July 21 2008

Dear Colleague:

This is the fourth issue of CGD's monthly e-newsletter devoted to news and information about the global problem of drug resistance, with special attention to resistance in the developing world. In this issue, we draw attention to a new regional initiative targeting resistance. The European Union has announced that November 18 will become annual "Antibiotic Awareness day". The European Center for Disease Prevention and Control and partners will use this annual event to bring attention to responsible antibiotic use conduct. A link to additional information about this initiative is in the "partner resources" section below.

In this month's feature column, we offer you some highlights from the Drug Resistance Working Group's new paper that characterizes the global drug resistance problem. The paper provides an overview of the magnitude of resistance and analyzes key drivers of resistance emergence and transmission with the aim of highlighting commonalities and differences in drivers across diseases. The paper is now available online at the Drug Resistance and Global Health Website.

Finally, for an update on global ART-resistance surveillance efforts, I encourage you to visit the recent supplement to Antiviral Therapy, which contains 14 relevant articles. The encouraging news is that ARV resistance is measured at “low” levels (under 5%) in many countries. But there is no room for complacency as treatment programs are still relatively new, and are scaling up at a rapid rate.

Thank you for subscribing to this e-newsletter. As always, we welcome your comments and suggestions on our program of work.

Regards,

Rachel Nugent

Deputy Director for Global Health

Center for Global Development

FEATURED COLUMN

Drivers of resistance emergence and transmission across diseases: the "characterization paper"

By Alex Beith, consultant to the CGD Drug Resistance Working Group

As part of its work program, the CGD Drug Resistance Working Group commissioned a paper to "characterize" the global drug resistance problem. The paper's message is that greater coordination across diseases would better inform global policy-making and result in more valuable joint, coordinated and effective action.

The paper first presents a brief overview of the magnitude of resistance, focusing on global health priority organisms such as Shigella and Vibrio cholerae (to represent enteric pathogens), Streptococcus pneumoniae (to represent respiratory pathogens), malaria, tuberculosis and HIV/AIDS. It then analyzes key drivers of drug resistance, using a dynamic, interactive tripartite classification composed of health system drivers, behavioral drivers and drug/drug technology drivers, seeking to draw out commonalities in drivers across diseases.

Not surprisingly, we have found important commonalities in resistance across diseases. What is surprising is that efforts to control drug resistance are fragmented -- generally by disease -- and so can't take advantage of those commonalities to get resistance under control. We highlight here several of the common ways that drug resistance affects different diseases.

The common problems that plague developing country health systems -- among them unavailable, ineffective, or costly services -- lead to behavior that favors resistance emergence, particularly in settings where drugs are easily available and affordable through informal channels. Both providers and patients are responsible. Weak infection control allows resistant organisms to be transmitted from person to person, especially for S. pneumoniae and Shigella, but also for tuberculosis. Treatment with inappropriate drugs or for the incorrect illness (such as antimalarials for a febrile illness that is not malaria) also drives resistance -- this commonly occurs through self-medication for malaria and through inappropriate prescribing of antibiotics for cholera (in non-epidemic settings).

Lack of treatment adherence among patients sets the stage for the emergence of resistant pathogens and is a particularly important driver when treatment is long-term -- such as for TB and HIV. The use of monotherapy provided conditions for ART resistance until the advent of HAART and for anti-TB drug resistance until the introduction of fixed-drug combinations (FDCs). Current malaria guidelines recommend that artemisinin, the only anti-malarial to which no resistance has yet been shown, be used in combination with other drugs to slow the emergence of resistance.

Rapid highly-accurate diagnostics need to be used more often and properly to mitigate some of the resistance drivers mentioned above. Currently, in too many health care settings, when presented with an uncertain pathogen or susceptibility profile, providers tend towards over (and possibly unnecessary) prescription. Even with rapid diagnostics in hand, a provider will sometimes ignore the results and give drugs to a patient with a negative test. What lies behind this troubling behavior? Across diseases, but particularly for antimicrobials and antimalarials, it is common for a provider to feel (real or perceived) pressure from the patient to treat; and it is often simply easier to prescribe a drug and "close the transaction." This situation not only compromises patient care, but also drives drug resistance in the longer term. Care providers need support from decision tools that can help them when informing the patient of his/her treatment (or not) decision.

The characterization paper also points to resistance surveillance and monitoring, strengthened supply chain management, and coordinated regulatory practices as areas to target the Working Group's attention for recommendations that might have considerable cross-disease relevance and benefit.

To access the paper, please click here.

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