European Prospective Cohort Study on Enterobacteriaceae Showing Resistance to Carbapenems
European Prospective Cohort Study on Enterobacteriaceae Showing Resistance to Carbapenems
Among antibiotic-resistant organisms, the Gram-negative bacteria are now the most important
 challenge because of the rapid worldwide spread of mechanisms conferring resistance to
 multiple drugs. The most recent and worrying problem is the emergence and spread of
 carbapenemases. Additionally, carbapenem-resistance is known to be very frequent among
 Acinetobacter baumannii isolates for many years. Overall, the therapeutic options available
 against carbapenem-resistant Enterobacteriaceae (CRE) and A. baumannii (CRAB) are very
 limited. The best available treatment (BAT) against CRE is unknown, which is a challenge for
 therapeutic decisions and also for the design of randomized trials with new drugs. The
 generic objectives of EURECA are to obtain high-quality observational data to inform the
 design of randomized controlled trials for complicated intraabdominal infections, pneumonia,
 complicated urinary tract infections and bloodstream infections due to Carbapenem-resistant
 Enterobacteriaceae (CRE) and carbapenem-resistant Acinetobater baumannii, and to provide
 cohort data that could eventually be used as historical controls for future comparisons with
 new drugs targeting CRE. This will be achieved by a prospective, multinational cohort study
 of patients with targeted infections due to CRE and CRAB, and by matched case-control-control
 studies.
HYPOTHESIS:

 H1: 5 independent predictors for cure and mortality can be identified, including active
 empirical therapy, early targeted optimized therapy and early source management if needed.

 H2: For pneumonia, cIAI (complicated intrabdominal infection) and BSI (bloodstream
 infection), combination therapy with two active drugs, one of them being (if available) an
 "active" beta-lactam (such as meropenem or imipenem if minimum inhibitory concentration [MIC]
 <16 mg/L, aztreonam if isolate is susceptible as in many metallo-beta-lactamase producers, or
 cephalosporin if isolate is susceptible as in some OXA-48 producers). For cUTI (complicated
 urinary tract infection), monotherapy with an "active" beta-lactam as above, colistin or an
 aminoglycoside (if active in vitro) is as effective as combination therapy.

 H3. Clinical cure rate at test of cure (TOC) will be 50% with BAT. H4: Specific carbapenemase
 types do not independently influence cure rate or mortality.

 H5: CRE infections caused by isolates showing a carbapenem MIC <16 mg/L are associated with
 higher probability of cure and lower mortality.

 H6: five significant independent predictors (risk factors) for CRE infection can be found.

 H7: the targeted infections due to CRE are significantly and independently associated with
 higher mortality, hospital stay and hospital costs than infections caused by
 carbapenem-susceptible Enterobacteriaceae (CSE) or than other diseases causing
 hospitalisation.

 SPECIFIC OBJECTIVES. O1. To characterise the features, clinical management and outcomes of
 hospitalised patients with cIAI, pneumonia, cUTI and BSI caused by CRE and CRAB.

 O1A. To provide cohorts of patients with the targeted infections caused by CRE and CRAB that
 would eventually be used as historical cohorts for comparison of efficacy and safety of newer
 drugs against these organisms.

 O1B. To identify the outcome predictors of patients with cIAI, pneumonia, cUTI and BSI caused
 by CRE and CRAB, with identification of the best alternative therapy (BAT).

 O1C. To exploratively investigate the importance of the specific carbapenemase and
 carbapenem-MIC in the outcome of CRE and CRAB infections.

 O2. To identify the risk factors for target infections caused by CRE to inform a more
 efficient design of future randomized clinical trials for these infections.

 O3. To assess the mortality, length of hospital stay and hospital costs associated with
 target infections caused by CRE.

 DESIGN AND STUDIES To answer the above objectives, a prospective, multinational, multicentre,
 observational and analytic project including 3 studies was design.

 Study 1. For the analysis of outcome predictors of CRE and CRAB infections (objective 1), a
 prospective cohort study of patients with the target infections due to CRE and CRAB will be
 performed.

 Study 2. For the analysis of risk factors for target infections caused by CRE (objective 2),
 a nested case-control-control will be performed. The first group of controls will be formed
 by matched patients with CSE infections, and the second groups of controls will be formed by
 admitted patients non-infected patients by CRE or CSE.

 Study 3. For the analysis of cost, outcome impact and length of stay associated to target
 infections caused by CRE (objective 3), a matched cohorts study will be performed. The
 cohorts will be formed by selected patients with infections due to CRE and the patients with
 infections due to CSE (identical to the CSE control group above). Additionally, a control
 group of admitted patients not infected by CRE or CSE will be studied (identical to the
 admitted control group above).

 SETTING This study will be performed in 50 European hospitals from Spain, Italy, Greece,
 Turkey, Serbia, Croatia, Montenegro, Kosovo, Albania, Bulgaria and Romania.

 STUDY PERIOD The recruitment period of the study is planned from February 2016 to June 2017.

 ENDPOINTS (MAIN OUTCOME VARIABLES) See below

 STUDY VARIABLES AND DEFINITIONS

 -  CRE: any isolate identified as an Enterobacteriaceae showing a minimum inhibitory
 concentration (MIC) ≥1 mg/L if using any dilution method and/or ≤22 mm if using a
 disc-diffusion method for imipenem or meropenem (10 µg disks); all others will be
 considered carbapenem susceptible (CSE), but meropenem and imipenem susceptible isolates
 showing resistance to ertapenem will be excluded.

 -  CRAB: Any isolate identified as Acinetobacter baumannii showing a minimum inhibitory
 concentration (MIC) ≥16 mg/L for imipenem or meropenem if using any dilution method
 and/or ≤17 mm for meropenem and/or ≤15 for imipenem if using a disc-diffusion method.

 -  Independent variables for Study 1: demographics, comorbidities in adults (Charlson's
 index), comorbidities in children (ARPEC PPS definitions), type of acquisition, systemic
 inflammatory response syndrome severity in adults, sepsis criteria in children, Pitt
 score, SOFA score, APACHE-II score, PIM2, invasive procedures, neutropenia,
 microbiological variables (poly or monomicrobial infection, carbapenemase producer,
 carbapenemases type, susceptibility profile, carbapenem MIC), clinical management
 (source control and support therapy), antimicrobial therapy.

 -  Independent variables for Study 2: demographics, length of hospital stay,
 epidemiological variables (travels, previous contact with persons colonised by CRE,
 previous hospitalization, nursing home or other long term-care facility residency,
 previous colonisation by CRE), comorbidities, acquisition type, SIRS severity in adults,
 sepsis in children, Pitt score, SOFA score, APACHE-II score, PIM2, invasive procedures,
 neutropenia, type of infection, microbiological variables, antibiotics received in the
 last 3 months.

 -  Independent variables for Study 3: all those included in Study 2.

 DATA COLLECTION AND FOLLOW-UP Data will be collected by trained local investigators. Patients
 will be followed for 30 days from day 0. Data prior to study entry will be collected by
 reviewing medical records or interviewing the patient, his/her family or the attending
 healthcare staff. After that, the patients will be followed prospectively. If the patients
 had been discharged before assessement, outcome must be assessed by an outpatient visit or
 phone call according to a pre-design questionnaire.

 MICROBIOLOGICAL STUDIES. All procedures will be performed locally using accepted, standard
 microbiological protocols. Isolates identified as CRE or CRAB according to above criteria
 will be locally studied for carbapenemase production using the CARBA-NP test. Susceptibility
 tests to key antimicrobial agents will be collected. Isolates preservation CRE and CRAB
 isolates will be preserved locally at least at -20ºC.

 SAFETY ASSESMENT No investigation drugs will be used in this study. Adverse event will be
 collected during follow-up as one variable of interest for analysis purposes.

 SAMPLE SIZE :

 -  Study 1 The sample size for the CRE and CRAB cohorts were calculated so that the cohorts
 may serve as 'historical' cohorts for future comparison with new drugs for CRE and CRAB.
 To do so, and because the estimates for the outcome variable of the new drug is unknown,
 we seek to estimate the clinical cure rate of BAT with 95% confidence interval and 8%
 precision. For an estimated cure rate of 50% based on data from previous studies, 151
 patients for each of the five types of infection are needed (due to CRE: cUTI,
 pneumonia, cIAI, and BSI; due to CRAB: BSI). However, because around 25% of patients
 will not receive BAT, we will need 201 patients per type of infection except for BSI due
 to A. baumannii, for which we will need 221 because some blood isolates identified as
 Acinetobacter spp in sites not specifying the species will not be A. baumannii (total,
 1025 patients). Such sample size will be enough also to investigate the best available
 therapy with the merged CRE cohorts.

 -  Study 2: The CRE case group will be formed by 248 patients with CRE infections selected
 from the study 1 cohort. Per each CRE case, one CSE control patient and 3 non-infected
 controls will be selected. Because of possible heterogeneity due to the different
 infection types, we have chosen to over sample by a ratio of 248/201*100%. The number of
 matched controls has been chosen to be four which is well known to well approximate the
 power of full cohort data.

 -  Study 3 The CRE, CSE and non-infected cohorts will be formed by the same patients as in
 Study 2. Therefore, the sample size rationale is as for Study 2, however with the
 refinement that the nested case control matching is now viewed as an exposure density
 sampling.

 STATISTICAL ANALYSIS

 -  Study 1. The outcomes associated with exposure to different variables will be compared;
 the targeted exposures will be empirical active antimicrobial therapy, early targeted
 optimized therapy, and early source control. Antimicrobial regimens will be analysed as
 empirical (administered before the susceptibility testing is available) and targeted
 (thereafter) therapy. The primary endpoint "mortality from any cause until day 30" will
 be analysed using survival methods (Kaplan-Meier, Cox regression). The other primary
 endpoint "clinical response at TOC" will be analysed as a dichotomous outcome,
 regression analyses will use the logistic regression model. The analysis of the
 secondary endpoints will be analogous. Microbiological response at TOC is a
 polychotomous outcome and will be analysed using multinomial logistic regression.
 Goodness of fit will be assessed throughout. Variable selection will be based on
 Akaike's information criterion.

 -  Study 2. Exposure to potential risk factors of patients will be compared between CRE
 cases and CSE controls, and between CRE cases and admitted controls. A stratified and
 weighted Cox analysis will be performed. Multilevel hospital data (local rate of CRE,
 antimicrobial consumption, infection control measures) will also be considered in the
 analyses above.

 -  Study 3. The impact of CRE infection on mortality, length of stay, cost, length of
 hospital and ICU stay, and length of mechanical ventilation of patients will be assessed
 by comparison with those of CSE infection and admitted patients. All time-to-event
 outcomes (for costs and extra hospital/ICU days see below) will be compared using
 survival techniques. Because the outcome infection due to CRE is subject to the
 competing risks of death in hospital w/o CRE infection and discharged alive from
 hospital with or without CRE infection, the analyses shall be supplemented by those of
 the competing outcomes. Goodness of fit will be assessed throughout. Extra hospital/ICU
 days will be estimated using the multistate approach of Beyersmann et al. Variable
 selection will be based on Akaike's information criterion. Goodness of fit will be
 assessed throughout.

 ETHICAL CONSIDERATIONS. Prior to initiation of a study site, approval will be sought from the
 appropriate regulatory agency and local Ethics Committees of Research or IRBs to conduct the
 study in accordance with regulatory requirements. This is an observational study and
 therefore no intervention is performed on behalf of the investigation. Management of all
 patients including all antibiotic regimens prescribed will be decided by the physician
 doctor/team in charge without any interference. The processing of the patients' personal data
 collected in this study shall comply with the Data Protection Act 1998 and with the European
 Directive on the Privacy of Data.

 MONITORING The study will be monitored for quality and consistency of data.
Selection criteria for CRE GROUPS and CRAB GROUP:

 Inclusion criteria (all must be fulfilled):

 -  Isolation of CRE or CRAB from a clinical sample (e.g., a sample obtained in the
 work-up of a patient with suspicion of infection; therefore, screening samples are not
 considered).

 -  The patient meets the criteria for any of the following infections (see definitions
 below): complicated urinary tract infection, pneumonia, intraabdominal infection or
 bloodstream infection (if the source of infection is any of the above, the patient
 will be included in both groups).

 -  Patient or his/her representative sign the inform consent if requested by the local
 Institutional Review Board (IRB).

 Patients in these groups will be included until the needed sample sizes are reached.

 Exclusion Criteria:

 -  The infection is considered to be polymicrobial according to standard microbiological
 interpretation of culture results (except for cIAI, in which polymicrobial infections
 are allowed).

 -  The patient was participating in a clinical trial that involved active treatment for
 the infections.

 -  The patient was previously included in the same cohort of this study for the same
 organism. A single episode of CRE or CRAB per patient can be included. Patients who
 suffer a CRE infection could later be included in the CRAB cohort if developing a CRAB
 infection and vice versa.

 -  Patients with do not resuscitate orders or with a life expectancy of <30 days.
 Selection criteria for CSE GROUP Inclusion criteria (all must be fulfilled)

 -  Isolation of CSE from a clinical sample (e.g., a sample obtained in the work-up of a
 patient with suspicion of infection; therefore, screening samples are not considered).

 -  The patient meets the criteria for any of the following infections (see definitions
 below): complicated urinary tract infection, pneumonia, intraabdominal infection or
 bloodstream infection (if the source of infection is any of the above, the patient
 will be included in both groups).

 -  The infection is the same as that of the index case; in case of BSI, the source of
 bacteraemia must be the same as the index case classified as follows: UTI, pneumonia,
 intraabdominal infection or any other.

 -  The type of acquisition is the same as for the index CRE case (nosocomial or
 community).

 -  The previous length of hospitalization before the infection onset is minus 1 up to
 minus 3 days the previous length of hospitalization before the CRE infection date in
 the CRE correspondent (up to minus 7 days if the CRE case occurred after 14 days of
 previous stay).

 -  The patient was admitted to the same type of service as the index case (medical,
 surgical, ICU, neonatal Unit, paediatric ICU, general paediatric wards).

 -  Patient or his/her representative sign the inform consent (if requested by local IRB).

 Patients in this group will be included until the needed sample size is reached.

 Exclusion criteria

 -  The infection is considered to be polymicrobial according to standard microbiological
 interpretation of culture results (except for cIAI, in which polymicrobial infections
 are allowed).

 -  Patient is participating in a clinical trial that involved active treatment for the
 infections at assessment.

 -  Patients with do not resuscitate orders or with a life expectancy of <30 days. The
 first patient found with all inclusion criteria and no exclusion criteria will be
 included.

 Selection criteria for ADMITTED CONTROL GROUP Inclusion criteria (all must be fulfilled)

 -  Patient is admitted in the same hospital ward where was admitted the index CRE.

 -  The previous length of hospitalization is at least one day less than the previous
 duration of hospitalisation of the correspondent CRE case when the CRE infection
 occurred.

 -  Patient or his/her representative sign the inform consent (if requested by local IRB).

 Patients in this group will be included until the needed sample size is reached.

 Exclusion criteria

 -  Patient was participating in a clinical trial that involved active treatment for the
 infections at assessment.

 -  Patients with do not resuscitate orders or with a life expectancy of <30 days.

 Because the search for CSE controls is more difficult, the search for admitted control
 patients can be started once a CSE control has been included; the first 3 patients with the
 above inclusion criteria and no exclusion criteria will be included.