Background The overall incidence of Pneumocystis jirovecii pneumonia (PJP) in solid organ transplant recipients is 5–15%. A timely diagnosis of PJP is difficult and relies on imaging and detection of the organism. Methods We present a case series of four patients displaying hypercalcaemia with an eventual diagnosis of PJP and document the management of the outbreak with a multidisciplinary team approach. We discuss the underlying pathophysiology and previous reports of hypercalcaemia preceding a diagnosis of PJP. We also reviewed the evidence concerning PJP diagnosis and treatment. Results Within our renal transplant cohort, four patients presented within 7?months with hypercalcaemia followed by an eventual diagnosis of PJP. We measured their corrected calcium, parathyroid hormone (PTH), 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] and 25-hydroxycholecalciferol [25(OH)D] levels at admission and following treatment of PJP. All four patients diagnosed with PJP were 4–20?years post-transplantation. Three of the four patients demonstrated PTH-independent hypercalcaemia (corrected calcium >3.0?mmol/L). The presence of high 1,25(OH)2D3 and low 25(OH)D levels suggest negation of the negative feedback mechanism possibly due to an extrarenal source; in this case, the alveolar macrophages. All four patients had resolution of their hypercalcaemia after treatment of PJP. Conclusions Given the outbreak of PJP in our renal transplant cohort, and based on previous experience from other units nationally, we implemented cohort-wide prophylaxis with trimethoprim–sulphamethoxazole for 12?months in consultation with our local infectious diseases unit. Within this period there have been no further local cases of PJP.
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机译：背景实体器官移植受者中吉氏肺孢子虫肺炎（PJP）的总发生率为5-15％。对PJP的及时诊断非常困难，并且依赖于生物体的成像和检测。方法我们介绍了四例表现为高钙血症并最终诊断为PJP的病例，并采用多学科团队方法记录了暴发的处理。我们讨论了诊断PJP之前的潜在病理生理学和高钙血症的先前报道。我们还审查了有关PJP诊断和治疗的证据。结果在我们的肾脏移植队列中，有4名患者在7个月内出现高钙血症，随后最终诊断为PJP。我们测量了他们校正后的钙，甲状旁腺激素（PTH），1,25-二羟基胆钙化固醇[1,25-（OH） 2 D 3 ]和25-羟基胆钙化固醇[25（ PJP入院时和治疗后的OH）D]水平。所有四名被诊断为PJP的患者均在移植后4至20年。四名患者中的三名表现出不依赖PTH的高钙血症（校正钙> 3.0？mmol / L）。 1,25（OH） 2 D 3 的高水平和25（OH）D的低水平的存在提示负反馈机制的否定可能是由于肾外来源引起的。在这种情况下，是肺泡巨噬细胞。所有四名患者在接受PJP治疗后均解决了高钙血症。结论鉴于我们的肾脏移植队列中爆发了PJP，并根据全国其他部门的先前经验，我们与甲氧苄氨嘧啶-磺胺甲恶唑联合进行了全队列的预防，并咨询了当地的传染病部门，为期12个月。在此期间，当地没有再发生PJP病例。
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