Jorgensen J H, McElmeel M L
Department of Pathology, University of Texas Health Science Center, San Antonio 78284-7750, USA.
J Antimicrob Chemother. 1997 May;39 Suppl A:69-73. doi: 10.1093/jac/39.suppl_1.69.
Quinupristin/dalfopristin is an injectable streptogramin antibiotic that is constituted in a 30:70 (w/w) ratio of the two components. Quinupristin and dalfopristin are thought to act synergically by binding to two separate sites on the bacterial 50S ribosomal subunit. The in-vitro activities of the two components separately and together in different ratios were determined for a collection of 100 Haemophilus influenzae strains representing various antimicrobial resistance phenotypes. The NCCLS microdilution susceptibility testing procedure incorporating Haemophilus test medium (HTM) broth was used to determine MICs of quinupristin, dalfopristin and seven other antimicrobial agents. The MIC50 and MIC90 values were 4 and 8, 4 and 16, and 64 and 128 mg/L for quinupristin/dalfopristin (30:70), dalfopristin and quinupristin, respectively. MICs of quinupristin and dalfopristin were also determined in Mueller-Hinton lysed horse blood broth and by HTM agar dilution testing. Compared with HTM broth-derived results, the MICs of quinupristin/dalfopristin and its components were the same or one dilution higher in lysed horse blood and HTM agar incubated in air, and were equivalent or one dilution lower in HTM agar incubated in a CO2 atmosphere. The MICs of quinupristin and dalfopristin separately or together were directly proportional to erythromycin MICs, but were otherwise unaffected by any of the resistance mechanisms represented in these strains. MICs of quinupristin and dalfopristin combined in ratios of 10:90, 70:30 and 90:10 did not differ significantly from those of the 30:70 ratio. Thus, unlike the synergic activity noted against Gram-positive bacteria, the activity of quinupristin/dalfopristin against H. influenzae appears to be due almost entirely to the dalfopristin component of the combination.
奎奴普丁/达福普汀是一种注射用链阳菌素类抗生素，由两种成分按30:70（重量/重量）的比例组成。奎奴普丁和达福普汀被认为通过结合细菌50S核糖体亚基上的两个不同位点发挥协同作用。对于代表各种抗菌药物耐药表型的100株流感嗜血杆菌菌株，分别测定了两种成分单独以及以不同比例混合时的体外活性。采用包含嗜血杆菌测试培养基（HTM）肉汤的NCCLS微量稀释药敏试验程序，来测定奎奴普丁、达福普汀及其他七种抗菌药物的最低抑菌浓度（MIC）。奎奴普丁/达福普汀（30:70）、达福普汀和奎奴普丁的MIC50值分别为4mg/L、4mg/L和64mg/L，MIC90值分别为8mg/L、16mg/L和128mg/L。还在Mueller-Hinton溶解马血肉汤中以及通过HTM琼脂稀释试验测定了奎奴普丁和达福普汀的MIC。与HTM肉汤得出的结果相比，在空气中孵育的溶解马血和HTM琼脂中，奎奴普丁/达福普汀及其成分的MIC相同或高一个稀释度，而在二氧化碳气氛中孵育的HTM琼脂中，MIC相等或低一个稀释度。奎奴普丁和达福普汀单独或联合使用时的MIC与红霉素MIC成正比，但不受这些菌株中所代表的任何耐药机制的影响。以10:90、70:30和90:10比例组合的奎奴普丁和达福普汀的MIC与30:70比例的MIC没有显著差异。因此，与对革兰氏阳性菌所观察到的协同活性不同，奎奴普丁/达福普汀对流感嗜血杆菌的活性似乎几乎完全归因于该组合中的达福普汀成分。
