Bactericidal effect of bacteria isolated from the marine sponges Hymeniacidon perlevis and Halichondria panicea against carbapenem-resistant Acinetobacter baumannii

Aims: In this study, we evaluate the antimicrobial activity of bacteria isolated from marine sponges Hymeniacidon perlevis and Halichondria panicea against clinically relevant carbapenem-resistant Acinetobacter baumannii (CRAb) isolates. Methods and results We observe the inhibitory activity of 18 (out of 114) sponge-isolated bacterial strains using medium throughput solid agar overlay assays. These strains belong to the genera Lactococcus, Pseudomonas and Vagococcus. In addition, this antimicrobial activity is validated through a liquid co-cultivation challenge using an inhibitory strain of each genus. Conclusions We show the inhibitory effect of the sponge-isolated strains against clinically relevant, modern CRAb strains and characterize this antimicrobial activity as bactericidal. Significance and impact of the study A. baumannii is one of the most problematic nosocomial ESKAPE pathogens that imposes a global threat to human health, because of its increasing resistance to last-resort antibiotics. The World Health Organization has emphasized that new alternative treatments against CRAb strains are urgently needed. Our results show promising opportunities for the isolation of potentially new bactericidal compounds from sponge-isolated bacteria of the genera Lactococcus, Pseudomonas and Vagococcus to fight modern CRAb isolates and other problematic bacterial pathogens.