Clonal Diversification and Changes in Lipid Traits and Colony Morphology in Mycobacterium abscessus Clinical Isolates
Clonal Diversification and Changes in Lipid Traits and Colony Morphology in Mycobacterium abscessus Clinical Isolates
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DOI：
10.1128/jcm.02015-15
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发表时间：
2015-11-01
影响因子：
9.4
通讯作者：
Zelazny, Adrian M.
中科院分区：
文献类型：
--
作者：
Park, In Kwon;Hsu, Amy P.;Zelazny, Adrian M.
在囊性纤维化（CF）患者中，脓肿分枝杆菌从光滑到粗糙的菌落形态转变与糖肽类脂（GPL）的丧失、致病性的增加和临床衰退有关。然而，进化表型和遗传变化仍然不清楚。对9例非cf持续性脓肿分枝杆菌感染患者的连续分离株进行菌落形态、脂质谱（薄层色谱法和基质辅助激光解吸电离飞行时间质谱法）、GPL位点8个基因测序和复杂脂质生物合成关键基因fadD23的表达水平分析。所有50株分离株均被分型为脓肿分枝杆菌亚种，并在每位患者中具有无性相关。粗糙的分离株都缺乏GPL，在疾病后期占主导地位，有些在粗糙形态中表现出变异。虽然大多数（77%）粗分离株在mps1和mps2中含有有害突变，但13%在mmpL4a和mmpS4中显示出以前未报道的突变，后者产生假定的GPL前体。两个分离株在测序的8个基因中没有显示出任何有害突变。在5例患者中检测到含有不同GPL位点突变的混合群体，显示出克隆多样化，这可能被传统的抗酸杆菌（AFB）培养方法所忽视。我们的工作重点是MALDI-TOF MS在鉴定之外的应用，重点是与毒力和适应相关的分枝杆菌脂质。后来的分离株表现出甘油三酯的积累和fadD23的表达减少，有时在粗糙的菌落开始之前。我们的研究结果表明，在脓肿分枝杆菌慢性肺部感染期间，克隆多样化和脂质代谢的转变，包括GPL的丧失，发生了。GPL损失本身可能无法解释与粗糙形态相关的所有特征。
The smooth-to-rough colony morphology shift in Mycobacterium abscessus has been implicated in loss of glycopeptidolipid (GPL), increased pathogenicity, and clinical decline in cystic fibrosis (CF) patients. However, the evolutionary phenotypic and genetic changes remain obscure. Serial isolates from nine non-CF patients with persistent M. abscessus infection were characterized by colony morphology, lipid profile via thin-layer chromatography and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), sequencing of eight genes in the GPL locus, and expression level of fadD23, a key gene involved in the biosynthesis of complex lipids. All 50 isolates were typed as M. abscessus subspecies abscessus and were clonally related within each patient. Rough isolates, all lacking GPL, predominated at later disease stages, some showing variation within rough morphology. While most (77%) rough isolates harbored detrimental mutations in mps1 and mps2, 13% displayed previously unreported mutations in mmpL4a and mmpS4, the latter yielding a putative GPL precursor. Two isolates showed no deleterious mutations in any of the eight genes sequenced. Mixed populations harboring different GPL locus mutations were detected in 5 patients, demonstrating clonal diversification, which was likely overlooked by conventional acid-fast bacillus (AFB) culture methods. Our work highlights applications of MALDI-TOF MS beyond identification, focusing on mycobacterial lipids relevant in virulence and adaptation. Later isolates displayed accumulation of triacylglycerol and reduced expression of fadD23, sometimes preceding rough colony onset. Our results indicate that clonal diversification and a shift in lipid metabolism, including the loss of GPL, occur during chronic lung infection with M. abscessus. GPL loss alone may not account for all traits associated with rough morphology.