Pankuch G A, Jacobs M R, Appelbaum P C
Department of Pathology (Clinical Microbiology), Hershey Medical Center, Pennsylvania 17033, USA.
Antimicrob Agents Chemother. 1996 Sep;40(9):2071-4. doi: 10.1128/AAC.40.9.2071.
Broth MICs and time-kill studies were used to test the activity of RP 59500 (quinupristin-dalfopristin), RPR 106972, pyostacine (RP 7293), erythromycin, clarithromycin, and cefotaxime for four penicillin-susceptible (MICs of 0.008 to 0.03 microgram/ml), two penicillin-intermediate (MIC of 0.25 microgram/ml), and four penicillin-resistant (MIC of 2.0 to 4.0 micrograms/ml) strains of pneumococci: 6 of 10 strains were resistant to macrolides (MICs of > or = 0.5 microgram/ml). MICs of RP 59500 (0.5 to 1.0 microgram/ml), RPR 106972 (0.125 to 0.25 microgram/ml), and pyostacine (0.125 to 0.25 microgram/ml) did not alter with the strain's penicillin or macrolide susceptibility status. Three penicillin-susceptible strains and one penicillin-intermediate strain were susceptible to macrolides (MICs of < or = 0.25 microgram/ml); the macrolide MICs for the remaining strains were > or = 4.0 micrograms/ml. Cefotaxime MICs rose with those of penicillin G, but all strains were inhibited at MICs of < or = 2.0 micrograms/ml. RP 59500 was bactericidal for all strains after 24 h at 2 x MIC and yielded 90% killing of all strains at 6 h at 2 x MIC; at 8 x MIC, RP 59500 showed 90% killing of six strains within 10 min (approximately 0.2 h). In comparison, RPR 106972 was bactericidal for 9 of 10 strains at 2 x MIC after 24 h and yielded 90% killing of all strains at 2 x MIC after 6 h; 90% killing of six strains was found at 8 x MIC at 0.2 h. Results for pyostacine were similar to those of RPR 106972. Erythromycin and clarithromycin were bactericidal for three of four macrolide-susceptible strains after 24 h at 4 x MIC. Clarithromycin yielded 90% killing of three strains at 8 x MIC after 12 h. Cefotaxime was bactericidal for all strains after 24 h at 4 x MIC, yielding 90% killing of all strains after 6 h at 4 x MIC. All three streptogramins yielded rapid killing of penicillin- and erythromycin-susceptible and -resistant pneumococci and were the only compounds which killed significant numbers of strains at 0.2 h.
采用肉汤稀释法测定最低抑菌浓度（MIC）以及时间杀菌试验，以检测RP 59500（喹奴普汀-达福普汀）、RPR 106972、派罗星（RP 7293）、红霉素、克拉霉素和头孢噻肟对4株青霉素敏感（MIC为0.008至0.03微克/毫升）、2株青霉素中介（MIC为0.25微克/毫升）和4株青霉素耐药（MIC为2.0至4.0微克/毫升）肺炎球菌菌株的活性：10株菌株中有6株对大环内酯类耐药（MIC≥0.5微克/毫升）。RP 59500（0.5至1.0微克/毫升）、RPR 106972（0.125至0.25微克/毫升）和派罗星（0.125至0.25微克/毫升）的MIC不会因菌株的青霉素或大环内酯类敏感性状态而改变。3株青霉素敏感菌株和1株青霉素中介菌株对大环内酯类敏感（MIC≤0.25微克/毫升）；其余菌株的大环内酯类MIC≥4.0微克/毫升。头孢噻肟的MIC随青霉素G的MIC升高而升高，但所有菌株在MIC≤2.0微克/毫升时均受到抑制。RP 59500在2倍MIC浓度下作用24小时后对所有菌株均有杀菌作用，在2倍MIC浓度下作用6小时后对所有菌株的杀菌率达90%；在8倍MIC浓度下，RP 59500在10分钟（约0.2小时）内对6株菌株的杀菌率达90%。相比之下，RPR 106972在2倍MIC浓度下作用24小时后对10株菌株中的9株有杀菌作用，在2倍MIC浓度下作用6小时后对所有菌株的杀菌率达90%；在8倍MIC浓度下，0.2小时时对6株菌株的杀菌率达90%。派罗星的结果与RPR 106972相似。红霉素和克拉霉素在4倍MIC浓度下作用24小时后对4株大环内酯类敏感菌株中的3株有杀菌作用。克拉霉素在8倍MIC浓度下作用12小时后对3株菌株的杀菌率达90%。头孢噻肟在4倍MIC浓度下作用24小时后对所有菌株均有杀菌作用，在4倍MIC浓度下作用6小时后对所有菌株的杀菌率达90%。所有三种链阳菌素对青霉素和红霉素敏感及耐药的肺炎球菌均有快速杀菌作用，并且是仅有的在0.2小时内就能杀死大量菌株的化合物。
