Abstract: A compound as represented by the general formula (I) shown below exhibits high antibacterial activity against gram-positive bacteria, in particular, such drug-resistant bacteria as mRNA, PRSP and VRE: wherein R1 is a methyl group, a fluoromethyl group, a methoxymethyl group, an acetoxymethyl group, a hydroxymethyl group or a methylene; R2 is a hydrogen atom, a lower alkyl group having 1 to 3 carbon atoms, or a pharmaceutically acceptable cation and an ester of a prodrug; R3 is a hydrogen atom or a halogen atom; R4 is a hydrogen atom, a lower alkyl group having 1 to 3 carbon atoms, a fluoromethyl group, a trifluoromethyl group or a fluorine atom; and R5 is a hydrogen atom or a fluorine atom, with exceptions where R1 is a methyl group, R4 and R5 are at the same time a hydrogen atom, and R3 is a fluorine atom.

Abstract: OBJECT To provide novel quinolonecarboxylic acid compounds serving as safe, strong antibacterial agents that are effective against drug-resistant bacteria that are less susceptible to conventional antibacterial agents. SOLVING MEANS There are provided 7-(4-substituted-3-cyclopropylaminomethylpyrrolidinyl)quinolonecarboxylic acid derivatives (such as 1-cyclopropyl-7-[(3S,4S)-3-cyclopropylaminomethyl-4-fluoro-1-pyrrolidinyl]-6-fluoro-1,4-dihydro-8-methoxy-4-oxo-3-quinolinecarboxylic acid) that exhibit strong antibacterial activity against gram-positive bacteria, such as MRSA, PRSP and VRE, while being safe.

Abstract: A compound as represented by the general formula (I) shown below exhibits high antibacterial activity against gram-positive bacteria, in particular, such drug-resistant bacteria as mRNA, PRSP and VRE: wherein R1 is a methyl group, a fluoromethyl group, a methoxymethyl group, an acetoxymethyl group, a hydroxymethyl group or a methylene; R2 is a hydrogen atom, a lower alkyl group having 1 to 3 carbon atoms, or a pharmaceutically acceptable cation and an ester of a prodrug; R3 is a hydrogen atom or a halogen atom; R4 is a hydrogen atom, a lower alkyl group having 1 to 3 carbon atoms, a fluoromethyl group, a trifluoromethyl group or a fluorine atom; and R5 is a hydrogen atom or a fluorine atom, with exceptions where R1 is a methyl group, R4 and R5 are at the same time a hydrogen atom, and R3 is a fluorine atom.