title: Whole animal automated platform for drug discovery against multi-drug resistant Staphylococcus aureus.
abstract: Staphylococcus aureus, the leading cause of hospital-acquired infections in the United States, is also pathogenic to the model nematode Caenorhabditis elegans. The C. elegans-S. aureus infection model was previously carried out on solid agar plates where the bacteriovorous C. elegans feeds on a lawn of S. aureus. However, agar-based assays are not amenable to large scale screens for antibacterial compounds. We have developed a high throughput liquid screening assay that uses robotic instrumentation to dispense a precise amount of methicillin resistant S. aureus (MRSA) and worms in 384-well assay plates, followed by automated microscopy and image analysis. In validation of the liquid assay, an MRSA cell wall defective mutant, MW2ΔtarO, which is attenuated for killing in the agar-based assay, was found to be less virulent in the liquid assay. This robust assay with a Z'-factor consistently greater than 0.5 was utilized to screen the Biomol 4 compound library consisting of 640 small molecules with well characterized bioactivities. As proof of principle, 27 of the 30 clinically used antibiotics present in the library conferred increased C. elegans survival and were identified as hits in the screen. Surprisingly, the antihelminthic drug closantel was also identified as a hit in the screen. In further studies, we confirmed the anti-staphylococcal activity of closantel against vancomycin-resistant S. aureus isolates and other Gram-positive bacteria. The liquid C. elegans-S. aureus assay described here allows screening for anti-staphylococcal compounds that are not toxic to the host.
authors.affiliation: Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America ; Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Rajmohan
authors.initials: R
authors.lastname: Rajamuthiah
authors.affiliation: Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America ; Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Beth Burgwyn
authors.initials: BB
authors.lastname: Fuchs
authors.affiliation: Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America ; Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Elamparithi
authors.initials: E
authors.lastname: Jayamani
authors.affiliation: Department of Animal Science, Chonbuk National University, Jeonju, Republic of Korea.
authors.forename: Younghoon
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Jonah
authors.initials: J
authors.lastname: Larkins-Ford
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Annie
authors.initials: A
authors.lastname: Conery
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
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, United States of America ; Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Mylonakis
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000382:microbiology*; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D057166:High-Throughput Screening Assays / Q000379:methods; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics*; D012458:Salicylanilides; D054852:Small Molecule Libraries / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D012458:Salicylanilides; D054852:Small Molecule Libraries; C023342:closantel