Rajkarnikar Ruja, Sharma Shriya, Yadav Sumit, Ghimire Nirmal
Kathmandu Medical College.
Nepalese Army Institute of Health Sciences.
Ann Med Surg (Lond). 2023 Feb 17;85(3):523-527. doi: 10.1097/MS9.0000000000000249. eCollection 2023 Mar.
Infective endocarditis is an infection of the heart valves or endocardium caused by bacterial, viral, or fungal microorganisms. Blood cultures are used to detect the bacteria causing infective endocarditis, and echocardiography is performed to find the damaged heart valves. In blood culture-negative endocarditis, no endocarditis-causing organisms can be found in blood cultures, and blood cultures using usual laboratory methods remain sterile after inoculation of at least three independent blood samples.
A 24-year-old male with a history of polysubstance abuse presented with complaints of fever, cough, and shortness of breath. He had a past history of pulmonary tuberculosis 4 years ago, for which he was treated with antitubercular therapy. High-resolution computed tomography of the chest revealed multiple cavitary lesions and consolidative areas in the bilateral lungs. Based on these findings, a provisional diagnosis of reactivation of pulmonary tuberculosis was considered, and antitubercular therapy was started. Due to his deteriorating condition, he was readmitted and evaluated. Bronchoalveolar lavage was done and sent for culture and sensitivity testing, which showed the presence of , and treatment was started accordingly. Despite continuing intravenous antibiotics for 5 days, the patient was not improving. Three sets of samples were withdrawn for blood culture and sensitivity testing, which came out to be negative. Transthoracic echocardiography was done, which revealed vegetation in the tricuspid valve. The patient was diagnosed with culture-negative tricuspid valve endocarditis based on the clinical criteria.
Blood culture-negative endocarditis is difficult to diagnose and presents challenges. When faced with a diagnosis like culture-negative endocarditis in the context of a condition that can appear very similar, like tuberculosis, a broad differential diagnostic approach is important.
Intravenous drug use is the main cause of right-sided valvular infective endocarditis. Endocarditis should be considered in intravenous drug users even in the absence of positive blood cultures. An appropriate antibiotic regimen and long-term follow-up with a multidisciplinary team are necessary for a good outcome.
感染性心内膜炎是由细菌、病毒或真菌微生物引起的心脏瓣膜或心内膜感染。血培养用于检测引起感染性心内膜炎的细菌，超声心动图用于发现受损的心脏瓣膜。在血培养阴性的心内膜炎中，血培养中找不到引起心内膜炎的病原体，使用常规实验室方法进行的血培养在接种至少三个独立血样后仍保持无菌状态。
一名有多种物质滥用史的24岁男性，出现发热、咳嗽和呼吸急促的症状。他4年前有肺结核病史，曾接受抗结核治疗。胸部高分辨率计算机断层扫描显示双侧肺部有多个空洞性病变和实变区域。基于这些发现，考虑初步诊断为肺结核复发，并开始抗结核治疗。由于病情恶化，他再次入院并接受评估。进行了支气管肺泡灌洗并送去进行培养和药敏试验，结果显示存在[此处原文缺失相关内容]，并据此开始治疗。尽管持续静脉注射抗生素5天，患者病情仍未改善。采集了三组样本进行血培养和药敏试验，结果均为阴性。进行了经胸超声心动图检查，显示三尖瓣有赘生物。根据临床标准，该患者被诊断为血培养阴性的三尖瓣心内膜炎。
血培养阴性的心内膜炎难以诊断且存在挑战。当在类似肺结核这种可能表现非常相似的疾病背景下面对血培养阴性的心内膜炎这样的诊断时，广泛的鉴别诊断方法很重要。
静脉吸毒是右侧瓣膜感染性心内膜炎的主要原因。即使血培养未呈阳性，静脉吸毒者也应考虑患有心内膜炎。为取得良好预后，需要适当的抗生素治疗方案以及多学科团队的长期随访。
