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Simple Changes to Antibiotic Treatment May Help Beat MRSA, Researchers Find

Penicillin may have new role

Microbiologists have identified how methicillin-resistant Staphylococcus aureus (MRSA) may be more effectively treated by modern-day antibiotics if old-fashioned penicillin is also used. A team at the University of Liverpool in the United Kingdom and at the National University of Ireland Galway have shown that, although penicillin does not kill the bacteria, it does weaken their virulence, making it easier for the immune system and other antibiotics to eradicate the infection. The research was published in the Journal of Infectious Diseases.

“Although aggressive hospital infection-control initiatives appear to be having a positive impact on hospital-acquired MRSA rates in some developed countries, the global burden still remains unacceptably high,” said study co-leader Professor Aras Kadioglu of Liverpool University. “Infections caused by community-associated MRSA strains and by strains that are currently methicillin sensitive are increasing at a worrying speed. Given the escalating antimicrobial resistance crisis, it is imperative to identify new therapeutic strategies and to re-evaluate how current antimicrobial drugs are used.”

Professor James O’Gara of the National University of Ireland Galway commented: “Our findings explain the anti-virulence mechanism of penicillin-type antibiotics and support the re-introduction of these drugs as an adjunct therapeutic for MRSA infections. MRSA can be extremely virulent, which is part of the challenge in treating it. Our laboratory research shows that when exposed to penicillin, the bacteria switches off its toxin genes and instead concentrates on thickening its cell wall to resist the antibiotic. Our immune systems can then take advantage of this compromised state to destroy the bacteria.”

This new treatment strategy for MRSA infections has the potential to change the current clinical guidelines for the treatment of patients with MRSA infections in both hospital and community settings, the authors said. A recent randomized controlled trial in Australia involving 60 patients showed that the beta-lactam antibiotic flucloxacillin in combination with vancomycin significantly reduced the duration of MRSA sepsis from 3.0 days to 1.9 days.

“The clinical findings in Australia are very important, and now we have the key laboratory data that help explain why the combination of two antibiotics is better than one. The beauty of this approach is that penicillin-type antibiotics are not only widely available and safe, but can potentially and more easily be included in clinical practice without the need for long and expensive clinical trials needed for new drugs,” O’Gara said.

Source: University of Liverpool; November 15, 2016.

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