Kabayiza Jean-Claude, Andersson Maria E, Welinder-Olsson Christina, Bergström Tomas, Muhirwa Gregoire, Lindh Magnus
Department of Infectious Diseases, University of Gothenburg, Gothenburg, Sweden.
BMC Infect Dis. 2013 Sep 27;13:447. doi: 10.1186/1471-2334-13-447.
Molecular diagnostics have emerged as an efficient and feasible alternative for broad detection of pathogens in faeces. However, collection of stool samples is often impractical in both clinical work and in epidemiology studies. The aim of this study was to investigate the diagnostic performance of rectal swabs as compared with traditional faeces samples for detection of enteric agents by PCR.
Three hundred twenty-six pairs of rectal swab and stool samples, obtained from Rwandan children aged 0.5-4.99 years, with or without diarrhoea, were analysed by multiple real-time PCR amplifying 3 viral, 6 bacterial and one protozoan target.
For all agents there was a significant correlation (R2 0.31-0.85) between Ct values in faeces and rectal swabs. For most agents the Ct values, a marker for target concentration, were significantly lower (by 1-3 cycles) in faeces, indicating pathogen content up to ten times higher than in rectal swabs. Despite this, there was no significant difference in detection rate between faeces and rectal swabs for any agent, reflecting that pathogen concentration was far above the limit of detection in the majority of cases.
The similar detection rates and the Ct value correlations as compared with traditional faeces samples indicate that rectal swabs are accurate for real-time PCR-based identification of enteric agents and may be used also for quantitative estimation of pathogen load.
分子诊断已成为一种高效且可行的替代方法，可广泛检测粪便中的病原体。然而，在临床工作和流行病学研究中，粪便样本的采集往往不切实际。本研究的目的是通过聚合酶链反应（PCR），调查直肠拭子与传统粪便样本相比，在检测肠道病原体方面的诊断性能。
从0.5至4.99岁的卢旺达儿童中获取326对直肠拭子和粪便样本，这些儿童有或没有腹泻症状，通过多重实时PCR对3种病毒、6种细菌和1种原生动物靶点进行分析。
对于所有病原体，粪便和直肠拭子中的Ct值之间存在显著相关性（R²为0.31 - 0.85）。对于大多数病原体，作为靶点浓度标志物的Ct值在粪便中显著更低（低1 - 3个循环），表明病原体含量比直肠拭子中高至10倍。尽管如此，对于任何病原体，粪便和直肠拭子之间的检出率没有显著差异，这反映出在大多数情况下病原体浓度远高于检测限。
与传统粪便样本相比，相似的检出率和Ct值相关性表明，直肠拭子对于基于实时PCR的肠道病原体鉴定是准确的，并且也可用于病原体载量的定量估计。
