Okumu A, McCarthy K, Orwa J, Williamson J, Musau S, Alexander H, Cavanaugh S, Modi S, Cain K
Kenya Medical Research Institute (KEMRI) Center for Global Health Research, Kisumu, Kenya.
Division of Tuberculosis Elimination (DTBE), CDC, Atlanta, GA.
J Med Sci Clin Res. 2017;5(8). doi: 10.18535/jmscr/v5i8.86.
While molecular methods have been recently endorsed for diagnosis of tuberculosis (TB), mycobacterial culture remains the gold standard. Lowenstein-Jensen (LJ) is often used for the cultivation of Mycobacterium tuberculosis complex (MTBC); however contamination often renders a subset of cultures useless. We compared the MTBC yield and contamination rate of processed sputum inoculated on LJ with antibiotics (LJ PACT) to LJ without antibiotics (LJ).
Sputum samples were obtained from people living with HIV enrolled in a TB screening study in western Kenya, processed using NALC/NaOH-Na citrate, then inoculated on LJ PACT and LJ media. Cultures were evaluated weekly with growth identified as acid-fast bacilli by Ziehl-Neelsen bright-field microscopy. MTBC and nontuberculous mycobacteria (NTM) were identified by immunochromatographic and line probe assays.
A total of 700 sputum samples were cultured on both LJ PACT and LJ between March and June 2012. Of those cultured on LJ PACT, 29 (4.1%) grew MTBC, 613 (87.6%) were negative, 12 (1.7%) grew NTM, and 46 (6.6%) were contaminated; on LJ, 28 (4%) grew MTBC, 553 (79%) were negative, 9 (1.3%) grew NTM, and 110 (15.7%) were contaminated. The difference in contamination on LJ PACT and LJ was statistically significant (p<0.0001), while the difference in MTBC growth was not (p=0.566).
尽管最近分子方法已被认可用于结核病（TB）的诊断，但分枝杆菌培养仍然是金标准。罗-琴（LJ）培养基常用于结核分枝杆菌复合群（MTBC）的培养；然而，污染常常导致一部分培养物无用。我们比较了接种有抗生素的LJ培养基（LJ PACT）和无抗生素的LJ培养基上处理过的痰液中MTBC的产量和污染率。
痰标本取自参与肯尼亚西部一项结核病筛查研究的HIV感染者，使用NALC/NaOH-柠檬酸钠进行处理，然后接种在LJ PACT和LJ培养基上。每周对培养物进行评估，通过齐-尼氏亮视野显微镜将生长物鉴定为抗酸杆菌。通过免疫色谱法和线性探针分析鉴定MTBC和非结核分枝杆菌（NTM）。
2012年3月至6月期间，共在LJ PACT和LJ培养基上培养了700份痰标本。在LJ PACT上培养的标本中，29份（4.1%）生长出MTBC，613份（87.6%）为阴性，12份（1.7%）生长出NTM，46份（6.6%）被污染；在LJ培养基上，28份（4%）生长出MTBC，553份（79%）为阴性，9份（1.3%）生长出NTM，110份（15.7%）被污染。LJ PACT和LJ培养基上污染情况的差异具有统计学意义（p<0.0001），而MTBC生长情况的差异无统计学意义（p=0.566）。
