Increasing frequency of Pneumocystis jirovecii pneumonia in renal transplant recipients in the United Kingdom: clonal variability, clusters, and geographic location.

To the Editor—Pneumocystis jirovecii is a well-described opportunistic pathogen in human immunodeficiency virus (HIV) infection, but it is less commonly associated with pneumonia in other states of immunocompromise. However, outbreaks of P. jirovecii pneumonia (PCP) have been described in renal transplant recipients in both Europe and Asia [1–3]. Explanations for this, including the possible modes of transmission, have not been established, and risk factors for the development of PCP remain poorly understood. However, policies relating to immunosuppression and HLA matching have changed in recent years [4], and PCP prophylaxis guidance in renal transplant recipients has a poor evidence base [5]. We write to draw attention to the preliminary results of investigation of 2 concurrent outbreaks of PCP in renal transplant recipients in the Northwest of England, followed by a United Kingdom–wide surveillance questionnaire of renal units with responses suggesting that there has been a national upsurge in such cases. Between November 2008 and July 2010, 21 cases of PCP were diagnosed in renal transplant recipients attending the transplant unit at the Royal Liverpool University Hospital, compared with 1 case in the