Effects of culture media on detection of methicillin resistance in Staphylococcus aureus and coagulase negative staphylococci by disc diffusion methods.
Effects of culture media on detection of methicillin resistance in Staphylococcus aureus and coagulase negative staphylococci by disc diffusion methods.
复制标题
培养基对纸片扩散法检测金黄色葡萄球菌和凝固酶阴性葡萄球菌甲氧西林耐药性的影响。
DOI：
--
复制
发表时间：
1993
影响因子：
3.4
通讯作者：
J. Selkon
中科院分区：
文献类型：
--
作者：
L. Milne;M. Crow;A. Emptage;J. Selkon
目的：用纸片扩散法检测10种培养基检出葡萄球菌对甲氧西林的耐药性和敏感性。方法：对50株金黄色葡萄球菌和135株凝固酶阴性葡萄球菌进行了哥伦比亚试验、诊断敏感性试验、Mueller-Hinton试验、Sensitest试验和等敏琼脂试验。在孵育18小时和40小时后进行培养。记录区域的直径及其特征，并评估这些介质产生清晰、可读的抑制区域的能力。研究了决定抗性的变量的变化。结果分析允许区域直径减少8 mm和10 mm与对照相比，除了标准的6 mm。结果--加入氯化钠的哥伦比亚琼脂支持所有菌株的生长，检测到最多的耐药菌株，并且是最容易阅读的。大多数耐药株在18小时后检测到耐药性，但有些需要40小时的孵育。然而，对于敏感菌株，纸片扩散法和参考MIC法之间的符合率很低(63-94%)。允许更大的区带缩小导致与敏感菌株的更一致，但因此降低了对耐药菌株的检测。其他媒体显示了一些增长失败和更多难以阅读的区域。当培养时间延长到40h时，检测到更多的抗性，但这始终低于在哥伦比亚琼脂中添加盐的情况。结论--所有的耐药菌株均未被检测到。在这方面，添加盐的哥伦比亚琼脂是最令人满意的，但它误判了高达37%的敏感菌株为抗性。纸片扩散法检测甲氧西林不可靠。
AIMS--To test 10 culture media for their ability to detect resistance and sensitivity of staphylococci to methicillin by disc diffusion. METHODS--Fifty strains of Staphylococcus aureus and 135 strains of coagulase negative staphylococci were tested using Columbia, Diagnostic Sensitivity Test, Mueller Hinton, Sensitest and Iso-sensitest agars with and without 5% added sodium chloride. Cultures were examined after 18 and 40 hours of incubation. The diameter of the zone and its characteristics were recorded and these media were assessed for their ability to produce clear, readable zones of inhibition. Changes in the variables which determined resistance were investigated. Results were analysed allowing a zone diameter reduction of 8 mm and 10 mm compared with the control in addition to the standard 6 mm. RESULTS--Columbia agar with added sodium chloride supported the growth of all strains, detected the highest number of resistant strains, and was the easiest to read. Resistance was detected after 18 hours in most resistant strains, but some required 40 hours of incubation. There was poor agreement, however, on this medium (63-94%) between disc diffusion and the reference MIC method for sensitive strains. Allowing a greater reduction in zone size resulted in more agreement with sensitive strains but with consequently lowered detection of resistant strains. The other media showed some growth failures and more zones that were difficult to read. More resistance was detected when incubation was prolonged to 40 hours but this was consistently less than on Columbia agar with added salt. CONCLUSIONS--None of the media detected all of the resistant strains. Columbia agar with added salt was the most satisfactory medium in this respect, but it misidentified up to 37% of the sensitive strains as resistant. Methicillin susceptibility testing by disc diffusion testing is unreliable.