A Pneumocystis jirovecii pneumonia outbreak in a single kidney-transplant center: role of cytomegalovirus co-infection

Pneumocystis jirovecii pneumonia (PCP) and cytomegalovirus (CMV) infection represent possible complications of medical immunosuppression. Between 2005 and 2010, non-human immunodeficiency virus (HIV) PCP patients admitted to a nephrology unit were analyzed for outcome, CMV comorbidity, and patient-to-patient contacts prior to PCP. In contrast to 2002-2004 (no cases) and 2008-2010 (10 cases), a PCP outbreak of 29 kidney-transplant recipients and one patient with anti-glomerular basement membrane disease occurred between 2005 and 2007. None of the patients were on PCP chemoprophylaxis. In four PCP patients, the genotyping data of bronchoalveolar lavage specimen showed an identical Pneumocystis strain. PCP cases had a higher incidence of CMV infection (12 of 30 PCP patients) and CMV disease (four patients) when compared to matched PCP-free controls (p < 0.05). Cotrimoxazole and, if applicable, ganciclovir were started 2.0 +/- 4.0 days following admission, and immunosuppressive medication was reduced. In-hospital mortality was 10% and the three-year mortality was 20%. CMV co-infection did not affect mortality. CMV co-infection more frequently occurred during a cluster outbreak of non-HIV PCP in comparison to PCP-free controls. Here, CMV awareness and specific therapy of both CMV infection and PCP led to a comparatively favorable patient outcome. The role of patient isolation should be further investigated in incident non-HIV PCP.