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Antimicrobial Agents and Chemotherapy, October 2009, p. 4264-4269, Vol. 53, No. 10
0066-4804/09/$08.00+0 doi:10.1128/AAC.00431-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Antibiotic Usage and Risk of Colonization and Infection with Antibiotic-Resistant Bacteria: a Hospital Population-Based Study
Evelina Tacconelli,1*
Giulia De Angelis,1
Maria Adriana Cataldo,1
Elisabetta Mantengoli,2
Teresa Spanu,1
Angelo Pan,3
Giampaolo Corti,4
Anna Radice,5
Lucia Stolzuoli,2
Spinello Antinori,5
Franco Paradisi,4
Giampiero Carosi,3
Roberto Bernabei,1
Massimo Antonelli,1
Giovanni Fadda,1
Gian Maria Rossolini,2 and
Roberto Cauda1
Departments of Infectious Diseases, Microbiology, Gerontology and Intensive Care and Anesthesiology, Università Cattolica Sacro Cuore, Rome, Italy,1 Departments of Molecular Biology, Section of Microbiology, and Infectious Diseases, University of Siena, Siena, Italy,2 Institute of Tropical and Infectious Diseases, Spedali Civili, University of Brescia, Brescia, Italy,3 Infectious Disease Unit, University of Florence School of Medicine, Florence, Italy,4 Department of Clinical Sciences L. Sacco, Section of Infectious Diseases and Immunopathology, University of Milan, Milan, Italy5
Received 30 March 2009/ Returned for modification 26 June 2009/ Accepted 1 August 2009
Accurate assessment of risk factors for nosocomial acquisition of colonization by antibiotic-resistant bacteria (ARB) is often confounded by scarce data on antibiotic use. A 12-month, nested, multicenter cohort study was conducted. Target ARB were methicillin (meticillin)-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and ciprofloxacin-resistant Pseudomonas aeruginosa (CR-PA). Nares and rectal swabs were obtained before and after starting antibiotics. Pulsed-field gel electrophoresis was done to define genetic relatedness of the strains. Primary outcomes were (i) the mean time, in days, for acquisition of target ARB colonization in patients previously not colonized; (ii) the rate of acquisition per 1,000 antibiotic-days according to different classes of antibiotics; (iii) the rate of infection caused by the same bacteria as those previously isolated in screening samples; and (iv) the risk factors for ARB acquisition. In total, 6,245 swabs from 864 inpatients were processed. The rate of acquisition was 3%, 2%, and 1% for MRSA, VRE, and CR-PA, respectively. The rate of acquisition of ARB per 1,000 antibiotic-days was 14 for carbapenems, 9 for glycopeptides, and 6 for broad-spectrum cephalosporins and quinolones. The highest rates of acquisition were observed for carbapenems in dialyzed and diabetic patients. Four risk factors were independently associated with acquisition of target ARB: use of carbapenems, age of >70 years, hospitalization for >16 days, and human immunodeficiency virus infection. During the 30-day follow-up, 4 among 42 patients newly colonized by ARB (9%) suffered from an infection due to the same bacteria as those isolated in a previous screening sample. Colonizing and infecting strains from single patients were genotypically identical. Identifying ARB colonization early during antibiotic therapy could target a high-risk hospitalized population that may benefit from intervention to decrease the risk of subsequent nosocomial infections.
* Corresponding author. Mailing address: Departments of Infectious Diseases, Università Cattolica del Sacro Cuore, Largo A. Gemelli 8, 00168, Rome, Italy. Phone: 39-06-30154945. Fax: 39-06-3054519. E-mail: etacconelli{at}rm.unicatt.it
Published ahead of print on 10 August 2009.
Antimicrobial Agents and Chemotherapy, October 2009, p. 4264-4269, Vol. 53, No. 10
0066-4804/09/$08.00+0 doi:10.1128/AAC.00431-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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