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Impact of outpatient antibiotic use on carriage of ampicillin-resistant Escherichia coli

Samore, Matthew H
Tonnerre, Claude
Hannah, Elizabeth Lyon
Stoddard, Gregory J
Borotkanics, Robert J
Haddadin, Bassam
Published in Antimicrobial Agents and Chemotherapy. 2011, vol. 55, no. 3, p. 1135-41
Abstract Studies about the relationship between antibiotic consumption and carriage of antibiotic-resistant Escherichia coli in individual patients have yielded conflicting results. The goal of this study was to identify individual- and household-level factors associated with carriage of ampicillin (AMP)-resistant E. coli during consumption of a course of oral antibiotics. We enrolled outpatients and their families in a prospective household study of AMP-resistant or AMP-susceptible E. coli carriage. Two kinds of index patients were identified. Group 1 consisted of outpatients who were being initiated on a new antibiotic course at the time of a clinic visit, and group 2 consisted of outpatients not starting antibiotics. Each participant was asked to submit three stool swab samples (at baseline, week 1, and week 4) and to complete a questionnaire. Antimicrobial susceptibility testing was performed on each phenotypically distinct E. coli colony. The study included 149 group 1 households (total, 570 participants) and 38 group 2 households (total, 131 participants). AMP-resistant E. coli was recovered from 29% of stool samples. Observed associations with antibiotic exposure varied by drug class. Penicillins, which were the most frequently prescribed drug class, were associated with a modest increase in AMP-resistant E. coli carriage and a modest decrease in AMP-susceptible E. coli carriage. Neither change by itself was statistically significant. Macrolides were associated with reduced carriage of both AMP-resistant E. coli and AMP-susceptible E. coli (P < 0.05). Both AMP-resistant and AMP-susceptible E. coli demonstrated household clustering (P < 0.001). In summary, the overall effect of antibiotics on individual risk of carriage of AMP-resistant E. coli was small. However, even a modest alteration of the competitive balance between AMP-resistant and AMP-susceptible E. coli may promote population spread of resistant E. coli. Examining changes in both resistant and susceptible organisms in antibiotic-treated individuals and their close contacts improves understanding of antibiotic selection pressure.
Keywords AdolescentAmpicillin/therapeutic useAnti-Bacterial Agents/therapeutic useChildChild, PreschoolDrug Resistance, BacterialEscherichia coli/drug effects/pathogenicityEscherichia coli Infections/drug therapy/epidemiology/microbiologyFemaleHumansMaleMicrobial Sensitivity TestsOutpatients
PMID: 21115789
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Research group Groupe Harbarth Stephan (Staphylocoques dorés résistants à la méthicilline) (866)
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SAMORE, Matthew H et al. Impact of outpatient antibiotic use on carriage of ampicillin-resistant Escherichia coli. In: Antimicrobial Agents and Chemotherapy, 2011, vol. 55, n° 3, p. 1135-41. https://archive-ouverte.unige.ch/unige:25204

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Deposited on : 2013-01-09

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