Characterization of Five Novel Anti-MRSA Compounds Identified Using a Whole-Animal Caenorhabditis elegans/ Galleria mellonella Sequential-Screening Approach

Rajamohammed Khader; Nagendran Tharmalingam; Biswajit Mishra; LewisOscar Felix; Frederick M Ausubel; Michael J Kelso; Eleftherios Mylonakis

doi:10.3390/antibiotics9080449

Characterization of Five Novel Anti-MRSA Compounds Identified Using a Whole-Animal Caenorhabditis elegans/ Galleria mellonella Sequential-Screening Approach

Antibiotics (Basel). 2020 Jul 27;9(8):449. doi: 10.3390/antibiotics9080449.

Authors

Rajamohammed Khader¹, Nagendran Tharmalingam¹, Biswajit Mishra¹, LewisOscar Felix¹, Frederick M Ausubel^{2

3}, Michael J Kelso^{4

5}, Eleftherios Mylonakis¹

Affiliations

¹ Infectious Diseases Division, Department of Medicine, Warren Alpert Medical School of Brown University, Rhode Island Hospital, Providence, RI 02903, USA.
² Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA.
³ Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
⁴ Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong 2522, Australia.
⁵ Illawarra Health and Medical Research Institute, University of Wollongong, Northfields Avenue, Wollongong 2522, Australia.

Abstract

There is a significant need to combat the growing challenge of antibacterial drug resistance. We have previously developed a whole-animal dual-screening platform that first used the nematode Caenorhabditis elegans, to identify low-toxicity antibacterial hits in a high-throughput format. The hits were then evaluated in the wax moth caterpillar Galleria mellonella infection model to confirm efficacy and low toxicity at a whole animal level. This multi-host approach is a powerful tool for revealing compounds that show antibacterial effects and relatively low toxicity at the whole organism level. This paper reports the use of the multi-host approach to identify and validate five new anti-staphylococcal compounds: (1) 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol(PPT), (2) (1S,2S)-2-[2-[[3-(1H-benzimidazol-2-yl)propyl]methylamino]ethyl]-6-fluoro-1,2,3,4-tetrahydro-1-(1-methylethyl)-2-naphthalenyl cyclopropanecarboxylate dihydrochloride(NNC), (3) 4,5,6,7-tetrabromobenzotriazole (TBB), (4) 3-[2-[2-chloro-4-[3-(2,6-dichlorophenyl)-5-(1-methylethyl)-4-isoxazolyl]methoxy]phenyl]ethenyl] benzoic acid(GW4064), and (5) N-(cyclopropylmethoxy)-3,4,5-trifluoro-2-[(4-iodo-2-methylphenyl)amino] benzamide(PD198306). The compounds reduced the severity of methicillin-resistant Staphylococcus aureus (MRSA, strain MW2) infections in both C. elegans and G. mellonella and showed minimal inhibitory concentrations (MICs) in the range of 2-8 µg/mL. Compounds NNC, PPT, and TBB permeabilized MRSA-MW2 cells to SYTOX green, suggesting that they target bacterial membranes. Compound TBB showed synergistic activity with doxycycline and oxacillin against MRSA-MW2, and compounds PPT, NNC, GW4064, and PD198306 synergized with doxycycline, polymyxin-B, gentamicin, and erythromycin, respectively. The study demonstrates the utility of the multi-host approach with follow-up hit characterization for prioritizing anti-MRSA compounds for further evaluation.

Keywords: Caenorhabditis elegans; Galleria mellonella; MIC; antibiotic; high-throughput screening (HTS), MRSA.

Grants and funding

P01 AI083214/NH/NIH HHS/United States