Hypothetical pneumocystis jirovecii transmission from immunocompetent carriers to infant response

LETTERS Spelling Pneumocystis jirovecii To the Editor: Our 2002 article in Emerging Infectious Diseases about nomenclature changes for organisms in the genus Pneumocystis (1) has been widely cited and probably will remain a source for persons seeking information about this subject. Therefore, we need to correct an error in 1 of the species names presented in our article and in the 1999 article by Frenkel (2) on which our article was based. In the 1999 article, Frenkel proposed that the species of Pneumocystis found in humans be named to honor the Czech parasitologist, Otto Jirovec. The 1999 article was his second proposal for this change. In 1976, he fi rst named the human pathogen Pneumocystis jiroveci (3), at which time it was classifi ed as a protozoan and therefore named according to the International Code of Zoological Nomenclature. By 1999, it had become clear that the organisms in the genus Pneumocystis are fungi, which are named according to the International Code of Botanical Nomenclature (ICBN) (4). Differences between the International Code of Zoological Nomenclature and ICBN resulted in the realization of an error in the species epithet proposed by Frenkel in 1999, and our 2002 article contained this error. Frenkel’s 1999 article should have modifi ed the species epithet from “jiroveci” to “jirovecii,” (ICBN Articles 32.7 and 60.11 and Rec. 60C.1b). The correct and valid name under ICBN is Pneumocystis jirovecii. Redhead et al. further explain the basis for this correction (5). James R. Stringer, Charles B. Beard, and Robert F. Miller Author affi liations: University of Cincinnati, Cincinnati, Ohio, USA (J.R. Stringer); Centers for Disease Control and Prevention, Fort Collins, Colorado, USA (C.B. Beard); and University College, London, UK (R.F. Miller) DOI: 10.3201/eid1503.081060 References 1. Stringer JR, Beard CB, Miller RF, Wakefi eld AE. A new name (Pneumocystis jiroveci) for Pneumocystis from humans. Emerg Infect Dis. 2002;8:891–6. 2. Frenkel JK. Pneumocystis pneumonia, an immunodefi ciency-dependent disease (IDD): a critical historical overview. J Eukaryot Microbiol. 1999;46:89S–92S. 3. Frenkel JK. Pneumocystis jiroveci n. sp. from man: morphology, physiology, and immunology in relation to pathology. Natl Cancer Inst Monogr. 1976;43:13–30. 4. International Association for Plant Taxonomy. International Code of Botanical Nomenclature (Vienna Code). [cited 2009 Jan 30] Available from http://ibot.sav.sk/ icbn/main.htm 5. Redhead SA, Cushion MT, Frenkel JK, Stringer JR. Pneumocystis and Trypanosoma cruzi: nomenclature and typifi cations. J Eukaryot Microbiol. 2006;53:2–11. DOI: 10.1111/j.1550-7408.2005.00072.x Address for correspondence: James R. Stringer, Department of Molecular Genetics, Biochemistry, and Microbiology, College of Medicine, University of Cincinnati, ML 524 231 Albert Sabin Way, Cincinnati, OH 45267, USA; email: [email protected] Hypothetical Pneumocystis jirovecii Transmission from Immunocompetent Carriers to Infant To the Editor: The recent dispatch article by Rivero et al. reports the transmission of Pneumocystis jirovecii from immunocompetent grandparents to their granddaughter (1). The authors’ conclusion was based on 2 facts: the grandparents were carriers but neither the parents nor the child’s brother was a carrier, and the P. jirovecii genotype observed in the grandparents was identical to that found in the infant. In our opinion, the data provided by the authors do not support the conclusion that transmission has occurred. First, the 2 markers used for typing show a small number of alleles and thus provide low discrimination among isolates (2). Consequently, the P. jirovecii isolates present in the grandparents and in the infant may have been epidemiologically unrelated. Second, the frequency of occurrence of the different genotypes obtained was not investigated. The presence of the same genotype in the grandparents and in the infant may result from a high frequency of this genotype in the geographic area where the family lived. In fact, the use of a validated typing method and the analysis of unlinked control patients have proven necessary in other studies to demonstrate transmission of P. jirovecii (3–7). We believe that the reported transmission event remains a hypothesis. Philippe Hauser, Meja Rabodonirina, and Gilles Nevez Author affi liations: Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland (P. Hauser); Université Claude-Bernard, Hospices Civils 506 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 15, No. 3, March 2009 Letters Letters commenting on recent articles as well as letters reporting cases, outbreaks, or original research are welcome. Letters commenting on articles should contain no more than 300 words and 5 references; they are more likely to be published if submitted within 4 weeks of the original article’s publication. Letters reporting cases, outbreaks, or original research should contain no more than 800 words and 10 references. They may have 1 Figure or Table and should not be divided into sections. All letters should contain material not previously published and include a word count. LETTERS de Lyon, Lyon, France (M. Rabodonirina); and Université de Brest, Brest, France (G. Nevez) DOI: 10.3201/eid1503.081350 References 1. Rivero L, de la Horra C, Montes-Cano MA, Rodríguez-Herrera A, Respaldiza N, Friaza V, et al. Pneumocystis jirovecii transmission from immunocompetent carriers to infant. Emerg Infect Dis. 2008;14:1116–8. DOI: 10.3201/ eid1407.071431 2. Beard CB, Roux P, Nevez G, Hauser PM, Kovacs JA, Unnasch TR, et al. Strain typing methods and molecular epidemiology of Pneumocystis pneumonia. Emerg Infect Dis. 2004;10:1729–35. 3. de Boer MG, Bruijnesteijn van Coppenraet LE, Gaasbeek A, Berger SP, Gelinck LB, van Houwelingen HC, et al. An outbreak of Pneumocystis jiroveci pneumonia with 1 predominant genotype among renal transplant recipients: interhuman transmission or a common environmental source? Clin Infect Dis. 2007;44:1143–9. DOI: 10.1086/513198 4. Höcker B, Wendt C, Nahimana A, Tönshoff B, Hauser PM. Molecular evidence of Pneumocystis transmission in pediatric transplant unit. Emerg Infect Dis. 2005;11:330–2. 5. Rabodonirina M, Vanhems P, Couray- Targe S, Gillibert RP, Ganne C, Nizard N, et al. Molecular evidence of interhuman transmission of Pneumocystis pneumonia among renal transplant recipients hospitalized with HIV-infected patients. Emerg Infect Dis. 2004;10:1766–73. 6. Schmoldt S, Schuhegger R, Wendler T, Huber I, Söllner H, Hogardt M, et al. Molecular evidence of nosocomial Pneumocystis jirovecii transmission among 16 patients after kidney transplantation. J Clin Microbiol. 2008;46:966–71. DOI: 10.1128/JCM.02016-07 7. Nevez G, Chabé M, Rabodonirina M, Virmaux M, Dei-Cas E, Hauser PM, et al. Nosocomial Pneumocystis jirovecii infections. Parasite. 2008;15:359–65. Address for correspondence: Philippe Hauser, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Institute of Microbiology, Rue Bugnon 48 Lausanne 1011, Switzerland; email: [email protected] In Response: We appreciate the comments from Hauser et al. (1) regarding our article that reported a case of Pneumocystis jirovecii transmission from colonized grandparents to their infant granddaughter (2). We agree with the authors that the 2 markers used for typing, which are described in our article, present a small number of alleles and thus provide low discrimination between isolates. However, these typing methods have been validated and have proven useful for molecular epidemiologic applications in P. jirovecii colonization studies (3,4). Unfortunately, other typing methods that can identify a high number of alleles, such as the sequence analysis of the internal transcribed spacer no. 1 and 2 gene regions, could not be used in our study because a low amplifi cation rate has been observed for these regions when such methods are used to study colonized subjects (5). On the other hand, the multitarget singlestrand conformation polymorphism method has been used only in patients with Pneumocystis pneumonia, and its usefulness for epidemiologic studies in colonized subjects has not been proven (6). For our study, we think that genotyping analysis of the mtL- SU rRNA gene together with the dihydropteroate synthase (DHPS) gene provided suffi cient epidemiologic information because this strategy allows identifi cation of 24 different combinations of genotypes. However, no typing method is able to demonstrate interhuman P. jirovecii transmission conclusively because a common environmental source of infection cannot be ruled out in any case. Therefore, as we noted in our article, “We cannot exclude the possibility that the cases described were infected by the same environmental source,” and we only hypothesized that “the infant was infected by P. jirovecii through close contact with her grandparents.” However, we continue to think that the airborne transmission of P. jirovecii from the grandfather to the grandmother and the infant is the most probable explanation based on genotype data. Also, all persons in close contact with the infant were studied, and only her grandparents were colonized by P. jirovecii. Future research is needed to assess the importance of colonized subjects in the P. jirovecii transmission to susceptible hosts. Laura Rivero, Carmen de la Horra, Marco A. Montes-Cano, Nieves Respaldiza, Vicente Friaza, Rubén Morilla, Sonia Gutiérrez, José M. Varela, Francisco J. Medrano, and Enrique J. Calderón Author affi liation: Instituto de Biomedicina de Sevilla, Virgen del Rocío University Hospital, Seville, Spain DOI: 10.3201/eid1503.081672 References 1. Hauser P, Rabodonirina M, Nevez G. Hypothetical Pneumocystis jirovecii transmission from immunocompetent carriers to infant. Emerg Infect Dis. 2009;15:506–7. 2. Rivero L, de la Horra C, Montes-Cano MA, Rodríguez-Herrera A, Respaldiza N, Friaza V, et al. Pneumocystis jirovecii transmission from immunocompetent carriers to infant. Emerg Infect Dis. 2008;14:1116–8. DOI: 10.3201/ eid1407.071431 3. Montes-Cano MA, de la Horra C, Martín-Juan J, Varela JM, Torronteras R, Respaldiza N, et al. Pneumocystis jirovecii genotypes in Spanish population. Clin Infect Dis. 2004;39:123–8. DOI: 10.1086/421778 4. Vidal S, de la Horra C, Martín J, Montes- Cano MA, Rodríguez E, Respaldiza N, et al. Pneumocystis jirovecii colonization in patients with interstitial lung disease. Clin Microbiol Infect. 2006;12:231–5. DOI: 10.1111/j.1469-0691.2005.01337.x 5. Esteves F, Montes-Cano MA, de la Horra C, Costa MC, Calderon EJ, Antunes F, et al. Pneumocystis jirovecii multilocus genotyping profi les in patients from Portugal and Spain. Clin Microbiol Infect. 2008;14:356–62. DOI: 10.1111/j.1469- 0691.2007.01944.x 6. Beard CB, Roux P, Nevez G, Hauser PM, Kovacs JA, Unnasch TR, et al. Strain typing methods and molecular epidemiology of Pneumocystis pneumonia. Emerg Infect Dis. 2004;10:1729–35. Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 15, No. 3, March 2009 507 The opinions expressed by authors contributing to this journal do not necessarily refl ect the opinions of the Centers for Disease Control and Prevention or the institutions with which the authors are affi liated.