Original article/Article original
Characteristics of Pneumocystis pneumonia in Nancy from January 2007 to April 2011 and focus on an outbreak in nephrologyCaractéristiques des pneumocystoses à Nancy entre janvier 2007 et avril 2011 et focus sur une épidémie en néphrologie

https://doi.org/10.1016/j.mycmed.2013.10.003Get rights and content

Summary

Background

Pneumocystis jirovecii is responsible for pneumonia in immunocompromised populations. Pneumocystis pneumonia has first been discovered as a common and life-threatening opportunistic infection in HIV-infected patients.

Objectives

The aim of this study is to characterize the epidemiological aspects of Pneumocystis pneumonia and then to highlight an outbreak of this infection in a nephrology unit with molecular tools.

Patients/Methods

A multilocus sequence typing method has been used to study the epidemiology of strains isolated during this episode.

Results

From January 2007 to April 2011, 39 cases of P. jirovecii pneumonia have been observed. In two thirds of cases, underlying diseases as transplantations, hematologic or solid malignancies, or immunodepressed treatment were the main risk factors and in one third of cases, there were HIV positive patients. This distribution is due to an outbreak of 13 cases in a nephrology unit, where the MLST resulted in two strains profiles regrouping each one 6 and 4 cases among the 10 available isolates.

Conclusions

New categories of risk patients of Pneumocystis infection have emerged with severe clinical manifestations and mostly with a fatal outcome. The origin of the transmission is still unknown but a local transmission has been showed in our nephrology unit.

Résumé

Contexte

Pneumocystis jirovecii est responsable de pneumopathies chez les patients immunodéprimés. La pneumocystose était considérée initialement comme une infection opportuniste, commune et potentiellement mortelle des patients infectés par le VIH.

Objectifs

Les objectifs de cette étude sont de caractériser sur le plan épidémiologique des pneumocystoses et de mettre en évidence une épidémie dans un service de néphrologie par des outils moléculaires.

Patients/Méthodes

Une technique de MLST a étudié les caractéristiques moléculaires des souches de P. jirovecii isolées en néphrologie.

Résultats

De janvier 2007 à avril 2011, 39 cas de pneumocystose ont été observés. Dans deux tiers des cas, les principaux facteurs de risque sont les traitements immunosuppresseurs et les pathologies sous-jacentes telles que les transplantations, les hémopathies malignes ou les tumeurs solides. Dans un tiers des cas, les patients étaient infectés par le VIH. Cette répartition est due à une épidémie de 13 cas survenue dans le service de néphrologie. Le typage moléculaire a déterminé deux types de profils parmi les 10 isolats disponibles, regroupant chacun 6 et 4 cas.

Conclusions

De nouvelles catégories de patients à risque de pneumocystose ont émergé et les manifestations cliniques y sont sévères et généralement associées à un mauvais pronostic. L’origine de cette infection est encore inconnue mais une transmission locale a été observée dans un service de néphrologie.

Introduction

Pneumocystis jirovecii is an ascomycetous fungus responsible for pneumonia in immunocompromised populations. Pneumocystis pneumonia has mainly been described in HIV-infected patients as an opportunistic infection with a frequently fatal outcome. Recently, emergence of the disease has been reported in other immunodeficient patients including those affected by hematologic and solid malignancies, autoimmune or inflammatory diseases, or receiving bone marrow, stem cell or solid organ transplantations [4]. Although still limited by the lack of a culture method, advances have been made in the understanding of the biology, epidemiology, and pathogenesis of P. jirovecii with help of molecular methods. Despite these improvements, the exact transmission mode of the pathogen remains unclear. Currently, studies conducted on animals and humans are in favor of an airborne transmission for Pneumocystis pneumonia [4]. Moreover, recent data raised the hypothesis of an interhuman transmission by outlining several outbreaks of Pneumocystis pneumonia with, sometimes, the demonstration of nosocomial acquisition. Outbreak investigations of P. jirovecii are made with molecular typing tools [2]. A multilocus sequence typing method has been described by Hauser [8] and then used in different clinical investigations [7], [9], [15]. Nevertheless, the mechanism explaining the person-to-person spread or the environmental contamination from a common source is still unknown [4].

The aim of this study was to present a case series of 39 patients with Pneumocystis pneumonia, that were admitted between January 2007 and April 2011 at Nancy hospital. The epidemiology, clinical presentation, diagnostic method and evolution have been detailed. Secondarily, we have conducted a molecular investigation by using a multilocus sequence typing method on 10 strains isolated in the nephrology unit.

Section snippets

Patients specimens

Recruitment of patients with Pneumocystis pneumonia was performed at the Parasitology and Mycology Laboratory in Nancy hospital, France. In this study, the definition of Pneumocystis pneumonia focused on laboratory findings such as detection of cysts and/or trophic forms of P. jirovecii, associated to a strong clinical suspicion.

Two separate analyses have been conducted. First, an incidence study has been performed on the period from 1994 to 2010 by considering all the Pneumocystis pneumonia

Epidemiological aspects of Pneumocystis pneumonia

Two hundred and thirty-five cases of Pneumocystis pneumonia were included in the incidence study conducted on the period from 1994 to 2010. The evolution of the annual incidence of this infection is shown in Fig. 1. Before 1997, the number of cases was higher than after this period, with a maximum of 43 cases in 1996. After 10 years of regular fluctuation, a constant increase of incidence has been observed since 2006.

In Fig. 2, the number of Pneumocystis pneumonia cases has been analyzed

Discussion

In Nancy, the annual incidence of Pneumocystis pneumonia has strongly decreased since 1997 with a reduction of 67% between 1996 and 1997. The HAART development may explain this evolution for patients infected by HIV [10], [13], [17]. Afterwards, the incidence remained stable with approximately 9 cases per year until recently when an increase of Pneumocystis pneumonia has been observed whereas diagnosis methods have not changed. This increase has been explained by new risk factors for

Disclosure of interest

The authors declare that they have no conflicts of interest concerning this article.

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    Both authors A.D. and S.A. have contributed equally to this manuscript.

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