肺鼻疽奴卡菌病并发多发脑脓肿的病原学鉴定与临床分析

Pathogen identification and clinical analysis of Nocardia farcinica isolated from a patient suffered from pulmonary nocardiosis complicated with brain abscess

目的探讨肺鼻疽奴卡菌病合并多发脑脓肿的病原学特点,为临床诊疗该类疾病提供依据。方法分析患者的临床资料、影像学检查、诊疗经过和实验室对病原菌的分离鉴定、药敏试验和16S r RNA序列测定并复习相关文献。结果该患者有长期服用糖皮质激素史,临床表现为发热、咳嗽等,实验室检测白细胞、中性粒细胞、C-反应蛋白升高;痰培养2 d后有细菌生长,菌落白色粗糙、有皱褶,革兰染色镜检为串珠状或分枝状革兰阳性杆菌,1%硫酸弱抗酸染色及抗酸染色均阴性;分离菌经细菌自动化鉴定仪鉴定未出结果,质谱和16S r RNA测序鉴定为鼻疽奴卡菌。药敏结果显示阿米卡星、环丙沙星、亚胺培南、左氧氟沙星、利奈唑胺和米诺环素敏感,复方新诺明、头孢曲松、氨苄西林和红霉素耐药。肺部影像学显示,双肺多发斑片状阴影、结节,后发展为空洞,脑CT示多发脑脓肿。应用复方磺胺甲噁唑和头孢曲松联合治疗后肺部空洞吸收好转,经外科手术引流及脓肿切除后患者病情稳定,回当地治疗。结论分子学方法鉴定鼻疽奴卡菌快速、准确,早期病原诊断是治疗奴卡菌病的关键,治疗应以磺胺类为主的联合治疗、早期、足量、足疗程。

Objective To identity the pathogen of pulmonary nocardiosis complicated with brain abscess and to provide assistance for clinical diagnosis and therapy. Methods The clinical data, imaging examination, diagnosis and treatment were reviewed, respectively, and the identification of pathogenic bacteria, antimicrobial susceptibility testing and 16 S r RNA sequence were determined. Results The patient had a history of long-term administration of corticosteroids. Clinical manifestations were fever and cough. The results of laboratory showed that white blood cell, neutrophil cells and C-reactive protein(CRP) were all above normal range. The colonies were white, rough and surface folds after 2 days culture of sputum. Gram staining for the sputum samples and the isolate were beaded or branched Gram-positive bacilli.The weak acid fast staining test by 1% sulfuric acid and acid fast staining test were both negative. The isolate could not be identified by automatic bacteria identification instrument. Nocardia farcinica was identified by Matrix-Assisted Laser Desorption Ionization-time of Flight Mass Spectrometry(MODI-TOF MS) and 16 S r RNA sequencing. Antimicrobial susceptibility detection by KB disks method showed that it were sensitive to amikacin, ciprofloxacin, imipenem, levofloxacin, linezolid and minocycline, but resistant to cotrimoxazole, ceftriaxone, ampicillin and erythromycin. Lung imaging showed that the double lung multiple patchy shadows, nodules, and later developed into the cavity. Brain CT showed multiple brain abscess. After application of sulfamethoxazole ceftriaxone combined with, the pulmonary cavity was absorbed and the patient’s condition were stable after surgical drainage and excision of abscess. Conclusions Molecular method for identification of Nocardia farcinica is rapid, accurate. Early pathogenic diagnosis was the key for treatment of nocardiosis. Combination treatment including sulfonamides, early, sufficient, full course of treatment should be executive.