachernii, L. micdadei, L. oakridgensis, L. parisiensis, L. pneumophila serogroups 1 to 14, L. sainthelensi serogroup 2, L. tucsonensis, and L. wadsworthii. Computer-assisted matching of tDNA-intergenic length polymorphism (ILP) patterns identified all 63 environmental and clinical strains to the species level and to serogroup for some strains. tDNA-ILP analysis is proposed as a routinely applicable method which allows rapid identification of environmental and clinical isolates of Legionella spp. associated with legionellosis.

Rapid and accurate identification of Staphylococcus species by tRNA intergenic spacer length polymorphism analysis.

PCR-amplified tRNA gene (tDNA) intergenic spacer length polymorphism (tDNA-ILP) was analyzed for its ability to identify to the species level type strains (n = 18) and clinical isolates (n = 163) of staphylococci. Amplified products obtained by PCR with outwardly directed consensus tDNA primers were separated by agarose and polyacrylamide gel electrophoreses. The results were compared with those obtained by biochemical identification and ribotyping. Each type strain presented a specific tDNA-ILP pattern. PCR with fluorescent primers allowed for the detection of labelled DNA fragments on polyacrylamide gels by using an automated laser fluorescence sequencer and provided enhanced pattern resolution in comparison with that by analysis on agarose gels. tDNA patterns indistinguishable from those of the type strains were produced by clinical isolates of all tested species except for some isolates of S. aureus (n = 3) and S. haemolyticus (n = 1), which showed variant patterns. Strains of S. saprophyticus and S. xylosus showed very closely related profiles, and S. cohnii subspecies were indistinguishable. The identities obtained by tDNA-ILP analysis agreed with those obtained by the biochemical method to the species level for 99% (162 of 163) of the strains tested and to the subspecies level for 96% (156 of 163) of the strains tested. These results indicate that fluorescence-labelled PCR analysis of tDNA-ILP provides an accurate and rapid molecular method for the identification of human staphylococci.

Molecular epidemiology of an outbreak of multidrug-resistant Enterobacter aerogenes infections and in vivo emergence of imipenem resistance.

Molecular typing was used to investigate an outbreak of infection caused by multidrug-resistant Enterobacter aerogenes (MREA) susceptible only to gentamicin and imipenem in an intensive care unit (ICU). Over a 9-month period, ciprofloxacin-resistant E. aerogenes isolates were isolated from 34 patients, or 4.1% of ICU admissions, compared with a baseline rate of 0.1% in the previous period (P < 0.001). Infection developed in 15 (44%) patients. In vivo emergence of imipenem resistance (MIC, 32 micrograms/ml) of organisms causing deep-seated infection was observed in two (13%) of these patients following prolonged therapy with imipenem and gentamicin. Arbitrarily primed PCR (AP-PCR) analysis with ERIC1R and ERIC2 primers and pulsed-field gel electrophoresis (PFGE) analysis of XbaI macrorestriction patterns concordantly showed that outbreak-associated MREA isolates were clonally related and distinct from epidemiologically unrelated strains. AP-PCR and PFGE showed discrimination indices of 0.88 and 0.98, respectively. Space-time clustering of cases within units suggests that the epidemic-related MREA isolates were transmitted on the hands of the health care personnel. A case-control study and repeated environmental culture surveys failed to identify a common source or procedure associated with transmission. In spite of the early implementation of isolation measures, the incidence of MREA colonization remained stable until all colonized patients were discharged. This study confirms the usefulness of AP-PCR and PFGE analyses for the epidemiological study of E. aerogenes and underscores the difficulty of controlling the spread of multiresistant clones of this organism in the ICU setting. The emergence of imipenem resistance represents a threat because virtually no therapeutic option is available for such strains.