Sd. Putnam et al., IN-VITRO ANTIMICROBIAL ACTIVITY AND MIC QUALITY-CONTROL GUIDELINES OFRPR-106972 (RPR-112808 RPR106950) - A NOVEL ORALLY-ADMINISTERED STREPTOGRAMIN COMBINATION, Diagnostic microbiology and infectious disease, 28(3), 1997, pp. 139-147
RPR 106972 is a novel oral streptogramin combination with reported the
rapeutic potency against Gram-positive and certain respiratory tract p
athogens. MICs for RPR 106972, quinupristin/dalfopristin, and seven co
mparison drugs were determined by the reference methods against 337 st
rains selected to define spectrum and potency. RPR 106972 demonstrated
antimicrobial activity against oxacillin-susceptible and -resistant S
taphylococcus aureus (MIG ranges of 0.12 to 2 mu g/ml and 0.5 to 2 mu
g/ml, respectively), and coagulase-negative staphylococci were also in
hibited by RPR 106972 (MIC90, less than or equal to 0.5 mu g/ml) and q
uinupristin/dalfopristin (MIC90, less than or equal to 0.25 mu g/ml).
Against all streptococcal strains ts tested (including penicillin-resi
stant pneumococcus), RPR 106972 was highly active with MIC results at
less than or equal to 1 mu g/ml. RPR 106972 inhibited Corynebacterium
jeikeium (MIC90, 0.5 mu g/ml), Moraxella catarrhalis (MIC90, 0.25 mu g
/ml), and some Haemophilus influenzae (MIC50, 2 mu g/ml). RPR 106972 a
nd quinupristin/dalfopristin demonstrated little activity against Ente
rococcus faecalis (MIC(90)s, 4 to 32 mu g/ml) as compared to Enterococ
cus faecium (MIC(90)s, 0.5 to I mu g/ml) and other Enterococcus ssp. (
MIC(90)s, 1 mu g/ml). Studies to establish MIC quality-control guideli
nes indicated the following ranges: for E. faecalis ATCC 29212, 0.5 to
4 mu g/ml; for S. aureus ATCC 29213, 0.25 to 2 mu g/ml; and for Strep
tococcus pneumoniae ATCC 49619, 0.06 to 0.5 mu g/ml. The results of th
is study indicate that the in vitro activity of RPR 106972 against Gra
m-positive bacteria and selected Gram-negative respiratory organisms i
s promising and warrants additional studies of pharmacokinetics, and i
n vivo infection model dynamics. (C) 1997 Elsevier Science Inc.