Journal of Antimicrobial Chemotherapy (1999) 44, 229-234
© 1999 The British Society for Antimicrobial Chemotherapy
The antibacterial efficacy of trovafloxacin against an experimental infection with Listeria monocytogenes in hydrocortisone-treated mice
Department of Medical Microbiology, Leiden University Medical Centre, PO Box 9600, 2300 RC Leiden, The Netherlands
The efficacy of trovafloxacin in treating Listeria monocytogenes infections in glucocorticosteroid-treated mice was compared with the efficacy of amoxycillin. Swiss mice were treated with daily injections of 2.5 mg hydrocortisone sc and then infected iv with 1 x 10 7cfu of L. monocytogenes. Untreated, this level of infection resulted in 100% mortality between day 3 and day 5 after infection.Both sc trovafloxacin and amoxycillin were effective in reducing the number of viable L. monocytogenes in the liver and spleen. Although the MIC of amoxycillin for this isolate of L. monocytogeneswas lower than that of trovafloxacin (0.063 mg/L versus 0.5 mg/L, respectively), trovafloxacin was more efficacious in vivo after a single dose in the dose range between 12.5 and 100 mg/kg than was amoxycillin. After treatment with trovafloxacin at 100 mg/kg bodyweight od for 3 days, a mean log10cfu of 1.58 and 2.52 L. monocytogenescould be recovered from the spleens and livers, respectively, whereas after treatment with amoxycillin at 100 mg/kg bodyweight every 8 h for 3 days, the mean log10cfu values were 2.36 and 2.02, respectively. These differences were statistically not significant. Results of the present study show that the antibacterial efficacy of trovafloxacin against L. monocytogenes in our animal model is equivalent to that of amoxycillin.