Background

The revised national guidelines for analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage (UK) provide an objective means of assessing cerebrospinal fluid (CSF) samples to determine risk of subarachnoid haemorrhage (SAH). The guidelines are intended for general use, but samples rendered uninterpretable due to the presence of the antibiotic doxycycline have been described. Here, further cases of antibiotic- based interference, and their implications, are presented.

Methods

An archival search of CSF spectra performed at Hallands County Hospital Halmstad was performed for the years 2011 and 2016- 2019 in an attempt to locate instances of interference. Each case of suspected interference was further investigated with in vitro reproduction experiments as a means of confirmation and assessment of potential clinical impact.

Results

A total of 10 cases of CSF curve interference were discovered: 6 due to doxycycline, 3 due to metronidazole and 1 due to tetracycline. Interference due to the tetracycline class was revealed through in vitro experimentation to cause an apparent decrease in the sample’s net bilirubin absorbance(NBA); the presence of xanthochromia on visual inspection was, however, conserved.

Conclusions

The problem of CSF absorbance curve interference might be more common than previously suspected. Due to the potential NBA- lowering effect of tetracyclines, the author recommends visual examination of CSF samples in every case.

背景

修订后的疑似蛛网膜下腔出血患者脑脊液胆红素分析指南（英国）为评估脑脊液 (CSF) 样本以确定蛛网膜下腔出血 (SAH) 的风险提供了一种客观手段。该指南旨在供一般使用，但由于抗生素强力霉素的存在，样本变得无法解释。此处介绍了更多基于抗生素的干扰案例及其影响。

方法

2011 年和 2016-2019 年在哈兰兹县医院哈尔姆斯塔德进行的脑脊液光谱档案搜索，试图定位干扰实例。每个疑似干扰病例都通过体外繁殖实验进一步调查，作为确认和评估潜在临床影响的手段。

结果

共发现CSF曲线干扰10例：强力霉素6例，甲硝唑3例，四环素1例。通过体外实验揭示了四环素类的干扰导致样品的净胆红素吸光度（NBA）明显下降；然而，目视检查中黄变的存在是保守的。

结论

CSF 吸光度曲线干扰的问题可能比以前怀疑的更常见。由于四环素的潜在 NBA 降低作用，作者建议在每种情况下对 CSF 样本进行目视检查。