Background

In microbiological diagnosis of periprosthetic joint infection (PJI) there is much controversial discussion about culture media and incubation time, especially if anaerobic bacteria are the causative agents. This retrospective analysis was conducted to compare the results obtained by inoculation of sonicate fluid from prosthetic components into BD Bactec blood culture bottles with those obtained by our culture method using sensitive supplemented growth media.

Methods

Twenty-eight cases were included in this study. For definition of PJI, the criteria of the Musculoskeletal Infection Society (MSIS) were considered. The quantity and time to positivity of anaerobes detected in sonicate fluid were monitored both from inoculated supplemented liver thioglycollate broth and anaerobic blood culture bottles. Furthermore, phenotypic testing was performed on the antimicrobial activity within the sonicate fluid.

Results

The most frequently isolated microbes were Cutibacterium species, followed by Finegoldia magna, Parvimonas micra, Robinsoniella peoriensis, Clostridium species, Peptoniphilus harei and Slackia exigua. In 24 cases, the microorganisms became detectable within five days (median time 3.2 days) when sonicate fluid was incubated in supplemented liver thioglycollate broth, regardless of whether the patients had taken antimicrobial agents prior to surgery. However, when sonicate fluid was inoculated into anaerobic Bactec bottles, the median time to positivity was 7.4 days and only 12 cases (43%) were correctly identified. Sixteen cases remained negative after 14 days of incubation.

Conclusion

Depending on the pathogen, incubation of sonicate fluid using blood culture bottles can support diagnosis of PJI but compared with our culture medium it is less efficient if anaerobes are the suspected cause of infection. Microbiological expertise is therefore indispensable to ensure reliable detection of these microorganisms in PJI until a gold standard for laboratory handling of anaerobes has been established.

中文翻译：

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接种到血液培养瓶中的超声液体不能改善厌氧菌引起的假体周围关节感染的诊断。回顾性分析。

背景

在人工修复假体周围关节感染（PJI）的微生物学诊断中，有关培养基和孵育时间的争议颇多，特别是如果厌氧菌是病原体的话。进行此回顾性分析，以比较通过将假体组件中的超声处理液接种到BD Bactec血液培养瓶中所获得的结果与通过我们的使用敏感的补充生长培养基的培养方法所获得的结果进行比较。

方法

这项研究包括28例。对于PJI的定义，考虑了肌肉骨骼感染学会（MSIS）的标准。从接种的补充肝硫代乙醇酸肉汤和厌氧血培养瓶中监测在超声液中检测到的厌氧菌阳性的数量和时间。此外，对超声液中的抗菌活性进行了表型测试。

结果

分离最频繁的微生物是角皮杆菌菌种，其次是大花小金枪鱼，帕尔克莫纳斯微囊菌，罗宾逊菌，梭状芽孢杆菌，哈密棉杆菌和Slackia exigua。在24例患者中，将超声处理液在补充的巯基乙醇酸肝素培养液中孵育后的五天内（中位时间为3.2天），无论患者在手术前是否已服用抗微生物剂，均可检测到微生物。但是，当将超声处理液接种到厌氧Bactec瓶中时，阳性的中位时间为7.4天，只有12例（43％）被正确识别。孵育14天后，仍有16例阴性。

结论

根据病原体，使用血液培养瓶孵育超声液可以支持PJI的诊断，但是与我们的培养基相比，如果怀疑厌氧菌是引起感染的原因，效率较低。因此，直到建立了实验室处理厌氧菌的金标准，微生物专业知识对于确保可靠地检测PJI中的这些微生物都是必不可少的。