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Effect of antibiotic prescribing on antibiotic resistance in individual children in primary care: prospective cohort study

BMJ 2007; 335 doi: (Published 30 August 2007) Cite this as: BMJ 2007;335:429
  1. Angela Chung, clinical research fellow1,
  2. Rafael Perera, senior research fellow in statistics1,
  3. Angela B Brueggemann, infectious disease lecturer2,
  4. Abdel E Elamin, research student3,
  5. Anthony Harnden, university lecturer1,
  6. Richard Mayon-White, consultant epidemiologist1,
  7. Susan Smith, research group coordinator1,
  8. Derrick W Crook, consultant in infectious disease and microbiology3,
  9. David Mant, professor1
  1. 1Department of Primary Health Care, NIHR School of Primary Care Research, University of Oxford, Oxford OX3 7LF
  2. 2Department of Zoology, University of Oxford, Oxford OX1 3PS
  3. 3Nuffield Department of Clinical and Laboratory Science, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU
  1. Correspondence to: D Mant david.mant{at}
  • Accepted 24 June 2007


Objective To assess the effect of community prescribing of an antibiotic for acute respiratory infection on the prevalence of antibiotic resistant bacteria in an individual child.

Study design Observational cohort study with follow-up at two and 12 weeks.

Setting General practices in Oxfordshire.

Participants 119 children with acute respiratory tract infection, of whom 71 received a β lactam antibiotic.

Main outcome measures Antibiotic resistance was assessed by the geometric mean minimum inhibitory concentration (MIC) for ampicillin and presence of the ICEHin1056 resistance element in up to four isolates of Haemophilus species recovered from throat swabs at recruitment, two weeks, and 12 weeks.

Results Prescribing amoxicillin to a child in general practice more than triples the mean minimum inhibitory concentration for ampicillin (9.2 µg/ml v 2.7 µg/ml, P=0.005) and doubles the risk of isolation of Haemophilus isolates possessing homologues of ICEHin1056 (67% v 36%; relative risk 1.9, 95% confidence interval 1.2 to 2.9) two weeks later. Although this increase is transient (by 12 weeks ampicillin resistance had fallen close to baseline), it is in the context of recovery of the element from 35% of children with Haemophilus isolates at recruitment and from 83% (76% to 89%) at some point in the study.

Conclusion The short term effect of amoxicillin prescribed in primary care is transitory in the individual child but sufficient to sustain a high level of antibiotic resistance in the population.


  • Contributors: AC carried out this research as part of her DPhil thesis. RP supervised the statistical analysis. ABB supervised the laboratory work and microbiological analysis. AE undertook some of the gene sequencing as part of his DPhil thesis. AH and RM-W helped to design the project and draft the paper. SS oversaw the data management and assisted in the analysis. DC designed and oversaw the microbiology and supervised AC. DM obtained the funding, supervised AC, and drafted the paper. All authors commented on and contributed to various drafts of the paper and read and approved the final draft. AC and DM are guarantors.

  • Funding: Medical Research Council. Oxford University department of primary health care also receives programme funding for this area of research as part of the NIHR National School of Primary Care Research.

  • Competing interests: None declared.

  • Ethical approval: Central Oxford NHS research ethics committee.

    Provenance and peer review: Non-commissioned, externally peer reviewed.

  • Accepted 24 June 2007
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