Clinical Trial Details
— Status: Recruiting
Administrative data
| NCT number |
NCT00404625 |
| Other study ID # |
P1908 |
| Secondary ID |
|
| Status |
Recruiting |
| Phase |
N/A
|
| First received |
November 28, 2006 |
| Last updated |
November 28, 2006 |
| Start date |
October 2006 |
| Est. completion date |
November 2006 |
Study information
| Verified date |
November 2006 |
| Source |
University of Siena |
| Contact |
Gian Maria Rossolini, professore |
| Phone |
+39 0577 233455 |
| Email |
rossolini[@]unisi.it |
| Is FDA regulated |
No |
| Health authority |
Italy: Ethics Committee |
| Study type |
Observational
|
Clinical Trial Summary
To assess the molecular epidemiology, clinical impact, treatment outcome and risk factors
for infections caused by Enterobacteriaceae producing ESBLs in Italy in a large multicenter
observational survey.
SPECIFIC OBJECTIVES
1. To collect consecutive nonreplicate isolates of Enterobacteriaceae resistant to
expanded-spectrum cephalosporins from clinical specimens from inpatients and
outpatients.
2. To characterize the isolates for resistance phenotypes and for β-lactam resistance
mechanisms.
3. To investigate the clonality of isolates.
4. To analyse the epidemiology of various resistance mechanisms/resistant clones.
5. To collect clinical and epidemiological data for patients with infections caused by the
ESBL producers.
6. To analyse the epidemiology, risk factors and outcome for infections caused by ESBL
producers.
Description:
RESEARCH PLAN AND METHODOLOGY
Population All patients with infections (i.e. bacteremia, pneumonia, abdomen infections,
skin infections, and urinary tract infections) caused by ESBL-producing Enterobacteriaceae.
Exclusion criteria Children < 16 years
Trial design Multicenter prospective cohort study. Patients corresponding to the study
definition will be detected by daily inspection of microbiological databases by one
dedicated physician. Epidemiological variables will be detected for all patients at study
admission. To identify the risk factors for infections (i.e. bacteremia, pneumonia, abdomen
infections, skin infections, and urinary tract infections) caused by ESBL-producing
Enterobacteriaceae a case-control study will be performed. A case patient will be defined as
adult patient ( 16 years of age) who has an infection caused by ESBL-producing
Enterobacteriaceae according to the definitions of the Center for Diseases Control and
Prevention in Atlanta (CDC). In the Clinical Microbiology Laboratories, definition of ESBL
production by the Clinical Microbiology Laboratories will be according to the CLSI
guidelines (3), or to the BSAC guidelines (http://www.bsac.org.uk) for species other than
Klebsiella spp., E. coli and Proteus mirabilis. One control will be selected for each case.
Control will be chosen among all adult patients admitted to the same hospital during the
same period (within 30 days) and in whom ESBL-producing Enterobacteriaceae were not isolated
during their hospital stay. If more than one control will be available per case, patients
with the date and time of admission closest to the case will be chosen.
To identify the risk factors for mortality a second case-control study will be performed
comparing infected patients who died to infected patients who survived (evaluable in
patients with bacteremia, wound infections, pneumonia, and meningitis, only). This analysis
will be performed adjusting the results for inadequate empiric antimicrobial therapy and
site of infection (see following definitions).
Data collection Medical records of in-patient admissions and microbiology and pharmacy
databases will be reviewed. Data collected at the study enrollment will include: patient
demographics, transfer from another hospital, resident of a long term facility or nursing
home, previous hospitalization within one year, ambulatory status, requirement for chronic
hemodialysis, presence of a central venous catheter (CVC), and ICU stay and surgical
procedures in the 30 days prior to study inclusion. A composite score of co-morbid illnesses
will be derived using the Charlson score. The severity of illness at presentation will be
quantified using the criteria of McCabe and Jackson. Antibiotics administered during a
30-day period prior to study enrollment and for at least 48 hours will be recorded. For the
risk factors analysis, oral and intravenous antibiotic exposure will be analysed by
individual antibiotics and by classes, and will include penicillins, vancomycin,
cephalosporins, antibiotics with predominantly anaerobic activity (metronidazole and
clindamycin), aminoglycosides, quinolones, and carbapenems. Length of stay (LOS) after
infection diagnosis, management of infections, timing and type of antimicrobial therapy,
results of follow-up clinical cultures (if any), hematogenous complications and death will
be also extracted from medical records. Microbiology records will be also reviewed for
recovery of vancomycin resistant enterococci (VRE) or methicillin-resistant S. aureus (MRSA)
in the 12 months prior to the study enrollment. All patients with infections caused by
ESBL-producing Enterobacteriaceae will be followed up to hospital discharge or death.
Mortality will be defined as death occurring during the study hospitalization. Appropriate
antimicrobial therapy will be defined as the initiation of therapy with activity against the
ESBL-producing Enterobacteriaceae (according to the results of the antimicrobial
susceptibility pattern of the isolate) from the day before to 2 days after the initial
positive clinical culture result.
Outcomes Primary outcomes
1. Risk factors for the development of infections caused by ESBL producers bacteria;
2. Risk factors for inadequate initial antimicrobial therapy;
3. Overall mortality and 30-day mortality among patients receiving inadequate initial
antimicrobial therapy (evaluable in patients with bacteremia, abdominal infections and
pneumonia, only);
4. Variability by site of infection of overall mortality and 30-day mortality among
patients receiving inadequate initial antimicrobial therapy (evaluable in patients with
bacteremia, abdominal infections and pneumonia, only).
Secondary outcomes
1. Lenght of hospitalization;
2. Costs of inadequate initial therapy;
3. Days of defervescence.
Statistical analysis At the end of the study two different analysis will be performed: the
first one will consider patients with bacteremia, abdominal infections and pneumonia, and it
will be focused on mortality; the second analysis will consider all infected patients and it
will be focused on risk factor analysis and secondary outcomes.
Sample size justification Assumptions
Patients with bacteremia, pneumonia, abdomen infections, skin infections and urinary tract
infections (first analysis):
Mortality among patients with inadequate initial therapy: 25% Mortality among patients with
appropriate initial therapy: 13%
All included patients:
Percentage of bacteremia: 20% Percentage of pneumonia: 10% Percentage of abdomen infections:
15% Percentage of skin infections: 3% Percentage of urinary tract infections: 52%
Primary outcomes Risk factors for mortality Difference of mortality between controls
(inappropriate therapy) and cases (appropriate therapy): we anticipated a reduction from 25%
to 13%.
Secondary outcomes Difference of length of hospitalization between cases (appropriate
therapy) and controls (inappropriate therapy): we anticipated a decrease from 80% (length of
hospitalization < 15 days) to 40%.
Difference of defervescence between cases (appropriate therapy) and controls (inappropriate
therapy): we anticipated a decrease from 85% (defervescence < 3 days) to 30%.
Assuming that p1=p2, where p1 is the proportion in population 1 and p2 is the proportion in
population 2 and that alpha=0.05 (two-sided), power=0.80.
Required sample size for analysis of risk factors for mortality: 366 patients with
bacteremia, wound infections, pneumonia, and meningitis. To include 366 patients with the
above reported infections the total sample size is likely to be 813 patients infected with
ESBL-producing Enterobacteriaceae.
Microbiological analysis of bacterial strains
All ESBL-producing isolates obtained from patients included in the study at the Clinical
Microbiology Laboratories of each Clinical Center will be collected and subjected to further
investigation including:
- confirmation of the identification at the species level;
- determination of the antimicrobial resistance profile against a standard set of drugs;
- analysis of the ESBL determinants;
- analysis of clonal relationship between bacterial isolates of the same species. Results
of microbiological analysis will be used for correlation with clinical data to assess
the epidemiological and clinical impact of the ESBL-producing strains.
Experimental methodology
Confirmation of identification of the bacterial isolates at the species level will be
carried out by standard phenotypic methods (10). In case of ambiguity of results,
identification will be confirmed by 16S rDNA sequencing (16).
Antimicrobial susceptibility testing will be carried out by broth microdilution as
recommended by the CLSI (3), and categorical assignment will be carried out using the CLSI
breakpoints (3). The following agents will be included: ertapenem, imipenem, meropenem,
cefepime, ceftazidime, cefotaxime, piperacillin/tazobactam, amoxicillin/clavulanate,
ciprofloxacin, levofloxacin, gentamicin, amikacin.
The nature of the ESBL determinants will be investigated by molecular analysis using PCR and
sequencing, as described previously (9, 15). The presence of ESBL determinants of the TEM-,
SHV, CTX-M- and PER-type (i. e. those known to be circulating in Italy (9, 15)) will be
investigated. In case of negative results with the available probes, the ESBL phenotype will
be reconfirmed and, if positive, the nature of -lactamase deerminants will be studied by
means of: (i) analytical isoelectric focusing (IEF) on crude extracts using previously
described methods (14); (ii) DNA microarray technology, using a microarray for β-lactamase
genes that has been developed in our laboratory, which includes probes for uncommon ESBL
genes such as VEB, GES, BES, SFO, and TLA enzymes. In case of new ESBL genes undetected by
the above methods (an unlikely occurrence), In the case of production of ESBL but
unaccounted for by the presence of known resistance determinants, the resistance
determinants will be studied by means of a shotgun-cloning approach followed by mapping and
sequencing.
Clonal relatedness among isolates of the same species will be investigated by
high-throughput genotyping techniques such as RAPD (Random Amplified Polymorphic DNA) and/or
by AFLP (Amplified Fragment Length Polymorphism) analysis and/or REP PCR (19-21). In
selected isolates, the clonal relationships will be performed by macrorestriction analysis
of genomic DNA by pulsed-field gel electrophoresis (PFGE).
Plasmid analysis and investigation of resistance determinants to non β-lactam agents (by
molecular techniques) will be considered in selected cases, should these information be
relevant for correlation with clinical and epidemiological data.
