Samra Z, Heifetz M, Talmor J, Bain E, Bahar J
Microbiology Department, Rabin Medical Center, Beilinson Campus, Petah Tiqva, Israel.
J Clin Microbiol. 1998 Apr;36(4):990-4. doi: 10.1128/JCM.36.4.990-994.1998.
CHROMagar Orientation, a new chromogenic medium, was evaluated for the detection and differentiation of gram-positive and gram-negative pathogenic microorganisms in 900 urine samples from hospitalized patients. Performance characteristics of the medium were evaluated in comparison to those of 5% sheep blood and MacConkey agars by direct inoculation of the urine samples on the three media. Four gram-negative and two gram-positive strains as well as one yeast control strain from the American Type Culture Collection were used to ensure quality control. CHROMagar Orientation succeeded in detecting all the urine pathogens that were detected by the reference media, including gram-negative bacilli, staphylococci, streptococci, and yeasts. Colony color and morphology on CHROMagar Orientation accurately differentiated Escherichia coli, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, and Acinetobacter spp. Owing to the similarity in the pigmentation produced by Klebsiella, Enterobacter, and Citrobacter isolates, the medium failed to distinguish among them; however, these isolates were easily recognized as coliforms because of their metallic blue coloration. Staphylococci were clearly perceptible: S. aureus and S. epidermidis grow in regular-size colonies that range from opaque white to yellowish, and S. saprophyticus produces opaque pink colonies. All streptococcus strains, including those from groups B and C, were detected. They grow as undifferentiated flat dry diffused colonies, and additional tests were required for identification. Enterococci were easily discriminated by their strong turquoise pigmentation and their typical growth on the agar's surface. Yeast grow in typical creamy wet convex colonies. The accuracy of antibiotic susceptibility determinations according to standard methods was also tested by picking isolates directly from CHROMagar Orientation. The results showed excellent correlation with those obtained with microorganisms picked from reference media. Owing to the ease in differentiating mixed flora on CHROMagar Orientation, antimicrobic susceptibility tests were performed directly from primary isolates in all cases without the need for subcultures.
对一种新型显色培养基CHROMagar Orientation进行了评估，以检测和鉴别住院患者900份尿液样本中的革兰氏阳性和革兰氏阴性致病微生物。通过将尿液样本直接接种到三种培养基上，与5%羊血琼脂和麦康凯琼脂相比较，评估了该培养基的性能特征。使用来自美国模式培养物集存库的4株革兰氏阴性菌、2株革兰氏阳性菌以及1株酵母对照菌株进行质量控制。CHROMagar Orientation成功检测出了参考培养基所检测出的所有尿液病原体，包括革兰氏阴性杆菌、葡萄球菌、链球菌和酵母菌。CHROMagar Orientation上的菌落颜色和形态能够准确区分大肠杆菌、奇异变形杆菌、普通变形杆菌、铜绿假单胞菌和不动杆菌属。由于克雷伯菌属、肠杆菌属和柠檬酸杆菌属分离株产生色素的相似性，该培养基无法区分它们；然而，这些分离株因其金属蓝色而很容易被识别为大肠菌群。葡萄球菌清晰可辨：金黄色葡萄球菌和表皮葡萄球菌形成大小规则的菌落，颜色从不透明白色到淡黄色，腐生葡萄球菌产生不透明粉红色菌落。所有链球菌菌株，包括B组和C组的菌株，均被检测到。它们生长为未分化的扁平干燥扩散菌落，需要进一步检测进行鉴定。肠球菌很容易通过其强烈的蓝绿色色素沉着及其在琼脂表面的典型生长情况进行区分。酵母菌生长为典型的奶油状湿润凸起菌落。还通过直接从CHROMagar Orientation上挑选分离株，测试了根据标准方法进行抗生素敏感性测定的准确性。结果显示与从参考培养基上挑选的微生物所获得的结果具有极好的相关性。由于在CHROMagar Orientation上易于区分混合菌群，所有情况下均直接从原始分离株进行抗菌药敏试验，无需传代培养。
