title: An outbreak of Pneumocystis jiroveci pneumonia with 1 predominant genotype among renal transplant recipients: interhuman transmission or a common environmental source?
abstract: BACKGROUND
  An outbreak of Pneumocystis jiroveci pneumonia (PCP) occurred among renal transplant recipients attending the outpatient department at the Leiden University Medical Centre (Leiden, The Netherlands) from 1 March 2005 through 1 February 2006. Clinical, epidemiological, and molecular data were analyzed to trace the outbreak's origin.
  
  
  METHODS
  Renal transplant recipients with a clinical suspected diagnosis of PCP were included in the study. The diagnosis had to be confirmed by direct microscopy or real-time polymerase chain reaction of the dihydropteroate synthase gene in a bronchoalveolar fluid specimen. To detect contacts between patients, a transmission map was constructed. A case-control analysis was performed to asses whether infection was associated with certain wardrooms. Genotyping of Pneumocystis isolates was performed by sequence analysis of the internal transcribed spacer (ITS) number 1 and 2 gene regions.
  
  
  RESULTS
  Twenty-two confirmed PCP cases were identified; approximately 0-1 would have been expected over the same time period. No risk factor was predominantly present, and standard immunosuppressive regimens had not changed. Liver transplant recipients who used the same outpatient facilities had not acquired PCP. The transmission map findings were compatible with interhuman transmission on multiple occasions. The case-control study did not point to wardrooms as a common source. Genotyping by sequencing of the ITS1 and ITS2 gene regions revealed type Ne in 12 of 16 successfully typed samples. Genotype Ne was found in only 2 of 12 reference samples.
  
  
  CONCLUSIONS
  The clinical data and genotyping results are compatible with either interhuman transmission or an environmental source of infection. More complex models may account for PCP clusters.
authors.affiliation: Department of Infectious Diseases, Centre for Infectious Diseases, Leiden University Medical Centre, Leiden, The Netherlands. M.G.J.de_Boer@lumc.nl
authors.forename: Mark G J
authors.initials: MG
authors.lastname: de Boer
authors.forename: Lesla E S
authors.initials: LE
authors.lastname: Bruijnesteijn van Coppenraet
authors.forename: Andre
authors.initials: A
authors.lastname: Gaasbeek
authors.forename: Stefan P
authors.initials: SP
authors.lastname: Berger
authors.forename: Luc B S
authors.initials: LB
authors.lastname: Gelinck
authors.forename: Hans C
authors.initials: HC
authors.lastname: van Houwelingen
authors.forename: Peterhans
authors.initials: P
authors.lastname: van den Broek
authors.forename: Ed J
authors.initials: EJ
authors.lastname: Kuijper
authors.forename: Frank P
authors.initials: FP
authors.lastname: Kroon
authors.forename: Jan P
authors.initials: JP
authors.lastname: Vandenbroucke
mesh_terms: D000369:Aged, 80 and over; D016902:Air Pollution, Indoor / Q000009:adverse effects; D016022:Case-Control Studies; D003428:Cross Infection / Q000635:transmission*; D004196:Disease Outbreaks; D005260:Female; D005838:Genotype; D006801:Humans; D016030:Kidney Transplantation; D008297:Male; D045363:Pneumocystis carinii / Q000235:genetics*; D011020:Pneumonia, Pneumocystis / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology