每日一题_2023.06.27

A 3-week-old girl is brought to the emergency department by her mother, who says her daughter has suddenly developed a large, tense bulge on the top of her head and a fever. The mother also notes that the patient has become more irritable and has not been feeding well. Although her mother received limited prenatal care, the child was born at 38 weeks’ gestation via spontaneous vaginal delivery without complications. The patient undergoes lumbar puncture, and a Gram stain of cerebrospinal fluid is shown in the image. Which of the following best characterizes the disease-causing agent in this patient?

一个三周大的女孩被她的母亲带到急诊室，她说她的女儿突然在她的头顶上出现了一个巨大的、紧张的隆起，并发烧。母亲还注意到患者变得更急躁，喂养不佳。尽管其母亲产前检查有限，但患儿于孕38周通过阴道自然分娩出生，无并发症。患者接受腰椎穿刺，脑脊液的革兰染色在图像中显示。下列哪项是该患者的致病因素的最佳特征?

(A)  Gram-negative bacilli, lactose fermenter 革兰氏阴性杆菌，乳糖发酵罐

(B)  Gram-negative coccobacilli, grows on chocolate agar with factors V and X 在巧克力琼脂上生长的革兰阴性球杆菌，具有V和X因子

(C)  Gram-positive bacilli, facultative intracellular 革兰阳性杆菌，兼性胞内

(D)  Gram-positive cocci, α-hemolytic, optochin-sensitive, bile-soluble 革兰氏阳性球菌，α溶血，光素敏感，胆溶性

(E)  Gram-positive cocci, b-hemolytic, bacitracin-resistant 革兰氏阳性球菌，β溶血，杆菌肽耐药

答案解析：

该患者的表现高度怀疑细菌性脑膜炎。与年龄较大的儿童或成人(颈项强直)相比，新生儿的临床症状(发热、易激惹、嗜睡、喂养不良)无特异性。新生儿脑膜炎的最常见原因是B族链球菌，特别是无乳链球菌，这是一种存在于链中的β -溶血性革兰阳性球菌。与A组相比，无乳链球菌对杆菌素具有抗性。这种细菌的感染发生在阴道分娩期间，因为40%的女性是胃肠道和阴道内这种细菌的无症状携带者。大肠埃希菌和单核细胞增生李斯特菌是3个月大婴儿脑膜炎的第二和第三大常见病因。

正确答案：E