Characterization of a Novel Diarrheagenic Strain of Proteus mirabilis Associated With Food Poisoning in China
Characterization of a Novel Diarrheagenic Strain of Proteus mirabilis Associated With Food Poisoning in China
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中国与食物中毒相关的一种新的奇异变形杆菌腹泻菌株的特征
DOI：
10.3389/fmicb.2019.02810
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发表时间：
2019-12-12
影响因子：
5.2
通讯作者：
Cao, Hong
中科院分区：
文献类型：
--
作者：
Gong, Zelong;Shi, Xiaolu;Cao, Hong
奇异变形杆菌通常被认为是引起人类尿路感染（UTI）的机会性病原体。然而，一些奇异果菌株被发现与食物中毒事件有关，其致病机制仍不清楚。在我们的研究中，我们描述了从中国食物中毒患者的标本中分离出的一种新的奇异果菌株 C02011。为了确定其胃肠道致病性，我们进行了体外[Caco-2细胞：细菌粘附和侵袭测定、吉姆萨染色和透射电子显微镜（TEM）]和体内[BALB/c小鼠模型： 粪便特征、结肠损伤、组织学检查、免疫化学和蛋白质印迹（WB）]。结果显示，C02011菌株在细菌外观和增殖方面表现出与B02005菌株几乎相同的特征。在体外，Caco-2 细胞被奇异果 P. mirabilis C02011、B02005 和 P. mirabilis ATCC 29906 菌株感染。之后采用吉姆萨染色和TEM观察C02011菌株的感染过程。同时，不同菌株的粘附能力依次为：奇异果B02005>奇异果C02011>奇异果ATCC 29906（P < 0.01）。不同菌株的侵袭能力评定为：奇异果C02011>奇异果B02005>奇异果ATCC 29906（P < 0.01）。在体内，BALB/c 小鼠感染奇异假单胞菌 C02011 和 B02005 菌株。 C02011菌株在以下指标上表现出比B02005菌株更强的毒力：（1）粪便含水量和粪便性状； (2)小鼠结肠长度； (3)小鼠肠道组织的组织学检查； (4) ELISA检测结肠中TNF-α水平； (5)WB和免疫组织化学(IHC)用于检测结肠中occludin蛋白的表达。基于这些结果，我们首先验证了奇异变形杆菌C02011新菌株比从健康个体中分离的其他菌株表现出更强的胃肠道致病性。此外，初步证实IV型分泌系统（T4SS）在食物中毒事件中分离出的腹泻性奇异变形杆菌的发病机制中发挥重要作用。
Proteus mirabilis is commonly considered to be an opportunistic pathogen causing urinary tract infections (UTIs) in humans. However, some strains of P. mirabilis were found to be associated with food poisoning outbreaks, with the pathogenic mechanism still unclear. In our study, we described a novel strain of P. mirabilis C02011 isolated from patients’ specimens in a food poisoning in China. In order to determine its gastrointestinal pathogenicity, experiments were performed to compare P. mirabilis B02005 strain (isolated from healthy people) and P. mirabilis American Type Culture Collection (ATCC) 29906 strain both in vitro [Caco-2 cells: bacterial adhesion and invasion assays, Giemsa staining, and transmission electron microscopy (TEM)] and in vivo [BALB/c mouse model: fecal character, colon injury, histological examination, immunochemistry, and western blotting (WB)]. According to the results, C02011 strain exhibited almost identical characteristics with B02005 strain in bacterial appearance and proliferation. In vitro, Caco-2 cells were infected with P. mirabilis C02011, B02005, and P. mirabilis ATCC 29906 strains. After that, Giemsa staining and TEM were used for observing the infection process of C02011 strain. Meanwhile, the adhesive abilities of different strains were rated as follows: P. mirabilis B02005 > P. mirabilis C02011 > P. mirabilis ATCC 29906 (P < 0.01). Invasive abilities of different strains were rated as follows: P. mirabilis C02011 > P. mirabilis B02005 > P. mirabilis ATCC 29906 (P < 0.01). In vivo, BALB/c mice were infected with P. mirabilis C02011 and B02005 strains. C02011 strain shows more virulence than B02005 strain in terms of the following indicators: (1) feces water content and fecal character; (2) colon length of mice; (3) histological examination on mouse intestine tissues; (4) ELISA for detecting TNF-α level in the colon; and (5) WB and immunohistochemistry (IHC) for detecting occludin protein expression in the colon. On the basis of these results, we firstly validated that the novel strain of P. mirabilis C02011 shows more gastrointestinal pathogenicity than the other strains isolated from a healthy individual. In addition, type IV secretion system (T4SS) was preliminarily confirmed to play an important role in the pathogenesis of diarrheal P. mirabilis isolated from the food poisoning incident.