棘阿米巴属、福氏耐格里阿米巴和蠕虫阿米巴（哈特曼阿米巴）作为军团菌属载体在未处理和经太阳能巴氏杀菌的收集雨水中的分子检测
Molecular detection of Acanthamoeba spp., Naegleria fowleri and Vermamoeba (Hartmannella) vermiformis as vectors for Legionella spp. in untreated and solar pasteurized harvested rainwater.
作者信息
Dobrowsky Penelope H, Khan Sehaam, Cloete Thomas E, Khan Wesaal
机构信息
Department of Microbiology, Faculty of Science, Stellenbosch University, Private Bag X1, Stellenbosch, 7602, South Africa.
Faculty of Health and Applied Sciences, Namibia University of Science and Technology, 13 Storch Street, Private Bag 13388, Windhoek, Namibia.
出版信息
Parasit Vectors. 2016 Oct 10;9(1):539. doi: 10.1186/s13071-016-1829-2.
BACKGROUND
Legionella spp. employ multiple strategies to adapt to stressful environments including the proliferation in protective biofilms and the ability to form associations with free-living amoeba (FLA). The aim of the current study was to identify Legionella spp., Acanthamoeba spp., Vermamoeba (Hartmannella) vermiformis and Naegleria fowleri that persist in a harvested rainwater and solar pasteurization treatment system.
METHODS
Pasteurized (45 °C, 65 °C, 68 °C, 74 °C, 84 °C and 93 °C) and unpasteurized tank water samples were screened for Legionella spp. and the heterotrophic plate count was enumerated. Additionally, ethidium monoazide quantitative polymerase chain reaction (EMA-qPCR) was utilized for the quantification of viable Legionella spp., Acanthamoeba spp., V. vermiformis and N. fowleri in pasteurized (68 °C, 74 °C, 84 °C and 93 °C) and unpasteurized tank water samples, respectively.
RESULTS
Of the 82 Legionella spp. isolated from unpasteurized tank water samples, Legionella longbeachae (35 %) was the most frequently isolated, followed by Legionella norrlandica (27 %) and Legionella rowbothamii (4 %). Additionally, a positive correlation was recorded between the heterotrophic plate count vs. the number of Legionella spp. detected (ρ = 0.710, P = 0.048) and the heterotrophic plate count vs. the number of Legionella spp. isolated (ρ = 0.779, P = 0.0028) from the tank water samples collected. Solar pasteurization was effective in reducing the gene copies of viable V. vermiformis (3-log) and N. fowleri (5-log) to below the lower limit of detection at temperatures of 68-93 °C and 74-93 °C, respectively. Conversely, while the gene copies of viable Legionella and Acanthamoeba were significantly reduced by 2-logs (P = 0.0024) and 1-log (P = 0.0015) overall, respectively, both organisms were still detected after pasteurization at 93 °C.
CONCLUSIONS
Results from this study indicate that Acanthamoeba spp. primarily acts as the vector and aids in the survival of Legionella spp. in the solar pasteurized rainwater as both organisms were detected and were viable at high temperatures (68-93 °C).
背景
军团菌属采用多种策略来适应压力环境，包括在保护性生物膜中增殖以及与自由生活变形虫（FLA）形成共生关系的能力。本研究的目的是鉴定在收集的雨水和太阳能巴氏杀菌处理系统中持续存在的军团菌属、棘阿米巴属、蠕虫阿米巴（哈特曼氏阿米巴）和福氏耐格里阿米巴。
方法
对经过巴氏杀菌（45℃、65℃、68℃、74℃、84℃和93℃）和未经过巴氏杀菌的水箱水样进行军团菌属筛查，并计数异养平板菌落数。此外，分别利用单叠氮溴化乙锭定量聚合酶链反应（EMA-qPCR）对经过巴氏杀菌（68℃、74℃、84℃和93℃）和未经过巴氏杀菌的水箱水样中的活军团菌属、棘阿米巴属、蠕虫阿米巴和福氏耐格里阿米巴进行定量。
结果
从未经过巴氏杀菌的水箱水样中分离出的82株军团菌属中，长滩军团菌（35%）是最常分离到的，其次是诺尔兰军团菌（27%）和罗博特姆军团菌（4%）。此外，在收集的水箱水样中，异养平板菌落数与检测到的军团菌属数量之间呈正相关（ρ = 0.710，P = 0.0。其次是诺尔兰军团菌（27%）和罗博特姆军团菌（4%）。此外，在收集的水箱水样中，异养平板菌落数与检测到的军团菌属数量之间呈正相关（ρ = 0.710，P = 0.048），异养平板菌落数与分离出的军团菌属数量之间也呈正相关（ρ = 0.779，P = 0.0028）。太阳能巴氏杀菌在68 - 93℃和74 - 93℃的温度下分别有效地将活蠕虫阿米巴（3个对数级）和福氏耐格里阿米巴（5个对数级）的基因拷贝数降低到检测下限以下。相反，虽然活军团菌和棘阿米巴的基因拷贝数总体上分别显著降低了2个对数级（P = 0.0024）和1个对数级（P = 0.0015），但在93℃巴氏杀菌后仍能检测到这两种生物。
结论
本研究结果表明，棘阿米巴属主要作为载体，并有助于军团菌属在太阳能巴氏杀菌雨水中存活，因为在高温（68 - 93℃）下这两种生物均被检测到且具有活力。
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