Infectious Disease Division, Winthrop-University Hospital, Mineola, NY 11501, USA.
Heart Lung. 2012 May;41(3):310-5. doi: 10.1016/j.hrtlng.2011.05.009. Epub 2011 Oct 11.
Solid organ transplants (SOTs) may be complicated by a wide variety of infectious and noninfectious pulmonary disorders. Transplant patients receive immunosuppressive drugs to prevent rejection, but these drugs also predispose them to infection. Because immunosuppressive therapy impairs T-lymphocyte function, ie, cell-mediated immunity, such therapy, not surprisingly, predisposes patients to intracellular pulmonary pathogens. Community-acquired pneumonia (CAP) in patients with SOT usually involves one of the common typical or atypical bacterial CAP pathogens infecting immunocompetent hosts. The most frequent intracellular CAP pathogens in SOTs during immunosuppressive therapy are viral, eg, cytomegalovirus (CMV), respiratory syncytial virus (RSV), and herpes simplex virus (HSV). In addition, intracellular fungal pathogens are also common in patients with SOTs during immunosuppressive therapy, eg, Pneumocystis (carinii) jiroveci pneumonia (PCP). In addition, a variety of noninfectious disorders are not uncommon in patients with SOTs, including bronchiolitis obliterans organizing pneumonia (BOOP). Bronchiolitis obliterans organizing pneumonia may be associated with a variety of infectious agents, or may be attributable to drugs, including some immunosuppressive agents.
The clinical approach to CAP in patients with SOTs may be based on the appearance of the chest x-ray (CXR) or chest computed tomography scan, combined with the degree of hypoxemia (ie, the A-a gradient). Patients with SOTs and with a normal or nearly normal CXR and a high degree of hypoxemia (A-a gradient, >35) most often have an early viral pneumonia, eg, CMV or early PCP. If the CXR reveals bilateral patchy interstitial infiltrates and severe hypoxemia, the differential diagnosis is limited to moderate or severe viral pneumonia or PCP. Patients with SOTs and presenting with diffuse infiltrates and mild to moderate hypoxemia (A-a gradient, <35) are usually prone to noninfectious disorders, eg, congestive heart failure, pulmonary embolism, or drug-induced pneumonias. In patients with SOTs and CAP with focal or lobar infiltrates, the distribution of pathogens is the same as in immunocompetent hosts, ie, either a bacterial or atypical CAP pathogen.
A renal transplant patient developed bilateral patchy interstitial infiltrates with severe hypoxemia during hospitalization. The most likely differential diagnostic possibilities included PCP and BOOP. Bronchoalveolar lavage was performed to rule out PCP, and indicated cytopathic effects diagnostic of HSV pneumonia. Lung biopsy pathology confirmed the diagnosis of BOOP. In reviewing the patient's medications, we surmised that tacrolimus may have caused BOOP. The tacrolimus was discontinued, and the patient received acyclovir for HSV pneumonia.
实体器官移植（SOT）可能会出现多种感染性和非感染性肺部疾病。移植患者接受免疫抑制药物以预防排斥反应，但这些药物也使他们容易感染。由于免疫抑制疗法会损害 T 淋巴细胞功能，即细胞介导的免疫，因此这种疗法会使患者容易感染细胞内肺部病原体。SOT 患者的社区获得性肺炎（CAP）通常涉及感染免疫功能正常宿主的常见典型或非典型细菌性 CAP 病原体之一。SOT 患者在免疫抑制治疗期间最常见的细胞内 CAP 病原体是病毒，例如巨细胞病毒（CMV）、呼吸道合胞病毒（RSV）和单纯疱疹病毒（HSV）。此外，细胞内真菌病原体在 SOT 患者中也很常见，例如卡氏肺孢子虫肺炎（PCP）。此外，SOT 患者中还常见多种非传染性疾病，包括闭塞性细支气管炎伴机化性肺炎（BOOP）。BOOP 可能与多种感染因子有关，也可能归因于药物，包括一些免疫抑制剂。
SOT 患者 CAP 的临床方法可以基于胸部 X 射线（CXR）或胸部计算机断层扫描的外观，结合低氧血症的程度（即 A-a 梯度）。SOT 患者的 CXR 正常或几乎正常，且低氧血症程度较高（A-a 梯度，>35），通常会出现早期病毒性肺炎，例如 CMV 或早期 PCP。如果 CXR 显示双侧斑片状间质性浸润和严重低氧血症，鉴别诊断仅限于中度或重度病毒性肺炎或 PCP。SOT 患者出现弥漫性浸润和轻度至中度低氧血症（A-a 梯度，<35），通常易患非传染性疾病，例如充血性心力衰竭、肺栓塞或药物性肺炎。SOT 患者 CAP 出现局灶性或肺叶性浸润，病原体的分布与免疫功能正常宿主相同，即细菌性或非典型性 CAP 病原体。
一名肾移植患者在住院期间出现双侧斑片状间质性浸润和严重低氧血症。最可能的鉴别诊断可能性包括 PCP 和 BOOP。进行了支气管肺泡灌洗以排除 PCP，并显示出符合单纯疱疹病毒性肺炎的细胞病变效应。肺活检病理证实了 BOOP 的诊断。在回顾患者的药物治疗时，我们推测他克莫司可能导致了 BOOP。停用了他克莫司，患者接受阿昔洛韦治疗单纯疱疹病毒性肺炎。
