Researchers in Germany have identified a new antimicrobial peptide that demonstrates significant activity against a variety of bacteria, including multiresistant human strains such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). The discovery was made while investigating the ancient metazoan organism Hydra magnipapillata.

The researchers from Christian-Albrechts-University and the University Medical Center Schleswig-Holstein Campus, Kiel, Germany report their findings in the December 2009 issue of the journal Antimicrobial Agents and Chemotherapy.

While occurrences of multidrug-resistant infections continue to increase, the discovery and development of drugs effective against these bacterial strains have slowed. Once commonly thought of as a hospital-acquired infection, MRSA has now spread to the community (now known as community acquired or CA-MRSA) and is infecting previously healthy young people who have not been recently hospitalized or undergone a medical procedure. Past research has proven that ancient organisms are well equipped at preventing infectious pathogens from entering the body and given the desperate need for new drug targets, further exploration of these organisms is warranted.

MRSA has already developed resistance to CA-MRSA human antimicrobial peptides and prior studies have shown antibacterial immune responses in the simple metazoan Hydra magnipapillata to include bactericidal peptides with novel structural features and modes of action. In the study researchers identified the antimicrobial peptide arminin 1a from Hydra and found that it exhibited significant and wide-spread activity against bacteria including MRSA and enterococci, a common cause of nosocomial infections that is also drug-resistant. Further observations revealed that bacteria are killed when the bacterial cell wall is disrupted and the antibacterial activity of arminin 1a isn't affected by exposure to salt in human blood. Finally, researchers determined that arminin 1a doesn't share any ancestry with any known antimicrobial peptides.

"Our data suggest that ancient metazoan organisms such as Hydra hold promise for the detection of novel antimicrobial molecules and the treatment of infections caused by the multiresistant bacteria," say the researchers.