Background:

BAY-Y 3118 is a new chlorofluoroquinolone with antimicrobial activity.

BAY-Y 3118 is potent against Haemophilhs influenzae, Moraxela catarrhalis, Acinetobacter baumannii, Xanthomonas maltophiia, gram-positive cocci, and anaerobes; MICs for 50%o of the strains (MIC50s) and MIC90s are ≤0.015 and ≤0.015, ≤0.015 and ≤0.015, 0.03 and 2, 0.25 and 0.5, 0.06 and 1, and 0.12 and 0.25 μg/mL, respectively[1]. The cellular concentration-to-extracellular concentration ratio of BAY-Y 3118 is higher than 6.3 at extracellular concentrations ranging from 2 to 100 mg/L. The uptake of BAY-Y 3118 is rapid, reversible and nonsaturable. The intracellular penetration of BAY-Y 3118 is significantly affected by environmental temperature and cell viability. BAY-Y 3118 reaches high intracellular concentrations within human polymorphonuclear leukocytes (PMNs) and remains active intracellularly[2]. All strains of L. monocytogenes and other Listeria spp. are highly susceptible; the MICs for these organisms ranges from 0.062 to 0.25 μg/mL. BAY-Y 3118 is rapidly bactericidal in vitro, with a postantibiotic effect occurring for 3 h after removal of the antibiotic. L. monocytogenes is eliminated from infected L929 cells treated with BAY-Y 3118, suggesting a bactericidal effect on the listeriae in these cells[3].

Immunocompetent mice are rapidly cured by treatment with 4 mg every 12 h. Concomitantly, the levels of interleukin 6 and gamma interferon in mouse sera decline rapidly. In immunocompetent mice, treatment with 2 mg of BAY-Y 3118 every 12 h results in a greater initial reduction in the listerial counts in the organs than treatment with 2 mg of ampicillin every 12 h. BAY-Y 3118 completely eliminates L. monocytogenes from the livers and spleens of chronically infected nude mice[3].

[1]. Fass RJ, et al. In vitro activity of Bay y 3118, a new quinolone. Antimicrob Agents Chemother. 1993 Nov;37(11):2348-57. [2]. García I, et al. Intracellular penetration and activity of BAY Y 3118 in human polymorphonuclear leukocytes. Antimicrob Agents Chemother. 1994 Oct;38(10):2426-9. [3]. Nichterlein T, et al. Bay Y 3118, a new quinolone derivative, rapidly eradicates Listeria monocytogenes from infected mice and L929 cells. Antimicrob Agents Chemother. 1994 Jul;38(7):1501-6.