BACKGROUND: Antimicrobial defined daily dose (DDD), has limitations for antimicrobial consumption measurement in paediatrics. An alternative DDD design applicable for children is proposed.
METHODS: Children (<16 years-old) from 10 Spanish hospitals during a 12-months period were included. Weight for age (50th percentile) was calculated for the median age of the cohort using standardized World Health Organization tables. DDD (g) for each antimicrobial was calculated by multiplying the obtained weight times the recommended dose (mg/kg) of the antimicrobial for the most common infectious indication.
RESULTS: A total of 40,575 children were included. Median age was 4.17 (IQR: 1.36-8.98) and 4.81 (IQR: 1.42-9.60) years for boys and girls, respectively. Mean weight for this age was 17.08kg. Standardized DDD for representative antimicrobials were calculated.
CONCLUSIONS: A useful method for antimicrobial DDD measurement in paediatrics has been proposed and should be validated in future studies for its use in paediatric antimicrobial stewardship programmes.

Evaluating the impact of antibiotic stewardship programs is challenging. There is evidence that they are effective in terms of reducing the consumption and cost of antibiotics, although establishing their impact on antimicrobial resistance (beyond restrictive policies in outbreaks caused by specific antimicrobial resistant organisms) and clinical outcomes is more difficult. Proper definitions of exposure and outcome variables, the use of advanced and appropriate statistical analyses and well-designed quasi-experimental studies would more accurately support the conclusions. Cluster randomized trials should be used whenever possible and appropriate, although the limitations of this approach should also be acknowledged. These issues are reviewed in this paper. We conclude that there are good research opportunities in the field of antibiotic stewardship.

In Spain, the inclusion of new antibiotics in hospital formularies is performed by the Infection Policy Committee or the Pharmacy and Therapeutic Committee, although now the decision is moving to a regional level. Criteria for the evaluation of new drugs include efficacy, safety and cost. For antimicrobial drugs evaluation it is necessary to consider local sensibility and impact in bacterial resistance to determinate the therapeutic positioning. There is compelling evidence that the use of antibiotics is associated with increasing bacterial resistance, and a great number of antibiotics are used incorrectly. In order to decrease the inappropriate use of antibiotics, several approaches have been proposed. Limiting the use of antimicrobials through formulary restrictions, often aimed at drugs with a specific resistance profile, shows benefits in improving antimicrobial susceptibilities and decreasing colonization by drug-resistant organisms. However, the restriction of one agent may result in the increased utilization of other agents. By using antibiotic cycling, the amount of antibiotics is maintained below the threshold where bacterial resistance develops, thus preserving highly efficient antibiotics. Unfortunately, cumulative evidence to date suggests that antibiotic cycling has limited efficacy in preventing antibiotic resistance. Finally, although there is still little clinical evidence available on antibiotic heterogeneity, the use of most of the existing antimicrobial classes could limit the emergence of resistance. This review summarizes information regarding antibiotic evaluation and available restrictive strategies to limit the use of antibiotics at hospitals with the aim of curtailing increasing antibiotic resistance.