Washington J A, Snyder R J, Kohner P C, Wiltse C G, Ilstrup D M, McCall J T
J Infect Dis. 1978 Feb;137(2):103-11. doi: 10.1093/infdis/137.2.103.
Fifty-five strains of Pseudomonas aeruginosa were tested against arithmetic increments in concentrations of gentamicin, tobramycin, and amikacin in 14 different lots of Mueller-Hinton agar. The divalent cation content of each lot was determined by atomic absorption spectrometry. The relation between mean minimal inhibitory concentration (MIC) for strains within each lot and cation content was studied by stepwise regression. Among the cations, the content of Zn++ most highly correlated with the MIC of each aminoglycoside; however, Zn++ accounted for only 23%, 60%, and 47% of the variability in the mean MIC of gentamicin, tobramycin, and amikacin, respectively, against all strains. In two-cation models Zn++ with Ca++ or Cu++ was most highly correlated with the mean MICs of the three aminoglycosides against all strains. No divalent cation, either singly or in combination with one or two other cations, gave a good prediction of the MICs of the aminoglycosides in agar. Furthermore, there was variability in the cations that most highly correlated with the MICs for some strains. These observations support the concept that ionic strength, cations, and a variety of other as yet poorly defined components of media influence the activity of aminoglycosides against P. aeruginosa.
在14种不同批次的穆勒-欣顿琼脂中，对55株铜绿假单胞菌进行了庆大霉素、妥布霉素和阿米卡星浓度呈算术递增的测试。通过原子吸收光谱法测定每一批次的二价阳离子含量。采用逐步回归法研究了每一批次菌株的平均最低抑菌浓度（MIC）与阳离子含量之间的关系。在这些阳离子中，Zn++的含量与每种氨基糖苷类药物的MIC相关性最高；然而，Zn++分别仅占所有菌株对庆大霉素、妥布霉素和阿米卡星平均MIC变异性的23%、60%和47%。在双阳离子模型中，Zn++与Ca++或Cu++组合时，与所有菌株对三种氨基糖苷类药物的平均MIC相关性最高。无论是单一的二价阳离子，还是与一种或两种其他阳离子组合，都不能很好地预测琼脂中氨基糖苷类药物的MIC。此外，与某些菌株的MIC相关性最高的阳离子存在变异性。这些观察结果支持这样一种观点，即离子强度、阳离子以及培养基中各种其他尚未明确界定的成分会影响氨基糖苷类药物对铜绿假单胞菌的活性。
