The Drug Resistance Index (DRI) is an important tool to understand the development of drug resistance. About the latest trends we asked Dr. Eili Klein, fellow at the Center for Disease Dynamics, Economics & Policy, who is involved in the design and development of the Index.
Mr. Klein, according to the Drug Resistance Index, the effectiveness of antibiotics has declined in 24 of 27 countries. This sounds alarming. Can it be assumed, that this relation (24:27) is reflecting the worldwide situation?
The DRI combines use and resistance to estimate a relative effectiveness of antibiotics in a country. In the last several years there have been increases in resistance globally and few new antibiotics, thus the reason the relative effectiveness of antibiotics has declined in most countries in our sample. The majority of the countries included were European countries, which are more likely to have better infection control and antimicrobial stewardship interventions than many developing countries (largely missing in our sample). In the few developing countries for which we had data the DRI did increase, and we expect, since resistance can easily spread across borders, that globally the effectiveness of antibiotics has declined. Without concerted efforts to both conserve existing drugs and develop new ones, we expect this trend to continue.
The 27 countries were selected randomly?
The 27 countries in our sample were not randomly selected, but were the countries that report data needed to calculate the index. In the instance that you were examining, we included six of the most common pathogens (E. coli, K. pneumoniae, S. aureus, P. aeruginosa, E. faecium, and E. faecalis). Data on resistance for these pathogens to commonly used antibiotics was only available for these 27 countries, and even within this restricted group we only had data on four of the pathogens for a few of the countries. In this case we were comparing across countries, however, the relative burden of each pathogen was not taken into consideration, and some pathogens that may be problematic in developing countries but not in developed countries were excluded. While the DRI provides a good comparison across countries, the same caution should be used in its interpretation as in interpreting a stock index (which is what it was modeled after).
Only in Germany and Sweden things have got markedly better. In which way do they deal “better” with the problem than the other covered countries?
The DRIs for both Sweden and Germany declined largely due to a decrease in resistance rates for E. coli, P. aeruginosa, E. faecalis and E. faecium to broad-spectrum penicillins (piperacillin-tazobactam for P. aeruginosa and aminopenicillins for the remaining three). We don’t have a answer for why resistance fell to those pathogens, though both have been at the forefront of combating overuse of antibiotics and improving infection prevention.
Does CDDEP plan to develop the Drug Resistance Index in any direction?
The goal of the DRI is to communicate relative changes in antibiotic effectiveness at multiple levels. Globally, we intend to expand the number of countries included in the data and to publish regular updates regarding cross-country comparisons and time trends. The DRI can also be an effective tool at the hospital level. We have been testing implementations of the DRI in hospitals in India, Nepal and South Africa to track trends in their overall resistance patterns and analyze the effect of their infection control and antimicrobial stewardship interventions. As we move forward with the DRI, we hope to increase its use in hospitals as a means of conveying information in a simple effective manner as well as at regional scales to help hospitals coordinate on the problems of drug resistance.