Q&A: Antibiotic resistance: what more do we know and what more can we do?

Is the problem of antibiotic resistance getting worse? Yes. Resistance to antibiotics continues to be a significant and growing medical problem across the globe. In the US, the Centers for Disease Control recently released a report showing that infections due to carbapenemresistant Enterobacteriaceae (CRE), which are associated with mortality rates between 40% and 50%, rose from 1.2% to 4.2% over the decade from 2001 to 2011 [1]. In the clinically important Klebsiella subset of these pathogens, the rise over the same time period was from 1.6% to 10.4%. Carbapenems are among the last resort antibiotics we have to treat infections of Gramnegative bacteria and this steady erosion of their efficacy is especially concerning. The cause is the spread of genes that encode enzymes that destroy these antibiotics, in particular KPC (Klebsiella pneumoniae carbapenemase) and NDM (New Delhi metallo-betalactamase) [2]. The latter has been found widespread in the environment, including the water supply on the Indian subcontinent [3]. Infections due to multidrug resistant Neisseria gonorrhea are also on the rise. Once easily treated with available antibiotics, the emergence of drug-resistant strains resulting in clinical failures is becoming more common. A recent study in a Toronto clinic showed that 6.77% of cases could not be cured with standard oral antibiotic therapy [4]. Outbreaks of infections caused by multidrug and sometimes pan-resistant epidemic clones of Acinetobacter baumannii are increasingly reported in health care settings across the globe. The establishment of methicillin-resistant Staphylococcus aureus (MRSA) in the community at large as well as in hospitals is continuing; over 460,000 MRSA infections required hospitalization in the US in 2009 [5]. There are now circulating