PbGP43 Genotyping Using Paraffin-Embedded Biopsies of Human Paracoccidioidomycosis Reveals a Genetically Distinct Lineage in the Paracoccidioides brasiliensis Complex.

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by a group of cryptic species embedded in the Paracoccidioides brasiliensis complex and Paracoccidioides lutzii. Four species were recently inferred to belong to the P. brasiliensis complex, but the high genetic diversity found in both human and environmental samples have suggested that the number of lineages may be higher. This study aimed to assess the 43-kilodalton glycoprotein genotypes (PbGP43) in paraffin-embedded samples from PCM patients to infer the phylogenetic lineages of the P. brasiliensis complex responsible for causing the infection. Formalin-fixed, paraffin-embedded (FFPE) tissue samples from patients with histopathological diagnosis of PCM were analyzed. DNAs were extracted and amplified for a region of the second exon of the PbGP43 gene. Products were sequenced and aligned with other PbGP43 sequences available. A haplotype network and the phylogenetic relationships among sequences were inferred. Amino acid substitutions were investigated regarding the potential to modify physicochemical properties in the proteins. Six phylogenetic lineages were identified as belonging to the P. brasiliensis complex. Two lineages did not group with any of the four recognized species of the complex, and, interestingly, one of them comprised only FFPE samples. A coinfection involving two lineages was found. Five parsimony-informative sites were identified and three of them showed radical non-synonymous substitutions with the potential to promote changes in the protein. This study expands the knowledge regarding the genetic diversity existing in the P. brasiliensis complex and shows the potential of FFPE samples in species identification and in detecting coinfections.

Genetic diversity of Pneumocystis jirovecii from a cluster of cases of pneumonia in renal transplant patients: Cross-sectional study.

Pneumocystis jirovecii can cause severe potentially life-threatening pneumonia (PCP) in kidney transplant patients. Prophylaxis of patients against PCP in this setting is usually performed during 6 months after transplantation. The aim of this study is to describe the molecular epidemiology of a cluster of PCP in renal transplant recipients in Brazil. Renal transplant patients who developed PCP between May and December 2011 had their formalin-fixed paraffin-embedded (FFPE) lung biopsy samples analysed. Pneumocystis jirovecii 23S mitochondrial large subunit of ribosomal RNA (23S mtLSU-rRNA), 26S rRNA, and dihydropteroate synthase (DHPS) genes were amplified by polymerase chain reaction (PCR), sequenced, and analysed for genetic variation. During the study period, 17 patients developed PCP (only four infections were documented within the first year after transplantation) and six (35.3%) died. Thirty FFPE samples from 11 patients, including one external control HIV-infected patient, had fungal DNA successfully extracted for further amplification and sequencing for all three genes. A total of five genotypes were identified among the 10 infected patients. Of note, four patients were infected by more than one genotype and seven patients were infected by the same genotype. DNA extracted from FFPE samples can be used for genotyping; this approach allowed us to demonstrate that multiple P. jirovecii strains were responsible for this cluster, and one genotype was found infecting seven patients. The knowledge of the causative agents of PCP may help to develop new initiatives for control and prevention of PCP among patients undergoing renal transplant and improve routine PCP prophylaxis.

Development of a Multiplex qPCR Assay for Fast Detection and Differentiation of Paracoccidioidomycosis Agents.

Classic paracoccidioidomycosis (PCM) is a potentially deadly neglected tropical systemic mycosis caused by members of the Paracoccidioides brasiliensis complex (P. brasiliensis s. str., P. americana, P. restrepiensis, and P. venezuelensis) and P. lutzii. The laboratorial diagnosis of PCM relies on observing pathognomonic structures such as the "steering wheel" or "Mickey Mouse" shape in the direct mycological examination, fresh biopsied tissue in 10% KOH, histopathological analysis, and/or the isolation of the fungus in culture. However, these procedures are time-consuming and do not allow for the speciation of Paracoccidioides due to overlapping morphologies. Here, we propose a new one-tube multiplex probe-based qPCR assay to detect and recognize agents of the P. brasiliensis complex and P. lutzii. Primers (Paracoco-F and Paracoco-R) and TaqMan probes (PbraCx-Fam, Plu-Ned, and Paracoco-Vic) were developed to target the rDNA (ITS2/28S) in the Paracoccidioides genome. A panel of 77 Paracoccidioides isolates revealed a 100% specificity (AUC = 1.0, 95% CI 0.964-1.000, p < 0.0001) without cross-reacting with other medically relevant fungi or human and murine DNA. The lower limit of detection was 10 fg of gDNA and three copies of the partial rDNA amplicon. Speciation using qPCR was in perfect agreement with AFLP and TUB1-RFLP markers (kappa = 1.0). As a proof of concept, we assessed a panel of 16 formalin-fixed and paraffin-embedded specimens from histopathologically confirmed PCM patients to reveal a significant sensitivity of 81.25% and specificity of 100% (AUC = 0.906 ± 0.05, 95% CI = 0.756-0.979, p < 0.0001, Youden index J = 0.8125). Our assay achieved maximum sensitivity (100%) and specificity (100%) using fresh clinical samples (n = 9) such as sputum, bronchoalveolar lavage, and tissue fragments from PCM patients (AUC = 1.0, 95% CI 0.872-1.000, p < 0.0001, Youden index J = 1.0). Overall, our qPCR assay simplifies the molecular diagnosis of PCM and can be easily implemented in any routine laboratory, decreasing a critical bottleneck for the early treatment of PCM patients across a vast area of the Americas.

A New Duplex PCR-Assay for the Detection and Identification of Paracoccidioides Species.

Paracoccidioidomycosis (PCM) is a life-threatening systemic fungal infection caused by members of the Paracoccidioides brasiliensis complex and P. lutzii. Routine diagnoses of PCM down to the species level using classical mycological approaches are unspecific due to overlapping phenotypes. There is an urgent need for specific, sensitive, and cost-effective molecular tools to diagnose PCM. Variation among the exon-2 of the gp43 gene was exploited to design species-specific primer pairs to discriminate between members of the P. brasiliensis complex and P. lutzii in a duplex PCR assay. Primer-BLAST searches revealed highly species-specific primers, and no significant region of homology was found against DNA databases except for Paracoccidioides species. Primers PbraCx-F and PbraCx-R targeting P. brasiliensis DNA produced an amplicon of 308 bp, while primers Plu-F and Plu-R targeting P. lutzii DNA generated an amplicon of 142 bp. The lower limit of detection for our duplex PCR assay was 1 pg of gDNA. A panel of 62 Paracoccidioides revealed 100% specificity (AUC = 1.000, 95%CI 0.972-1.000, p < 0.0001) without cross-reacting with other medically relevant fungi or human DNA. As a proof of concept, we demonstrated the accurate identification of the P. brasiliensis complex (n = 7) or P. lutzii (n = 6) from a broad range of formalin-fixed, paraffin-embedded (FFPE) tissues of PCM patient's organs. In four cases, FFPE PCR results confirmed, for the first time, co-infection due to P. brasiliensis (S1) and P. lutzii in the same biopsy. Our duplex PCR assay is useful to detect and differentiate members of the P. brasiliensis complex and P. lutzii, providing clinical laboratories with an important tool to be applied routinely, especially in atypical cases such as those featuring negative serology and positive mycological examination of clinical specimens as well as for the investigation of putative co-infection cases. This will likely benefit thousands of infected patients every year in a wide area of the Americas.

Correlation between clinical outcome and tissue inflammatory response in kidney transplant recipients with cryptococcosis.

Cryptococcosis is the second most common invasive fungal infection reported in renal transplant recipients. Tissue granulomatous inflammation is necessary to contain Cryptococcus infection. This study aims to analyze the granuloma patterns and in situ expression of regulatory T (Treg) immune response in tissue samples from 12 renal transplant recipients with cryptococcosis. Fungal isolates were molecularly identified as Cryptococcus neoformans species complex. A detailed characterization of granulomas in tissue samples from 12 kidney transplant recipients with cryptococcosis was described by checking six lung and six skin biopsies by conventional histology and for immunohistochemical detection of CD4 and Treg markers: forkhead box P3 (FoxP3), interleukin (IL)-10 and transforming-growth factor (TGF)-ß. Granulomas were classified as compact, loose or mixed. Patients with mixed (n = 4) and compact (n = 3) granulomatous inflammation patterns were associated with a better prognosis and presented a higher number of CD4+FoxP3+T cells compared to the group of patients with loose granulomas. In counterpart, three out of five patients with loose granulomas died with cryptococcosis. We suggest that Treg may have a protective role in the tissue response to Cryptococcus infection given its association with compact and mixed granulomas in patients with better clinical outcomes.

Detection of gp43 of Paracoccidioides brasiliensis by the loop-mediated isothermal amplification (LAMP) method.

Paracoccidioidomycosis is a deep mycosis caused by the thermo-dependent dimorphic fungus Paracoccidioides brasiliensis and is prevalent in Latin American countries. We detected the species specific gp43 gene of P. brasiliensis by loop-mediated isothermal amplification (LAMP) in 22 clinical and seven armadillo-derived isolates. The amplified DNA appeared as a ladder with a specific banding pattern. The advantage of the LAMP method is speed; only 3 h were necessary for identification of the organism and diagnosis of the disease. We were also able to obtain positive results from DNA extracted from a paraffin-embedded tissue sample of paracoccidioidomycosis, suggesting that this method may achieve clinical application in the near future.

Genotyping of Paracoccidioides brasiliensis directly from paraffin embedded tissue.

Based on polymorphisms of the gp43 precursor gene, genotyping of Paracoccidioides brasiliensis was achieved in 6 out of 10 paraffin-embedded tissue samples by modifying a nested PCR procedure used in the diagnosis of the fungal infection. Nine of the samples originated in Brazil. Three sequences were identical to a previously published consensus sequence identifying the P. brasiliensis isolates as members of the formerly named species 1. In contrast, two sequences revealed substitutions identical to isolates of the phylogenetic species 2. Applying the method to a lung biopsy from a proven case of paracoccidioidomycosis diagnosed in Austria, the gp43 sequence revealed substitutions so far only described in five strains originating from Venezuela. Combining travel history and result of this new method, the most probable country of origin of the infections could be identified. Since endemic mycosis are often diagnosed by histopathology only, our method could help to extend epidemiological studies of paracoccidioidomycosis.