Inhibitory Effect of the Marine Sponge Amphimidon chloros Extracts Against Multidrug-Resistant Bacteria

Antibiotic misuse has led to the development and spread of multidrug-resistant (MDR) microorganisms. This study evaluated the antibacterial activity of n-hexane, ethyl acetate, and aqueous extracts of the marine sponge Amphimidon chloros. The antibacterial activity of nhexane, ethyl acetate, and aqueous extracts was evaluated using broth microdilution and disc diffusion. The chemical composition of the extracts was analysed using Liquid ChromatographyMass spectrometry (LC-MS). The antibacterial potency of the extracts was in the following order: aqueous > n-hexane > ethyl acetate extracts. The most significant inhibitory activity of theaqueous extract was against Shigella flexneri, with an inhibition zone of 20.6 mm. Klebsiella pneumonia, Pseudomonas aeruginosa, and Listeria monocytogenes were utterly resistant to ampicillin and chloramphenicol; however, the aqueous extract efficiently inhibited these bacteria. The extract MIC ranged from 0.0195–2.5 mg/mL. With maximal inhibition against Staphylococcus aureus (0.0195 mg/mL), Bacillus cereus (0.0390 mg/mL), Shigella flexneri (0.0390 mg/mL), and Salmonella enterica (0.0781 mg/mL). While L. monocytogenes (0.3125 mg/mL) and S. aureus (0.625 mg/mL) were the only Gram-positive bacteria inhibited, the ethyl acetate extract was equally effective (MIC of 0.3125 mg/mL) against Gram-negative bacteria, including K. pneumonia, S. typhi, S. enterica, Enterobacter aerogenes, and E. coli. The n-hexane extract inhibited S. aureus, S. flexneri, and S. enterica with a MIC value of 0.1562/mL. The most prevalent phytochemicals in the aqueous and n-hexane extracts from the LC-MS study were nakinadine and kermaphidine. The study revealed that the aqueous extract of A. chloros possesses both Gram-positive and Gram-negative antibacterial activity.