Sunday, 27 April 2014

Antimicrobial resistance

The ability of bacteria to evolve in response to pressure from antibiotics has been recognized since the discovery of penicillin. In less than a century, a complex array of factors has led to the emergence of bacteria that no longer respond to any approved antibiotics. Numerous recent calls to action have highlighted the urgent need to respond to this growing global health threat with improved surveillance and infection control, more judicious use of antibiotics, new prevention measures, and new therapeutic strategies to combat resistant bacteria.

Bacteria can acquire resistance through mutation or through horizontal transfer of genetic information. Resistant members of a population that are exposed to the selective pressure of antibacterial drugs will be amplified, which can ultimately result in treatment failures in the clinic. Resistance genes are ancient (even pre-dating human beings) and ubiquitous, and some of the most worrisome resistance genes have been found in diverse environmental samples, including drinking water. Furthermore, many bacterial species harboring resistance genes can colonize the human gut, skin, and other niches, where they serve as a ready source of infection when host defenses are breached. These bacteria can also serve as a source of AR genes for transfer to other bacteria, facilitating the interspecies spread of resistance.

AR is a complex and multifaceted problem that is driven by many factors, including:
  • Bacterial population density in health care facilities, which allows transfer of bacteria within a community and enables resistance to emerge;
  • Inadequate adherence to proven hospital hygiene measures;
  • An increasing number of high risk populations, including chemotherapy, dialysis, and transplant patients as well as those in long-term care facilities;
  • Overuse of antibiotics in agriculture;
  • Global travel and trade, which can lead to transfer of resistant infections and resistance genes;
  • Poor sanitation in certain areas, which can contaminate water systems and spread resistant bacteria in sewage;
  • Inappropriate use of antibiotics in human medicine (e.g., for viral infections);
  • Overprescribing of broad-spectrum drugs, which can exert selective pressure on commensal bacteria and predispose to secondary infection; and
  • Lack of rapid diagnostics to help guide appropriate use of antibiotics.
Antimicrobial resistance has become a global crisis. In the U.S. alone, drug-resistant infections cause roughly 23,000 deaths a year, and the supply of new antibiotics has dwindled. In a commentary in JAMA this week, NIAID Director Anthony S. Fauci, M.D., along with colleague Hilary D. Marston, M.D., M.P.H., examine the problem and highlight how NIAID has recently adjusted its antimicrobial research efforts to apply innovative approaches to basic, clinical and translational research to address the problem.

To read the JAMA commentary, see JAMA

Posted by Tim Sandle