Abstract
BackgroundThe risk of acquisition of antibiotic resistant-bacteria during or shortly after antibiotic therapy is still unclear and it is often confounded by scarce data on antibiotic usage.Primary objective of the study is to compare rates of acquisition of methicillin-resistant Staphylococcus aureus and extended spectrum beta-lactamase-producing Enterobacteriaceae in hospitalised patients, after starting antibiotic therapy.Methods/DesignThe study, running in three European hospitals, is a multicenter, prospective, longitudinal, observational cohort study funded from the European Community's Seventh Framework Programme [FP7/2007-2013] within the project 'Impact of Specific Antibiotic Therapies on the prevalence of hUman host ResistaNt bacteria' (acronym SATURN). Nasal and rectal screening for methicillin-resistant Staphylococcus aureus and extended spectrum beta-lactamase-producing Enterobacteriaceae will be obtained at hospital admission, discharge, at antibiotic start (t0, within one hour) and at the following intervals: day 3 (t1), 7 (t2), 15 (t3), and 30 (t4). Two nested case-control studies will be performed. The objective of the first study will be to define individual level of risk related to specific antibiotics. Patients acquiring methicillin-resistant Staphylococcus aureus and extended spectrum beta-lactamase-producing Enterobacteriaceae (cases) will be compared with patients not acquiring antibiotic-resistant strains after starting antibiotic therapy (controls; ratio 1:4). To define the impact of antibiotics on new acquisition of target antibiotic-resistant bacteria, a second nested case-control study will be done (ratio 1:4). Control group will be selected among patients not receiving antibiotics, admitted in the same ward on the day of the corresponding case, with negative cultures at admission. Epidemiological, clinical and microbiological data will be prospective collected.DiscussionThe rationale of this study is to better understand the impact of antibiotic use on acquisition, selection and transmission of antimicrobial resistant-bacteria in European hospitals.Trial registrationClinicalTrials.gov NCT01208519.
Highlights
The risk of acquisition of antibiotic resistant-bacteria during or shortly after antibiotic therapy is still unclear and it is often confounded by scarce data on antibiotic usage
Selective pressure exerted by antibiotics plays a central role on the acquisition, selection, persistence and transmission of resistant pathogens which may include the following effects: (1) eradication of the susceptible skin and gut flora will increase the likelihood of acquisition of antibioticresistant organisms, especially in settings with endemic resistance; (2) antibiotics select for pre-existing antibioticresistant bacteria (ARB) in carriers and enhance the likelihood of spread; (3) antibiotic selection pressure may transform low-level carriers to high-level spreaders; (4) antibiotics active against antibiotic-susceptible bacteria may convert carriers of susceptible bacteria to non-carriers, indirectly promoting acquisition and spread of ARB; (5) antibiotic exposure may increase the risk of endogenous infection with ARB related to changes in colonisation resistance and bacterial virulence at the individual host level [4]
A meta-analysis that included 76 studies for a total of 24,230 patients documented that the risk of acquiring methicillin-resistant Staphylococcus aureus (MRSA) was increased by 1.8-fold in patients who had taken antibiotics
Summary
The control of nosocomial antibioticresistant infections is still a permanent and unresolved issue in healthcare institutions worldwide facing increased morbidity, mortality and hospital costs [1,2,3]. A multicentre prospective cohort study conducted in several Italian hospitals showed that 5% of patients were newly colonised by ARB including MRSA in nasal samples, after starting antibiotic therapy Nine percent of those patients developed an infection by the same strain over the 30-day follow-up. Several outcomes will be obtained at the end of the study (December 2014, expected): the rate of acquisition of target ARB by 1,000 antibiotic-days according to different classes of antibiotics, duration of therapy, and antibiotic combinations (monotherapy versus combinations); risk factors associated with new colonisation by target ARB; and risks for nosocomial infections due to target ARB after a cycle of antibiotic therapy adjusted by length of hospitalisation and ward colonisation pressure. We do expect that SATURN project results will have a direct impact on clinical practice, improving the appropriateness of antibiotic prescribing policy, the prevention of antibiotic-resistant infections and the heightener of patients’ quality care
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