The in vivo efficacy of
JNJ-Q2, a new broad-spectrum
fluoroquinolone (FQ), was evaluated in a murine
septicemia model with
methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) and in a Streptococcus pneumoniae lower
respiratory tract infection model.
JNJ-Q2 and comparators were also evaluated in an acute murine skin
infection model using a community-acquired MRSA strain and in an established skin
infection (ESI) model using a hospital-acquired strain, for which the selection of resistant mutants was also determined.
JNJ-Q2 demonstrated activity in the MSSA
septicemia model that was comparable to that
moxifloxacin (
JNJ-Q2 50% effective dose [ED(50)], 0.2 mg/kg of
body weight administered subcutaneously [s.c.] and 2 mg/kg administered orally [p.o.]) and activity in the MRSA
septicemia model that was superior to that of
vancomycin (
JNJ-Q2 ED(50), 1.6 mg/kg administered s.c.). In an S. pneumoniae lower
respiratory tract infection model,
JNJ-Q2 displayed activity (ED(50), 1.9 mg/kg administered s.c. and 7.4 mg/kg administered p.o.) that was comparable to that of
gemifloxacin and superior to that of
moxifloxacin. In both MRSA skin
infection models, treatment with
JNJ-Q2 resulted in dose-dependent reductions in bacterial titers in the skin, with the response to
JNJ-Q2 at each dose exceeding the responses of the comparators
ciprofloxacin,
moxifloxacin,
linezolid, and
vancomycin. Additionally, in the ESI model,
JNJ-Q2 showed a low or nondetectable propensity for
ciprofloxacin resistance selection, in contrast to the selection of
ciprofloxacin-resistant mutants observed for both
ciprofloxacin and
moxifloxacin.
JNJ-Q2 demonstrated activity that was comparable or superior to the activity of
fluoroquinolone or antistaphylococcal comparators in several local and systemic skin
infection models performed with both S. aureus and S. pneumoniae and is currently being evaluated in phase II human clinical trials.