Jorgensen J H, Skweres J A, Mishra S K, McElmeel M L, Maher L A, Mulder R, Lancaster M V, Pierson D L
Department of Pathology, University of Texas Health Science Center, San Antonio 78284-7750, USA.
J Clin Microbiol. 1997 Aug;35(8):2093-7. doi: 10.1128/jcm.35.8.2093-2097.1997.
Very little is known regarding the effects of the microgravity environment of space flight upon the action of antimicrobial agents on bacterial pathogens. This study was undertaken to develop a simple method for conducting antibacterial susceptibility tests during a space shuttle mission. Specially prepared susceptibility test research cards (bioMérieux Vitek, Hazelwood, Mo.) were designed to include 6 to 11 serial twofold dilutions of 14 antimicrobial agents, including penicillins, cephalosporins, a beta-lactamase inhibitor, vancomycin, erythromycin, tetracycline, gentamicin, ciprofloxacin, and trimethoprim-sulfamethoxazole. MICs of the drugs were determined by visual reading of color end points in the Vitek research cards made possible by incorporation of a colorimetric growth indicator (alamarBlue; Accumed International, Westlake, Ohio). This study has demonstrated reproducible susceptibility results in the testing of isolates of Staphylococcus aureus, group A Streptococcus species, Enterococcus faecalis, Escherichia coli (beta-lactamase-positive and -negative strains), Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa. In some instances, the MICs were comparable to those determined by a standard broth microdilution method, while in some cases the unique test media and format yielded slightly different values that were themselves reproducible. The proposed in-flight experiment will include inoculation of the Vitek cards on the ground prior to launch of the space shuttle, storage of inoculated cards at refrigeration temperature aboard the space shuttle until experiment initiation, and then incubation of the cards for 18 to 48 h prior to visual interpretation of MICs by the mission's astronauts. Ground-based studies have shown reproducible MICs following storage of inoculated cards for 7 days at 4 to 8 degrees C to accommodate the mission's time schedule and the astronaut's activities. For comparison, ground-based control (normal gravity) MIC values will be generated by simultaneous inoculation and incubation of a second set of test cards in a laboratory at the launch site. This procedure can provide for a safe and compact experiment that should yield new information on the effects of microgravity on the biological activities of various classes of antibiotics.
关于太空飞行的微重力环境对抗菌药物作用于细菌病原体的影响，目前所知甚少。本研究旨在开发一种在航天飞机任务期间进行抗菌药敏试验的简单方法。专门制备的药敏试验研究卡（生物梅里埃Vitek，密苏里州黑兹尔伍德）设计包含14种抗菌药物的6至11个系列两倍稀释液，这些抗菌药物包括青霉素、头孢菌素、一种β-内酰胺酶抑制剂、万古霉素、红霉素、四环素、庆大霉素、环丙沙星以及甲氧苄啶-磺胺甲恶唑。通过加入比色生长指示剂（alamarBlue；Accumed International，俄亥俄州西湖），在Vitek研究卡中通过目视读取颜色终点来确定药物的最低抑菌浓度（MIC）。本研究已证明，在对金黄色葡萄球菌、A组链球菌属、粪肠球菌、大肠杆菌（β-内酰胺酶阳性和阴性菌株）、肺炎克雷伯菌、阴沟肠杆菌和铜绿假单胞菌的分离株进行测试时，药敏结果具有可重复性。在某些情况下，MIC与通过标准肉汤微量稀释法测定的结果相当，而在某些情况下，独特的试验培养基和形式产生的数值略有不同，但这些数值本身具有可重复性。拟进行的飞行实验将包括在航天飞机发射前在地面接种Vitek卡，将接种后的卡片在航天飞机上冷藏温度下储存，直到实验开始，然后在任务宇航员目视解读MIC之前将卡片孵育18至48小时。地面研究表明，为适应任务时间表和宇航员活动，接种后的卡片在4至8摄氏度下储存7天后，MIC具有可重复性。为作比较，将在发射地点的实验室中同时接种和孵育第二组测试卡，以生成地面对照（正常重力）MIC值。该程序可以提供一个安全且紧凑的实验，有望产生关于微重力对各类抗生素生物活性影响的新信息。
