Wrong antibiotic 'can make superbug worse'

Using a common family of antibiotics to treat the MRSA superbug is likely to fire up an immune response that triggers harmful inflammation, scientists say.

Treatment with the wrong antibiotic could make MRSA superbug infections far worse, a study suggests.

Using a common family of drugs called beta-lactam antibiotics is likely to fire up an immune response that triggers harmful inflammation, scientists have discovered.

Beta-lactam antibiotics consist of a broad range of medicines including penicillin derivatives. They mostly work by damaging bacterial cell walls.

Tests in mice showed that when MRSA (methicillin resistant Staphylococcus aureus) bugs are exposed to the antibiotics, a gene in the microbe is activated that results in fragments of cell wall being released.

The fragments are recognised by the immune system, activating a harmful inflammatory response. In MRSA-infected mice, this led to worse skin infections.

Lead scientist Dr George Liu, from Cedars-Sinai Medical Center in Los Angeles, said: "Individuals infected with MRSA who receive a beta-lactam antibiotic - one of the most common types of antibiotics - could end up being sicker than if they received no treatment at all.

"Our findings underscore the urgent need to improve awareness of MRSA and rapidly diagnose these infections to avoid prescribing antibiotics that could put patients' lives at risk."

Colleague Dr Sabrina Muller added: "A poor choice of antibiotic can make MRSA infection worse compared to no treatment."

The findings could have important clinical implications, say the scientists writing in the journal Cell Host & Microbe. But they stress that more research is needed involving human patients.