SUSCEPTIBILITIES OF 228 PENICILLIN-SUSCEPTIBLE AND ERYTHROMYCIN-SUSCEPTIBLE AND PENICILLIN-RESISTANT AND ERYTHROMYCIN-RESISTANT PNEUMOCOCCITO RU-64004, A NEW KETOLIDE, COMPARED WITH SUSCEPTIBILITIES TO 16 OTHER AGENTS
Lm. Ednie et al., SUSCEPTIBILITIES OF 228 PENICILLIN-SUSCEPTIBLE AND ERYTHROMYCIN-SUSCEPTIBLE AND PENICILLIN-RESISTANT AND ERYTHROMYCIN-RESISTANT PNEUMOCOCCITO RU-64004, A NEW KETOLIDE, COMPARED WITH SUSCEPTIBILITIES TO 16 OTHER AGENTS, Antimicrobial agents and chemotherapy, 41(5), 1997, pp. 1033-1036
The susceptibilities of 228 penicillin- and erythromycin-susceptible a
nd -resistant pneumococci to RU 64004, a new ketolide, were tested by
agar dilution, and the results were compared with those for penicillin
G, erythromycin, azithromycin, clarithromycin, rokitamycin, clindamyc
in, pristinamycin, ciprofloxacin, sparfloxacin, trimethoprim-sulfameth
oxazole, doxycycline, chloramphenicol, cefuroxime, ceftriaxone, imipen
em, and vancomycin, RU 64004 was very active against all strains teste
d, with MICs at which 90% of the isolates are inhibited (MIC(90)s) of
0.016 mu g/ml for erythromycin-susceptible strains (MIG, less than or
equal to 0.25 mu g/ml) and 0.25 mu g/ml for erythromycin-resistant str
ains (MIC, greater than or equal to 0,5 mu g/ml). All other macrolides
had MIC(90)s of 0.03 to 0.25 and greater than or equal to 128 mu g/ml
for erythromycin-susceptible and -resistant strains, respectively. Am
ong erythromycin-resistant strains, clindamycin MICs for 28 of 91 (30.
7%) were less than or equal to 0,125 mu g/ml. Pristinamycin MICs for a
ll strains were less than or equal to 1,0 mu g/ml. MIC(90)s of ciprofl
oxacin and sparfloxacin were 4.0 and 0.25 mu g/ml, respectively, and w
ere unaffected by susceptibility to penicillin or erythromycin, Vancom
ycin and imipenem inhibited all strains at less than or equal to 0.5 a
nd 0.25 mu g/ml, respectively, MICs of cefuroxime and cefotaxime rose
with those of penicillin G, MICs of trimethoprim-sulfamethoxazole, dox
ycycline, and chloramphenicol were variable but were generally higher
for penicillin- and erythromycin-resistant strains. RU 64004 is the fi
rst member of the macrolide group which has low MICs for erythromycin-
resistant pneumococci.