Study of virulence and drug-susceptabiltly of MAC strains isolated from Japanese patients with the nodular-bronchiectasis type MAC disease

最近，在没有明显危险因素的患者中观察到越来越多的鸟分枝杆菌复合体（MAC）肺病病例，例如有酗酒和重度吸烟史的男性中的上叶空洞病。患者主要是老年女性，无吸烟史，网状结节浸润，有斑片状双侧支气管扩张，常规累及右中叶和小舌。这种结节性支气管扩张（NB）型MAC肺部感染目前在日本呈上升趋势。虽然这种MAC疾病的危险因素主要归因于宿主方面的条件，例如经常洗澡的人严重暴露于MAC病原体以及女性肺部解剖结构和生理功能的特殊性。目前尚不清楚是否有MAC人群优先引起结节性支气管扩张（NB）型MAC肺病，而不是引起MAC疾病， ...更多信息 肺结核（TB）上叶空洞性病变多见于男性，称为TB型MAC病。在这里，我们研究了从日本NB型MAC疾病（NB-MAC）患者中分离的MAC菌株的毒力和药物敏感性，并与从日本TB型MAC疾病（TB-MAC）患者中分离的MAC菌株进行了比较。将NB-MAC和TB-MAC各5株与其他组进行比较，以了解它们在各种类型的人源培养细胞中的侵袭力和细胞内复制能力，包括3种巨噬细胞系和1种肺泡上皮细胞系和1种支气管上皮细胞系。获得了以下结果。(1)在人巨噬细胞系，如THP-1和MM 6巨噬细胞中，NB-MAC菌株比TB-MAC菌株复制得更快，尽管这种差异不显著。(2)在U937鼠巨噬细胞系内，NB-MAC和TB-MAC之间的细胞内生长速率没有观察到差异。(3)在A549人II型肺泡上皮细胞系内部，NB-MAC菌株的细胞内生长比TB-MAC菌株稍微更旺盛。(4)NB-MAC和TB-MAC菌株均显示出类似的内化到NL 20人支气管上皮细胞系中并在NL 20细胞内进行细胞内复制的能力。(5)在细胞外环境中，如在7 HSF培养基中，NB-MAC比TB-MAC生长更快。(6)NB-和TB-MAC菌株均诱导THP-1巨噬细胞在细菌内化后产生活性氧中间体和活性氮中间体。这两种类型的MAC生物体在诱导这些抗微生物效应分子的巨噬细胞产生方面显示出相同的功效。(7)NB-和TB-MAC菌株对一些抗分枝杆菌药物如利福平（RFP）、氟喹诺酮类和异烟肼（INH）的药物敏感性彼此相当不同，如下所示。NB-MAC<60>对RFP和氟喹诺酮类药物（左氧氟沙星、加替沙星、西他沙星）的敏感性是TB-MAC的4倍，对INH的敏感性是TB-MAC的2倍。两种MAC对其他试验药物的敏感性水平相同，包括大环内酯类（克拉霉素、阿奇霉素）、利福昔单抗、乙胺丁醇和氨基糖苷类（链霉素、阿米卡星）。目前的调查结果表明：首先，在对宿主巨噬细胞和肺上皮细胞的感染性的基础上，从NB-MAC疾病分离的MAC菌株和从TB-MAC疾病分离的MAC菌株之间的毒力可能没有本质差异。第二，这两种类型的MAC分离株的药物敏感性可能存在一定程度的差异，特别是在RFP、氟喹诺酮类和INH的情况下，从而表明使用这些药物治疗MAC患者的临床输出可能不同于NB型疾病患者与TB I型患者。少

There are recently observed increasing cases of Mycobacterium avium complex (MAC) lung disease in patients with no apparent risk factors, such as upper lobe cavitary disease in the male with a history of alcohol and heavy cigarette abuse. The patients are primarily elderly women with no history of smoking, and reticulonodular infiltrates and have patchy bilateral bronchiectasis, with routine involvement of the right middle lobe and lingula. This nodular-bronchiectasis (NB) type MAC pulmonary infection is currently increasing in Japan. Although the risk factors for such MAC diseases are primarily attributable to host-side conditions, such as severe exposure to MAC pathogens in persons frequently taking shower bath and the peculiarity in the anatomical structure and physiological function of woman's lungs. At present, it is unclear whether or not there are MAC populations which preferentially cause nodular-bronchiectasis (NB) type MAC lung disease rather than causing MAC disease that mim … More ics tuberculosis (TB) with upper lobe cavitary disease frequently encountered in the male, called as TB type MAC disease. Here, we examined profiles of virulence and drug-susceptibiltiy of MAC strains isolated from Japanese patients with the NB type MAC disease (NB-MAC) and compared with the case of MAC isolates from Japanese patients with the TB type MAC disease (TB-MAC). Five each strains of NB-MAC and TB-MAC were compared with each other group for their invasiveness and the ability to intracellularly replicate in various types of cultured cells of human origin, including three macrophage cell lines and one alveolar and one bronchial epithelial cell lines. The following findings were obtained. (1) Within human macrophage cell lines, such as THP-1 and MM6 macrophages, NB-MAC strains replicated more rapidly when compared to TB-MAC strains, although such difference is insignificant. (2) There was observed no difference between NB-MAC and TB-MAC for the rate of intracellular growth within the U937 murine macrophage cell line. (3) Inside in the A549 human type II alveolar epithelial cell line, the intracellular growth of NB-MAC strains was somewhat more vigorous than TB-MAC strains. (4) Both NB-MAC and TB-MAC strains showed similar abilities to internalize into NL20 human bronchial epithelial cell line and intracellularly replicate within the NL20 cells. (5) In extracellular milieus such as those in 7HSF medium, NB-MAC grew more rapidly than TB-MAC. (6) Both NB- and TB-MAC strains induced reactive oxygen intermediate and reactive nitrogen intermediate production by THP-1 macrophages after bacterial internalization. These two types of MAC organisms showed the same efficacies in inducing macrophage generation of these antimicrobial effector molecules. (7) Drug susceptibilities of NB- and TB-MAC strains to some antimycobacterial drugs, such as rifampicin (RFP), fluoroquinolones and isoniazid (INH) were considerably different from each other, as follows. On the basis of MIC_<60>, NB-MAC was about four-times less susceptible to RFP, and fluoroquinolones (levofloxacin, gatifloxacin, sitafloxacin) than TB-MAC, while the former was two-times more susceptible to INH than the latter MAC strains. Both the two MAC showed the same levels of susceptibility to the other test drugs, including macrolides (clarithromycin, azithromycin), rifabutin, ethambutol and aminoglycosides (streptomycin, amikacin). The present findings indicate the following. First, there may be no essential difference in virulence on the basis of infectivity to host macrophages and lung epithelial cells between MAC strains isolated from NB-MAC disease and those from TB-MAC disease. Second, There may be some levels of difference in drug susceptibility for these two types of MAC isolates, especially in cases of RFP, fluoroquinolones and INH, thereby suggesting the possibility that clinical output of treatment of MAC patients using these drugs may differ from patients with NB type disease to those with TB type one. Less