Levulinic acid or its derivatives have strong antibiotic activities against drug-resistant bacteria and other bacteria. Particularly, levulinic acid or their derivatives have excellent antibiotic activities against common-antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (hereinafter referred to as MRSA), drug-resistant Pseudomonas aeruginosa and vancomycin-resistant Enterococcus (VRE). Levulinic acid or its derivatives have excellent antibiotic activities against bacteria such as Staphylococcus aureus and Enterococcus faecium. Additionally, levulinic acid or its derivatives have antibiotic activities against yeast.

Levulinic acid or its derivatives have effective antibiotic activities against bacteria infecting the finny tribe, for example, Lactococcus garvieae, Edwardsiella tarda and Vibrio anguillarum. Levulinic acid or their derivatives have excellent antibiotic activities against tooth-decaying bacteria such as Streptococcus mutans, Streptococcus sobrinus-coykendal, Streptococcus doweni and Streptococcus salivarius. Levulinic acid or their derivatives have excellent antibiotic activities against Salmonella typhimurium, the pathogen in poultry and Propionibacterium acnes KCTC 3326, pimple-causing bacteria. As stated above, levulinic acid or its derivatives have antibiotic activities against various microorganisms. 

Levulinic acid or their derivatives are used as antibiotics against common-antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus, drug-resistant Pseudomonas aeruginosa and vancomycin-resistant Enterococcus, or used as therapeutics and prevention against diseases caused by bacteria involved tooth decay, generation of pimples and pathogenesis for animals including domestic animal, poultry and finny tribe.