title: Insect-derived cecropins display activity against Acinetobacter baumannii in a whole-animal high-throughput Caenorhabditis elegans model.
abstract: The rise of multidrug-resistant Acinetobacter baumannii and a concomitant decrease in antibiotic treatment options warrants a search for new classes of antibacterial agents. We have found that A. baumannii is pathogenic and lethal to the model host organism Caenorhabditis elegans and have exploited this phenomenon to develop an automated, high-throughput, high-content screening assay in liquid culture that can be used to identify novel antibiotics effective against A. baumannii. The screening assay involves coincubating C. elegans with A. baumannii in 384-well plates containing potential antibacterial compounds. At the end of the incubation period, worms are stained with a dye that stains only dead animals, and images are acquired using automated microscopy and then analyzed using an automated image analysis program. This robust assay yields a Z' factor consistently greater than 0.7. In a pilot experiment to test the efficacy of the assay, we screened a small custom library of synthetic antimicrobial peptides (AMPs) that were synthesized using publicly available sequence data and/or transcriptomic data from immune-challenged insects. We identified cecropin A and 14 other cecropin or cecropin-like peptides that were able to enhance C. elegans survival in the presence of A. baumannii. Interestingly, one particular hit, BR003-cecropin A, a cationic peptide synthesized by the mosquito Aedes aegypti, showed antibiotic activity against a panel of Gram-negative bacteria and exhibited a low MIC (5 μg/ml) against A. baumannii. BR003-cecropin A causes membrane permeability in A. baumannii, which could be the underlying mechanism of its lethality.
authors.affiliation: Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, USA Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Elamparithi
authors.initials: E
authors.lastname: Jayamani
authors.affiliation: Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, USA Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Rajmohan
authors.initials: R
authors.lastname: Rajamuthiah
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Jonah
authors.initials: J
authors.lastname: Larkins-Ford
authors.affiliation: Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, USA Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Beth Burgwyn
authors.initials: BB
authors.lastname: Fuchs
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Annie L
authors.initials: AL
authors.lastname: Conery
authors.affiliation: Institute of Phytopathology and Applied Zoology, Justus-Liebig University, Giessen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Vilcinskas
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Frederick M
authors.initials: FM
authors.lastname: Ausubel
authors.affiliation: Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, USA Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA emylonakis@lifespan.org.
authors.forename: Eleftherios
authors.identifier: http://orcid.org/0000-0002-4624-0777
authors.initials: E
authors.lastname: Mylonakis
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017173:Caenorhabditis elegans / Q000382:microbiology*; D054807:Cecropins / Q000494:pharmacology*; D004195:Disease Models, Animal; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D007313:Insecta / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D054807:Cecropins