Owusu Enid, Newman Mercy Jemima, Akumwena Amos, Ofosu-Appiah Lawrence, Pluschke Gerd
School of Biomedical and Allied Health Sciences, University of Ghana, Ghana.
University of Ghana Medical School, Ghana.
Int J Mycobacteriol. 2015 Sep;4(3):184-90. doi: 10.1016/j.ijmyco.2015.03.003. Epub 2015 Jun 6.
Buruli ulcer (BU) disease, a skin condition caused by Mycobacterium ulcerans (M. ulcerans) is endemic in remote rural areas. Disease diagnosis on clinical basis alone can be misleading, requiring definitive diagnosis based on laboratory tests. Resource constraints in BU endemic areas make microscopy for the detection of acid fast bacilli (AFB) an important and useful method. It is rapid, user-friendly, convenient and cheap. Despite its usefulness, its performance is relatively low. This study investigated modifications of the current method aimed at improving its performance. Forty (IS) 2404 polymerase chain reactions (PCR) positive BU samples were processed by eight physical (centrifugation and overnight sedimentation) and chemical (phenol ammonium sulphate and sodium hypochlorite) modifications of the current direct method. Assessments were based on standard AFB evaluation coupled with in house criteria; positivity (P), clarity and contrast (C) release of bacilli from specimen (R). Overall AFB positivity rate was 64% (409/640). Each protocol had 80 smears. The percentage positivity (P) for the conventional method was 58% (46/80) smears. The highest positivity rate of 57/80 (%) was by protocol 7 (5% phenol in 4% ammonium sulphate (PhAS) and concentrated by overnight gravitational sedimentation). The least positivity rate at 35% (28/80) was by protocol 1 (smears from direct application of swab tips). The differences in performance between the two chemical tested; 5% phenol in 4% ammonium sulphate (PhAS) and 3.5% NaHOCl was significant (p<0.05). The differences between the two physical methods were however not significant (p>0.05). This study concluded that BU samples treated with a solution of 5% phenol in 4% ammonium sulphate and concentrated by either centrifugation or overnight sedimentation is useful for maximizing AFB detection by bright field microscopy. This can be useful in rural health facilities with resource constraints.
布氏溃疡（BU）病是由溃疡分枝杆菌引起的一种皮肤病，在偏远农村地区呈地方性流行。仅基于临床进行疾病诊断可能会产生误导，需要基于实验室检测来进行明确诊断。布氏溃疡流行地区的资源限制使得通过显微镜检测抗酸杆菌（AFB）成为一种重要且实用的方法。它快速、对用户友好、方便且成本低廉。尽管其有用性，但该方法的检测效能相对较低。本研究调查了对当前方法的改进措施，旨在提高其检测效能。对40份经（IS）2404聚合酶链反应（PCR）检测呈阳性的布氏溃疡样本，采用当前直接法的8种物理（离心和过夜沉淀）和化学（酚硫酸铵和次氯酸钠）改进方法进行处理。评估基于标准AFB评估并结合内部标准；阳性率（P）、清晰度和对比度（C）以及从标本中释放出杆菌的情况（R）。总体AFB阳性率为64%（409/640）。每个方案制作80张涂片。传统方法的阳性涂片百分比（P）为58%（46/80）。阳性率最高的是方案7（4%硫酸铵中含5%苯酚（PhAS）并通过过夜重力沉淀浓缩），为57/80（%）。阳性率最低的是方案1（直接用拭子尖端涂片），为35%（28/80）。所测试的两种化学方法；4%硫酸铵中含5%苯酚（PhAS）和3.5%次氯酸钠之间的性能差异具有显著性（p<0.05）。然而，两种物理方法之间的差异不具有显著性（p>0.05）。本研究得出结论，用4%硫酸铵中含5%苯酚的溶液处理布氏溃疡样本，并通过离心或过夜沉淀进行浓缩，有助于通过明视野显微镜最大限度地检测AFB。这对于资源有限的农村卫生机构可能有用。
