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Title
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Impact of amoxicillin therapy on resistance selection in patients with community-acquired lower respiratory tract infections : a randomized, placebo-controlled study
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Author
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Institution/Organisation
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GRACE Study Grp
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Abstract
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| To determine the effect of amoxicillin treatment on resistance selection in patients with community-acquired lower respiratory tract infections in a randomized, placebo-controlled trial. Patients were prescribed amoxicillin 1 g, three times daily (naEuroS=aEuroS52) or placebo (naEuroS=aEuroS50) for 7 days. Oropharyngeal swabs obtained before, within 48 h post-treatment and at 28-35 days were assessed for proportions of amoxicillin-resistant (ARS; amoxicillin MIC a parts per thousand yen2 mg/L) and -non-susceptible (ANS; MIC a parts per thousand yen0.5 mg/L) streptococci. Alterations in amoxicillin MICs and in penicillin-binding-proteins were also investigated. ITT and PP analyses were conducted. ARS and ANS proportions increased 11- and 2.5-fold, respectively, within 48 h post-amoxicillin treatment compared with placebo [ARS mean increase (MI) 9.46, 95% CI 5.57-13.35; ANS MI 39.87, 95% CI 30.96-48.78; PaEuroS < aEuroS0.0001 for both]. However, these differences were no longer significant at days 28-35 (ARS MI -3.06, 95% CI -7.34 to 1.21; ANS MI 4.91, 95% CI -4.79 to 14.62; PaEuroS > aEuroS0.1588). ARS/ANS were grouped by pbp mutations. Group 1 strains exhibited significantly lower amoxicillin resistance (mean MIC 2.8 mg/L, 95% CI 2.6-3.1) than group 2 (mean MIC 9.3 mg/L, 95% CI 8.1-10.5; PaEuroS < aEuroS0.0001). Group 2 strains predominated immediately post-treatment (61.07%) and although decreased by days 28-35 (30.71%), proportions remained higher than baseline (18.70%; PaEuroS=aEuroS0.0004). By utilizing oropharyngeal streptococci as model organisms this study provides the first prospective, experimental evidence that resistance selection in patients receiving amoxicillin is modest and short-lived, probably due to 'fitness costs' engendered by high-level resistance-conferring mutations. This evidence further supports European guidelines that recommend amoxicillin when an antibiotic is indicated for community-acquired lower respiratory tract infections. |
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Language
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English
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Source (journal)
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The journal of antimicrobial chemotherapy. - London, 1975, currens
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Publication
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London
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2016
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ISSN
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0305-7453
[print]
1460-2091
[online]
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DOI
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10.1093/JAC/DKW234
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Volume/pages
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71
:11
(2016)
, p. 3258-3267
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ISI
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000388005100033
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Full text (Publisher's DOI)
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Full text (open access)
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