Enrique Calderón

Pneumocystis jirovecii in General Population

P. jirovecii colonization can be frequently detected in immunocompetent adults, which suggests that the general population could be a source of this infection.

Pneumocystis infection in humans: diagnosis and treatment

Pneumocystis jirovecii is an atypical fungus exhibiting pulmonary tropism and a highly defined host specificity. It is generally regarded as an opportunistic microorganism causing serious pneumonia in AIDS patients. However, with the currently rising number of patients receiving immunosuppressive therapies for malignancies, allogeneic organ transplantations and autoimmune diseases, Pneumocystis pneumonia is becoming more and more recognized in non-HIV immunosuppressed individuals. The clinical presentation in HIV-infected patients may differ from that in other immunocompromised patients and its diagnosis continues to be challenging as there are no specific symptoms or signs. Cotrimoxazole is the drug of choice for prophylaxis and therapy of any form or severity of Pneumocystis pneumonia, but there are only a few options for other alternative treatments. The management of this pneumonia remains a major challenge for all physicians caring for immunosuppressed patients.

Pneumocystis jirovecii transmission from immunocompetent carriers to infant.

We report a case of Pneumocystis jirovecii transmission from colonized grandparents to their infant granddaughter. Genotyping of P. jirovecii showed the same genotypes in samples from the infant and her grandparents. These findings support P. jirovecii transmission from immunocompetent carrier adults to a susceptible child.

Pneumocystis carinii pneumonia in heart transplant recipients

OBJECTIVES In spite of the high prevalence of Pneumocystis carinii (PC) pneumonia in immunocompromised patients, little is known about the epidemiological characteristics of this infection, and whether the cases of PC pneumonia in immunosuppressed patients are the result of a reactivation of a latent infection or a due to a recent infection is unknown. The aim of this study was to provide information about the epidemiological characteristics of PC pneumonia in a cohort of heart transplant (HT) recipients when compared with the epidemiology of PC infection in a cohort of chronic sputum producers (CSP) representative of the general population of the same geographical area. METHODS We identified all the cases of PC pneumonia in the cohort of 72 subjects who underwent cardiac transplantation at our institution between January 1991 and December 1996 and compared them with the cases of PC infection identified in a non-selected cohort of 34 CSP. This second group was included to obtain an approximation of the frequency of PC carriers in the general population. Identification of PC was accomplished through customary stain techniques and immunofluorescence with monoclonal antibodies. RESULTS Of the 72 HT recipients four (5.5%) developed PC pneumonia, but one had two episodes. Only one had received primary chemoprophylaxis, but developed PC pneumonia 2 months after discontinuing prophylactic therapy. PC pneumonia episodes were produced 53, 102, 230, 181 and 772 days after the moment of transplant, respectively. PC was identified in two (5.8%) of the 34 CSP. No significant differences were found when the accumulative incidences of PC pneumonia in HT patients and PC infection in CSP were compared (P=0.7). CONCLUSIONS The frequency of PC pneumonia among HT patients is the same as the frequency of PC infection in the general population. This observation and the long interval between transplantation and the development of PC pneumonia observed in the study support the hypothesis that the occurrence of PC pneumonia in immunocompromised patients might be from a new infection rather than from the reactivation of latent organisms. Therefore, continuous prophylaxis might be indicated in areas with a high prevalence of PC for patients at highest risk.

Infecciones por VIH-2 y HTLV-I/II en España

Hasta diciembre de 2002, se han identificado en Espana un total de 56, 566 y 109 casos de infeccion por los virus de la leucemia humana T tipos I y II (HTLV-I, HTLV-II) y de la inmunodeficiencia humana tipo 2 (VIH-2), respectivamente. La mayor parte de los sujetos infectados por VIH-2 y HTLV-I corresponden a inmigrantes procedentes de zonas endemicas, o espanoles que han viajado a aquellas regiones o que han mantenido relaciones sexuales con oriundos de ellas. Por el contrario, la infeccion por el HTLV-II predomina entre espanoles adictos a drogas por via parenteral (ADVP) que con frecuencia estan coinfectados por el VIH-1. Entre los sujetos infectados por el HTLV-I, 12 pacientes han desarrollado mielopatia subaguda y cuatro leucemia de celulas T del adulto. Tan solo 20 (18,3%) de los pacientes infectados por el VIH-2 han desarrollado sida. No se ha observado un incremento en la incidencia de la infeccion por el VIH-2 y el HTLV-I en estos anos. Por el contrario, la infeccion por el HTLV-II se ha extendido rapidamente en el colectivo de pacientes infectados por el VIH-1 adictos a drogas por via parenteral (ADVP) en prisiones con una prevalencia del 18% en determinadas carceles espanolas. No obstante, la prevalencia de dicha infeccion sigue siendo baja fuera del ambito carcelario entre los pacientes infectados por el VIH-1 ADVP (4,7%).

Significance of indeterminate reactivity to human T-Cell lymphotropic virus in Western blot analysis of individuals at risk

Current tests to confirm human T-cell lymphotropic virus (HTLV) infection in individuals at risk of retroviral infection commonly yield indeterminate results. To assess the significance of HTLV-seroindeterminate reactivities in a high-risk population, 16 at-risk individuals who had this serologic pattern by Western blot were studied using a polymerase chain reaction (PCR) assay. Human T-cell lymphotropic virus type II infection was confirmed by the presence of virus-specific nucleic acid in four patients. However, PCR analysis was negative in the remaining 12 individuals. These results indicate strongly that all specimens from at-risk individuals with nondiagnostic HTLV reactivity by current Western blot assay should continue to be considered inconclusive, requiring further testing by more sensitive tests.

High prevalence of Pneumocystis jirovecii colonization in Brazilian cystic fibrosis patients.

A high rate of Pneumocystis jirovecii colonization was observed in Brazilian cystic fibrosis (CF) patients (13 out of 34; 38.2%) who underwent bronchoscopy between March 2006 and August 2009 at the Hospital de Clinicas de Porto Alegre, Brazil. Bronchoalveolar lavage samples were collected from these patients and studied by nested PCR amplification of the mitochondrial gene coding for the large subunit ribosomal RNA (mtLSUrDNA). The observed rate of colonization was higher than that reported in European populations. Genotypic characterization of the mtLSUrDNA locus revealed a predominance of the polymorphisms 85C/248C (genotype 1) and 85T/248C (genotype 3), with all samples possessing the wild-type genotype of dihydropteroate synthase. These findings suggest that cystic fibrosis patients could be an important reservoir and source of P. jirovecii infection. Further studies are required to elucidate the role of this common fungal colonization in the evolution of CF patients.

Metagenomic analysis of bronchoalveolar lavage samples from patients with idiopathic interstitial pneumonia and its antagonic relation with Pneumocystis jirovecii colonization.

Idiopathic interstitial pneumonias are interstitial lung diseases of unknown etiology which prognosis is usually fatal. Microbiota associated to bronchoalveolar lavage from 20 patients with negative bacterial cultures was explored by 16S-rDNA PCR-DGGE, showing a clearly negative relation among the presence of P. jirovecii and bacterial colonization. This is the first report of in vivo antagonistic relation among fungi and bacteria.

Usefulness of oropharyngeal washings for identifying Pneumocystis jirovecii carriers.

PNEUMOCYSTIS jirovecii is the causative agent of Pneumocystis pneumonia (PcP), one of the most frequent and severe opportunistic infections in immunocompromised patients (Stringer et al. 2002). The incidence of PcP has decreased among AIDS patients in developed countries due to chemoprophylaxis and highly active anti-retroviral therapy (HAART). However, PcP remains an important cause of morbidity and mortality worldwide (Morris et al. 2004). Today, the interest in P. jirovecii infection is not only confined to patients with AIDS. It also represents a common and serious opportunistic infection in other immunodeficient groups such as those with autoimmune diseases as well as solid organ transplant recipients and cancer patients undergoing immunosuppressive therapy (Calderón et al. 2004a). Recent studies also demonstrated the presence of asymptomatic P. jirovecii colonization in patients with chronic pulmonary diseases (Respaldiza et al. 2005; Vidal et al. 2006). Despite the advances made in understanding human Pneumocystis infection, many aspects about its epidemiology and natural history remain unclear. For decades, diagnosis of PcP has relied on microscopic visualization of organisms in specimens obtained from the lung either by bronchoalveolar lavage (BAL) or by sputum induction. Currently, the ‘‘gold standard’’ for diagnosis of PcP involves using traditional cytochemical stains of BAL fluid and bright-field light microscopy. Fluorescence microscopy using immunofluorescent monoclonal antibodies enables greater sensitivity and specificity and is useful for analyzing induced-sputum samples (Elvin et al. 1988). Polymerase chain reaction amplification of P. jirovecii DNA increases sensitivity of detecting the organism and is used on sputum and BAL specimens containing only small numbers of organisms (Durand-Joly et al. 2005; Leibovitz et al. 1995). However, non-invasive procedures are sometimes needed when bronchoscopy or even sputum induction are difficult to perform, contraindicated, or unpleasant to the patient. Recently, PCR of oral washings was found to be an attractive non-invasive alternative method for diagnosing P. jirovecii infection. Oropharyngeal washings (OW) are obtained by having the patient rinse the mouth and gargle the throat using sterile saline. (Wakefield et al. 1993) first reported detecting P. jirovecii DNA by PCR by analyzing oral wash samples obtained from PcP patients. Subsequently, other workers have shown that oral or oropharyngeal lavage specimens are useful for diagnosing PcP in patients with severe respiratory distress or tendency to bleed who are unable to undergo bronchoscopy (Helweg-Larsen et al. 1997; Martino et al. 1999). The aim of this study was to evaluate PCR methods for efficacy in detecting P. jirovecii by analyzing OW samples from individuals without PcP but might harbor the organism. MATERIAL AND METHODS

Lymphocyte Response in Subjects with Chronic Pulmonary Disease Colonized by Pneumocystis jirovecii

Pneumocystis jirovecii, known also by its interim trinomial name as Pneumocystis carinii f. sp. hominis [1], continues to be one of the most important causes of opportunistic infections in AIDS patients and in HIV-negative immunocompromised patients [2]. The incidence of P. jirovecii pneumonia (PcP) has decreased in AIDS patients in developed countries with the use of specific chemoprophylaxis and, above all, with highly active antiretroviral therapy. In spite of this, PcP is still an important cause of morbidity and mortality in the western world and is a problem that is being identified more and more in developing countries [3]. Nowadays, interest in P. jirovecii infection is not confined to AIDS patients alone; it also represents a common and serious opportunistic infection in HIV-negative immunocompromised patients due to different causes, such as organ transplant recipients [4], patients with autoimmune diseases who receive immunosuppressive therapy [5], or patients with neoplasias, especially in those with lymphoproliferative diseases [6]. On the other hand, pneumonia caused by this microorganism is not limited to immunosuppressed patients; but, it can affect subjects with no apparent immunosuppression, as it has been well documented in recent publications, describing a series of PcP patients without evidence of immunodeficiency [7,8,9]. Moreover immunocompetent subjects without PcP can be colonized by the pathogen. In this sense, Pneumocystis carriage was found in 10–40% of patients with chronic obstructive disease [10–11]. The major predisposing factor for the development of PcP is impaired cell mediatedor humoral immune response [12]. In patients with HIV infection or T cell defects, the CD4þ T lymphocytes have been shown to play a major role in the defense against this infection. In fact PcP often occurs in AIDS patients with a severe lymphopenia and less that 200 CD4þ T lymphocytes/ml [13]. However, it is not known what changes occur in the lymphocyte response in immunocompetent subjects colonized by this pathogen. The aim of this initial study was to provide information on the lymphocyte response in immunocompetent patients who are colonized by P. jirovecii.