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


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


METHODS
General practices in Oxfordshire.


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


METHODS
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 microg/ml v 2.7 microg/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.


CONCLUSIONS
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.
Department of Primary Health Care, NIHR School of Primary Care Research, University of Oxford, Oxford OX3 7LF.
Angela
A
Chung
Rafael
R
Perera
Angela B
AB
Brueggemann
Abdel E
AE
Elamin
Anthony
A
Harnden
Richard
R
Mayon-White
Susan
S
Smith
Derrick W
DW
Crook
David
D
Mant
D000658:Amoxicillin / Q000627:therapeutic use; D000667:Ampicillin / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D005194:Family Practice / Q000706:statistics & numerical data*; D006192:Haemophilus Infections / Q000188:drug therapy*; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction / Q000379:methods; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000188:drug therapy*; D014759:Viral Envelope Proteins / Q000032:analysis; D018440:beta-Lactam Resistance
D000900:Anti-Bacterial Agents; D014759:Viral Envelope Proteins; D000667:Ampicillin; D000658:Amoxicillin