Memories of pneumocystis pneumonia and thoughts of prophylaxis
Nov. 27, 2017
My childhood friend Alan was a rotating surgical resident at Methodist Hospital in Houston when he saw my brother Andrew in the ICU. “Warren, I think you better come here ASAP.” Thirty-six years ago, the first sight of my severely jaundiced brother, with nasal necrosis (presumably mucormycosis), and a chest X-ray that screamed Pneumocystis, was an emotional tour de force as I have never experienced before or since. Just a year past my internal medicine internship at Bellevue Hospital, I knew that Andrew’s death was imminent. Somehow he had always pulled through his innumerable febrile and surgical episodes from Crohn disease. Not this time. As I called my parents to tell them that their son would not survive, I felt paralyzed by the simultaneous explosion of tears, fright, and sense of impending loss.
Pneumocystis pneumonia (PCP) is an opportunistic infection caused by the fungus Pneumocystis jiroveci, formerly designated Pneumocystis carinii. Antimicrobial prophylaxis in human immunodeficiency virus (HIV) population has significantly decreased mortality and has been recommended in patients with CD4+ T lymphocyte counts below 200 cells/mm3. Prophylaxis is usually with trimethoprim–sulfamethoxazole; second-line therapies include dapsone, atovaquone, and pentamide. PCP may occur in patients receiving systemic immunosuppression for malignancies, organ transplantation, and autoimmune diseases, raising the issue prophylaxis for these individuals. (1)
A study describing recent trends in mortality and the estimated burden of PCP in the United States between was performed. In total, 11,512 PCP deaths occurred during 1999-2014. Annual age-adjusted PCP mortality decreased over this time period, from 0.479 to 0.154 per 100 000 population (1999 versus 2014 respectively). Over two-thirds of decedents were male and blacks had the highest mortality as compared to whites. HIV co-diagnosis accounted for 48% of all PCP deaths in 2014 versus 71% in 1999. Comorbid conditions such as connective tissue disorders (matched odds ration MOR=12.29) were associated with a PCP diagnosis. Although widespread use of antiretroviral therapy and PCP prophylaxis for HIV infection likely contributed to the overall decline in PCP deaths during 1999-2014, a continual need exists to prevent and treat this fungal disease in immunocompromised populations that are not infected with HIV. (1)
Although the criteria for PCP prophylaxis are well defined for HIV patients, guidelines for other immunosuppressed patients are not as clear. A risk for PCP infection greater than 3.5% has been proposed as a cut off for PCP prophylaxis in any particular disease which balances the number needed to treat against the number needed to harm. Wolfe and Peacock, in their review of PCP prophylaxis in the rheumatologic literature assert: “Upon reviewing guidelines published since 2015, prophylaxis for PCP is recommended only for patients with ANCA-positive vasculitis, specifically granulomatosis with polyangiitis (GPA), who are undergoing intense induction therapy. Evidence-based recommendations for the prophylaxis of PCP in patients with CTDs cannot be provided. There is expert consensus that PCP prophylaxis is warranted in patients with GPA undergoing induction therapy. Prophylaxis should perhaps also be considered for other CTD patients who are receiving similar intense immunosuppressive therapy especially if they are lymphopenic or have a low CD4 count.” (3)
Questioning whether immunosuppressed patients with dermatologic disease should receive PCP prophylaxis, Gonzalez Santiago et al searched the literature from Jan. 1, 1993, to Dec. 31, 2013. Guidelines for PCP prophylaxis from other medical fields were also analyzed. Of 17 dermatology patients reported to have contracted PCP, 8 (47.1%) died of the pneumonia. Risk factors included lack of prophylaxis, systemic corticosteroid therapy, lymphopenia, hypoalbuminemia, low serum CD4 counts, comorbid pulmonary or renal disease, malignancy, and prior organ transplantation. Based on their analysis, the authors proposed that prophylaxis be considered in dermatology patients in whom treatment with systemic corticosteroids at doses exceeding 20 mg/day or treatment with corticosteroid-sparing immunosuppressive agents is anticipated for at least 4 weeks, and in patients with additional risk factors for PCP. (4)
Amber et al performed a retrospective analysis of patients with autoimmune blistering disease (pemphigus vulgaris/foliaceus, bullous pemphigoid, epidermolysis bullosa acquisita, mucous membrane pemphigoid/cicatricial pemphigoid, or anti-p200 pemphigoid) to determine the incidence of PCP infections. A total of 801 patients with autoimmune blistering diseases were included in this study; their mean (SD) age was 66.5 (17.6) years, and a total of 465 (58%) were female. Only one patient developed PCP, resulting in an incidence rate of 0.1%. This incidence significantly fell below the recommended threshold of 3.5%. The authors concluded that routine Pneumocystis prophylaxis for patients with autoimmune blistering diseases does not seem to be warranted. (5)
Prophylaxis or no prophylaxis for PCP? — that is the question (for non-HIV immunosuppressed patients). PCP is rare, but potentially fatal. The only conclusion that can be reached is that while routine PCP prophylaxis may not be necessary for most dermatologic patients, there may be those at particular risk where prophylaxis could be life saving. Future studies will sort this out. In the interim, we should work in tandem with our infectious disease colleagues on a case-by-case basis if there is any uncertainty about the need for PCP prophylaxis.
1. Amber KT. Balancing the risks and benefits of prophylaxis: A reply to “Pneumocystis jiroveci pneumonia in patients treated with systemic immunosuppressive agents for dermatologic conditions. Int J Dermatol 2017; 56: e4-5.
2. Wickramasekaran RN, et al. The changing trends and profile of pneumocystis mortality in the United States, 1999-2014. Mycoses 2017; 60: 607-15.
3. Wolfe RM, Peacock JE Jr. Pneumocystis pneumonia and the rheumatologist: Which patients are at risk and how can PCP be prevented? Curr Rheumatol Rep 2017; 19: 35.
4. Gonzalez Santiago TM, et al. Pneumocystis jiroveci pneumonia in patients treated with systemic immunosuppressive agents for dermatologic conditions: A systematic review with recommendations for prophylaxis. Int J Dermatol 2016; 55: 823-30.
5. Amber KT, et al. Determining the incidence of pneumocystis pneumonia in patients with autoimmune blistering diseases not receiving routine prophylaxis. JAMA Dermatol 2017; 153: 1137-11.
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