Filius P M G, van Netten D, Roovers P J E, Vulto A G, Gyssens I C, Verbrugh H A, Endtz H P
Department of Medical Microbiology and Infectious Diseases, Erasmus MC, University Medical Center Rotterdam, Dr Molewaterplein 40, 3015 GD Rotterdam, the Netherlands.
Clin Microbiol Infect. 2003 Sep;9(9):912-8. doi: 10.1046/j.1469-0691.2003.00667.x.
To compare three different chromogenic agars and MacConkey agar for the detection of aerobic Gram-negative bacteria in the normal intestinal microflora and to assess the accuracy of the chromogenic agars for the direct identification of Escherichia coli.
A total of 164 Gram-negative clinical isolates (E. coli, Proteus, Klebsiella, Enterobacter, Morganella and Pseudomonas species) and 30 stool specimens were inoculated in parallel on four media: Chromagar E. coli/Coliform, Chromogenic urinary tract infection UTI medium, CHROMagar Orientation and MacConkey agar. All colonies that differed by color and/or morphology were selected for further identification by VITEK 1 and/or API 20E from each medium.
On E. coli/Coliform agar five out of 32 (16%) E. coli strains failed to produce the color as described by the manufacturer. No remarkable discrepancies were found for the other clinical isolates. There was no significant difference in detection rate (DR) of aerobic Gram-negative bacteria in stool specimens between the different chromogenic agars and MacConkey agar. The overall DR was about 84%, and varied from 100% for monomicrobial specimens to 33% for polymicrobial specimens. The positive predictive values (PPV) for the direct identification of E. coli on Chromagar E. coli/Coliform, Chromogenic UTI medium and CHROMagar Orientation were 1.00, 0.93 and 0.93, respectively. The negative predictive values (NPV) were 0.53, 0.68 and 0.69, respectively.
Chromogenic UTI medium and CHROMagar Orientation are the preferred media because of the higher NPV. The high PPV of these agars allows accurate and rapid identification of E. coli.
比较三种不同的显色培养基和麦康凯琼脂用于检测正常肠道微生物群中的需氧革兰氏阴性菌，并评估显色培养基直接鉴定大肠杆菌的准确性。
将总共164株革兰氏阴性临床分离株（大肠杆菌、变形杆菌、克雷伯菌、肠杆菌、摩根菌和假单胞菌属）和30份粪便标本平行接种于四种培养基：大肠杆菌/大肠菌群显色琼脂、泌尿道感染显色培养基、CHROMagar Orientation培养基和麦康凯琼脂。从每种培养基中选取所有颜色和/或形态不同的菌落，通过VITEK 1和/或API 20E进行进一步鉴定。
在大肠杆菌/大肠菌群琼脂上，32株大肠杆菌中有5株（16%）未产生制造商所述的颜色。其他临床分离株未发现明显差异。不同显色培养基和麦康凯琼脂对粪便标本中需氧革兰氏阴性菌检测率（DR）无显著差异。总体DR约为84%，从单一微生物标本的100%到多微生物标本的33%不等。在大肠杆菌/大肠菌群显色琼脂、泌尿道感染显色培养基和CHROMagar Orientation培养基上直接鉴定大肠杆菌的阳性预测值（PPV）分别为1.00、0.93和0.93。阴性预测值（NPV）分别为0.53、0.68和0.69。
由于较高的NPV，泌尿道感染显色培养基和CHROMagar Orientation培养基是首选培养基。这些琼脂的高PPV允许准确快速地鉴定大肠杆菌。
