New Antibiotics May Help Against MRSA

(December 23, 2009) - Researchers say they have discovered two antibiotics (Read about "Antibiotics") that may be more effective against methicillin-resistant Staphylococcus aureus (MRSA). The often feared and sometimes deadly infections caused by MRSA (Read about "Staph & MRSA") are emerging as an even more virulent strain in community settings and on athletic teams, and raising new concerns about antibiotic resistance.

Right now, the new community-associated strain of MRSA is responsive to more, but sometimes different antibiotics than its hospital relative, experts say. But those antibiotics will almost certainly lose their effectiveness as they are used more widely, and efforts are under way to combat that issue.

A new study by pharmacy researchers has identified two antibiotics that appear less likely to cause future antibiotic resistance, and others that if used would allow resistance to emerge more quickly. This analysis was just published in the International Journal of Antimicrobial Agents.

"The problem with invasive MRSA infections is very real and is now moving from the hospital setting to the community," said George Allen, one of the researchers. "The community-based strain in some ways is even more apt to cause serious problems than those most often acquired in hospitals, and increasing quite dramatically in prevalence.

"The good news is that so far the community strain is more treatable, if we can keep it that way," he said.

In the new research based on laboratory analysis, scientists identified linezolid and moxifloxacin as two antibiotics that would be effective against, and less apt to induce antibiotic resistance in the new strain of community-associated MRSA. That's of some interest because moxifloxacin, like other antibiotics in its class, has not been traditionally thought of as an appropriate agent for MRSA because resistance to it often develops rapidly.

Antibiotics that are most apt to cause rapid development of resistance against the community-associated strain of MRSA include clindamycin and doxycycline, the research found. The study was supported by the Society of Infectious Diseases Pharmacists.