Mk. Lacy et al., Protective effect of trovafloxacin, ciprofloxacin and ampicillin against Streptococcus pneumoniae in a murine sepsis model, J ANTIMICRO, 44(4), 1999, pp. 477-481
Trovafloxacin is a new fluoroquinolone that has potent microbiological acti
vity against the pneumococcus, including penicillin-resistant strains. To e
valuate the protective effect of trovafloxacin, ciprofloxacin and ampicilli
n against penicillin-susceptible, -intermediate and -resistant strains of S
treptococcus pneumoniae, an intraperitoneal, immunocompetent mouse model of
sepsis was used. The minimum lethal dose (MLD) for each isolate was determ
ined in duplicate. A single sc dose of each antibiotic was administered ove
r a wide range of doses 1 h after the ip inoculation of the test isolate at
the MLD. The assessment of the protective dose for 50% of the population (
PD50) for each antimicrobial/bacteria combination was performed in triplica
te and the PD50 value was calculated at the end of 5 days. Results showed t
hat trovafloxacin provided PD50 values that were significantly lower than t
hose of ciprofloxacin for all isolates. For the penicillin-susceptible and
-intermediate isolates, the PD50 values of ampicillin were significantly lo
wer than those for either of the fluoroquinolones studied; however, trovafl
oxacin was statistically superior to both ciprofloxacin and ampicillin agai
nst the penicillin-resistant strain. Therefore, regardless of penicillin su
sceptibility, trovafloxacin has potent activity against Streptococcus pneum
oniae and may be a viable alternative for the treatment of penicillin-resis
tant isolates.