Kenny J F, Isburg C D, Michaels R H
Pediatrics. 1980 Jul;66(1):14-6.
A strain of Haemophilus influenzae type b with considerable resistant to both ampicillin and chloramphenicol was recovered from a South Dakota child with meningitis. There was an initial lack of response to conventional doses but the child improved after a brief period of 200 mg/kg/day of chloramphenicol. The organism showed in vitro resistance to ampicillin, carbenicillin, tetracycline, and chloramphenicol (for each antibiotic the minimal inhibitory concentration (MIC) was 8 micrograms/ml or greater with a bacterial challenge of 10(5) colony-forming units (CFU)/ml), but it was sensitive to both streptomycin and rifampin (MIC 1.6 micrograms/ml, respectively). Isobolograms constructed from the results of testing various concentrations of ampicillin and chloramphenicol showed additive effects with high bacterial inocula (10(5) or 10(7) CFU/ml), but antagonism with low inocula (10(2) or 10(4) CFU/ml).
从南达科他州一名患脑膜炎的儿童身上分离出一株对氨苄西林和氯霉素均具有相当耐药性的b型流感嗜血杆菌。起初对常规剂量无反应，但在给予200mg/kg/天的氯霉素治疗一段时间后患儿病情有所改善。该菌株在体外对氨苄西林、羧苄西林、四环素和氯霉素耐药（对于每种抗生素，在细菌接种量为10⁵集落形成单位（CFU）/ml时，最小抑菌浓度（MIC）为8微克/毫升或更高），但对链霉素和利福平敏感（MIC分别为1.6微克/毫升）。根据不同浓度氨苄西林和氯霉素的测试结果构建的等效线图显示，在高细菌接种量（10⁵或10⁷CFU/ml）时呈现相加作用，但在低接种量（10²或10⁴CFU/ml）时呈现拮抗作用。
