Antibiotic resistance in children with urinary tract infections has reached high levels, according to research from Imperial College London.

The study, published in The BMJ, warns that some commonly used antibiotics - so called first-line treatments - could soon be rendered ineffective.

The research, which was carried out in conjunction with the University of Bristol, also suggests children can harbour antibiotic resistant bacteria for up to six months after treatment. This means an antibiotic may not work for a second time if prescribed twice within a six month window.

Dr Ceire Costelloe, senior author of the study from the Department of Medicine at Imperial said: “Children are prescribed more antibiotics than any other age group – and this is one of the first global studies to look at antibiotic resistance in urinary tract infections in children. Our results suggests prevalence of E coli bacteria resistant to antibiotics is high – and this resistance is particularly high in the under-five age group. This suggests many commonly prescribed antibiotics for these urinary tract infections – such as ampicillin, co-trimoxazole and trimethoprim – may no longer be suitable as first line treatment options.”

In the study, which was funded by the National Institute for Health Research, the team pooled the findings of 58 studies which looked at antibiotic resistance in urinary tract infections caused by E coli. These studies were from 26 countries, and involved over 77,000 E coli samples.

The highest amount of resistance was seen to ampicillin, the most commonly prescribed antibiotic for urinary tract infections caused by E coli.

Dr Costelloe adds:  “Our study suggests policy makers and medical staff need to carefully consider the type of antibiotic they are prescribing to patients. Although antibiotics are crucial to tackling infections in children – and should always be taken if prescribed - European and U.S guidelines recommend that if resistance to a particular type of antibiotic is above 20 per cent, this particular medication should no longer be used as first line treatment. However, we found that resistance exceeds this in most areas of the globe. This needs urgent attention, to prevent a scenario where antibiotics are no longer effective.”

"Global prevalence of antibiotic resistance in paediatric urinary tract infections caused by Escherichia coli and association with routine use of antibiotics in primary care: systematic review and meta-analysis" by Ashley Bryce, Alastair D Hay, Isabel F Lane, Hannah V Thornton, Mandy Wootton and Céire Costelloe is published in The BMJ