Molecular Diagnosis of Invasive Aspergillosis

Invasive aspergillosis (IA) is a disease that is difficult to manage and is associated with a significantly high morbidity and mortality, caused by different species of the genus Aspergillus, and closely related to immunocompromised patients; thus, it is important to understand the distribution and molecular epidemiology of the species causing this disease. Even though Aspergillus fumigatus sensu stricto is the most common species that cause IA, in recent years, there has been an increase in the number of species in the different sections which makes the diagnosis of this invasive fungal disease a great challenge. Conventional tests for the diagnosis of IA present limitations in sensitivity and specificity, while molecular tests have the potential to improve diagnosis by offering a more sensitive and rapid identification, but they are not yet standardized for reliable use in clinic. Nevertheless, there are some tests for the presumptive diagnosis of aspergillosis which, although are not specific for the identification of species, have been decisive in the case of IA. Among these are the Galactomannan test (GM), the Beta-D-glucan assay and volatile organic compounds (VOCs) testing. In this chapter, the recent advances and challenges in the molecular diagnosis of IA are revised

Genotyping of Leptospira interrogans isolates from Mexican patients

The aim of this study was genotypically characterize Leptospira sp. clinical isolates from Mexico which were previously identified as Leptospira interrogans serovar Pomona (POM) by phenotypic methods. The Random Amplified Polymorphic DNA (RAPD) method was used for DNA amplification with five oligonucleotides. A dendrogram was constructed using the Unweighted Pair Group Method Analysis (UPGMA). During the genotypic characterization, the studied isolates constituted a group which was associated with the reference strain L. interrogans serovar Pomona. The Minimum Spanning Networks (MST) analysis revealed the same cluster between Mexican isolates and the reference strain POM. Clinical isolates identified as L. interrogans serovar POM have a clonal reproduction type, suggesting that this clone is distributed in different regions of Mexico

Usefulness of a multiplex PCR for the rapid identification of Candida glabrata species complex in Mexican clinical isolates

Candida glabrata complex includes three species identified through molecular biology methods: C. glabrata sensu stricto, C. nivariensis and C. bracarensis. In Mexico, the phenotypic methods are still used in the diagnosis; therefore, the presence of C. nivariensis and C. bracarensis among clinical isolates is still unknown. The aim of this study was to evaluate the utility of a multiplex PCR for the identification of the C. glabrata species complex. DNA samples from 92 clinical isolates that were previously identified through phenotypic characteristics as C. glabrata were amplified by four oligonucleotides (UNI-5.8S, GLA-f, BRA-f, and NIV-f) that generate amplicons of 397, 293 and 223-bp corresponding to C. glabrata sensu stricto, C. nivariensis, and C. bracarensis, respectively. The amplicon sequences were used to perform a phylogenetic analysis through the Maximum Likelihood method (MEGA6), including strains and reference sequences of species belonging to C. glabrata complex. In addition, recombination and linkage disequilibrium were estimated (DnaSP version 5.0) for C. glabrata sensu stricto isolates. Eighty-eight isolates generated a 397-bp fragment and only in one isolate a 223-bp amplicon was observed. In the phylogenetic tree, the sequences of 397-bp were grouped with C. glabrata reference sequences, and the sequence of 223-bp was grouped with C. bracarensis reference sequences, corroborating the PCR identification. The number of recombination events for the isolates of C. glabrata sensu stricto was zero, suggesting a clonal population structure. Three isolates that did not amplify any of the expected fragments were identified as Saccharomyces cerevisiae through the sequencing of the D1/D2 domain region within the 28S rDNA gene. The multiplex PCR is a fast, cost-effective and reliable tool that can be used in clinical laboratories to identify C. glabrata complex species

AFLP analysis reveals high genetic diversity but low population structure in Coccidioides posadasiiisolates from Mexico and Argentina

BACKGROUND: Coccidioides immitis and C. posadasii cause coccidioidomycosis, a disease that is endemic to North and South America, but for Central America, the incidence of coccidioidomycosis has not been clearly established. Several studies suggest genetic variability in these fungi; however, little definitive information has been discovered about the variability of Coccidioides fungi in Mexico (MX) and Argentina (AR). Thus, the goals for this work were to study 32 Coccidioides spp. isolates from MX and AR, identify the species of these Coccidioides spp. isolates, analyse their phenotypic variability, examine their genetic variability and investigate the Coccidioides reproductive system and its level of genetic differentiation. METHODS: Coccidioides spp. isolates from MX and AR were taxonomically identified by phylogenetic inference analysis using partial sequences of the Ag2/PRA gene and their phenotypic characteristics analysed. The genetic variability, reproductive system and level of differentiation were estimated using AFLP markers. The level of genetic variability was assessed measuring the percentage of polymorphic loci, number of effective allele, expected heterocygosity and Index of Association (I(A)). The degree of genetic differentiation was determined by AMOVA. Genetic similarities among isolates were estimated using Jaccard index. The UPGMA was used to contsruct the corresponding dendrogram. Finally, a network of haplotypes was built to evaluate the genealogical relationships among AFLP haplotypes. RESULTS: All isolates of Coccidioides spp. from MX and AR were identified as C. posadasii. No phenotypic variability was observed among the C. posadasii isolates from MX and AR. Analyses of genetic diversity and population structure were conducted using AFLP markers. Different estimators of genetic variability indicated that the C. posadasii isolates from MX and AR had high genetic variability. Furthermore, AMOVA, dendrogram and haplotype network showed a small genetic differentiation among the C. posadasii populations analysed from MX and AR. Additionally, the I(A) calculated for the isolates suggested that the species has a recombinant reproductive system. CONCLUSIONS: No phenotypic variability was observed among the C. posadasii isolates from MX and AR. The high genetic variability observed in the isolates from MX and AR and the small genetic differentiation observed among the C. posadasii isolates analysed, suggest that this species could be distributed as a single genetic population in Latin America

Histoplasmosis: retos en el diagnóstico

Histoplasmosis is an infection usually caused by a fungal pathogen that, in most cases, occurs in the respiratory tract, which explains the high frequency of clinical manifestations in the lungs. (1) This mycosis is endemic in the Americas (Mississippi and Ohio River Valley, USA; Central and South America; and the West Indies), while reports in areas of Asia, Africa, Australia, and Oceania are mainly asso­ciated with the pandemic of acquired immune deficiency syndrome (AIDS). In Europe, cases are on the rise because of the speculation of a global distribution of histoplasmosis, and emphasis has been on improving methods for its diagnosis. (2,3)La histoplasmosis es una infección que en la mayoría de los casos ocurre por vía respiratoria, lo cual explica la alta frecuencia de manifestaciones clínicas a nivel pulmonar, y que por lo general es causada por un patógeno fúngico (1). Esta micosis es endémica en el continente americano (valle de los ríos Mississippi y Ohio, EE. UU.; Centro y Sudamérica, y las Antillas), mientras que en áreas de Asia, África, Australia y Oceanía los reportes se deben principalmente a la pandemia del síndrome de inmunodeficiencia adquirida (sida). En Europa los casos vienen en aumento debido a que, a partir de la especulación de una distribución global de la histoplasmosis, se ha enfatizado en mejorar los métodos para su diagnóstico (2,3)

Virulence Attributes in <em>Aspergillus fumigatus</em>

Aspergillus fumigatus is one of the most important opportunistic fungal pathogens. It causes various types of infections in humans, from skin, lung, and allergic infections to invasive infections. However, these stand out because their mortality rate can reach up to 95%. A. fumigatus is a ubiquitous fungus and, therefore, humans are in constant contact with it without major risk, except when there is a predisposing factor on the host, that allows the fungus to penetrate and invade the tissues. It is fascinating how this fungus manages to go from harmless to pathogenic as, in addition to the predisposing factors of the human, multiple attributes of the fungus intervene that favor its growth and survival in the host. Among these virulence attributes are thermotolerance, the ability to evade the immune response, some components of the cell wall, the production of secondary metabolites, compliance with nutritional requirements, and the production of melanin, among others. Furthermore, some of these virulence attributes are interrelated, making understanding the pathogenesis of aspergillosis more complex. This chapter presents a review of some virulence attributes that are known, to date, in A. fumigatus

Uncommon Clinical Presentations of Sporotrichosis: A Two-Case Report

Sporotrichosis is a subcutaneous endemic mycosis caused by species of the Sporothrix schenckii complex. The most common clinical form of the disease is lymphocutaneous, while the fixed cutaneous and disseminated cutaneous forms are rare. Moreover, it is more prevalent in immunocompetent individuals. In this study, we present two cases of sporotrichosis with uncommon clinical forms: fixed cutaneous (Case 1) and disseminated cutaneous (Case 2). Both cases were diagnosed in immunocompetent males from endemic regions in Mexico, who had at least 1 year of evolution without improvement in response to prior nonspecific treatments. The diagnosis of sporotrichosis caused by S. schenckii sensu stricto was established through the isolation of the pathogen and its identification through the amplification of a 331 bp fragment of the gene encoding calmodulin. In both cases, improvement was observed after treatment with potassium iodide. Cases 1 and 2 illustrate the rarity of these clinical forms in individuals residing in endemic areas; hence, it is important to ensure a high index of clinical suspicion for the diagnosis of mycosis, as the differential diagnoses vary widely

Vaccines Against COVID-19: A Review

As a result of the COVID-19 pandemic, various joint efforts have been made to support the creation of vaccines. Different projects have been under development, of which some are in the clinical evaluation stage and others in are in phase III with positive results. The aim of this paper was to describe the current situation of the development and production of vaccines available to the population to facilitate future research and continue developing and proposing ideas for the benefit of the population. So, we carried out a systematic review using databases such as PubMed, ScienceDirect, SciELO, and MEDLINE, including keywords such as &ldquo;vaccines,&rdquo; &ldquo;COVID-19,&rdquo; and &ldquo;SARS-CoV-2&rdquo;. We reviewed the development and production of the anti-COVID vaccine and its different platforms, the background leading to the massive development of these substances, and the most basic immune aspects for a better understanding of their physiological activity and the immune response in those who receive the vaccine. We also analyzed immunization effects in populations with any medical or physiological conditions (such as immunosuppression, people with comorbidities, and pregnancy), as well as the response to immunization with heterologous vaccines and the hybrid immunity (the combination of natural immunity to SARS-CoV-2 with immunity generated by the vaccine). Likewise, we address the current situation in Mexico and its role in managing the vaccination process against SARS-CoV-2 at the national and international levels. There are still many clinical and molecular aspects to be described, such as the duration of active immunity and the development of immunological memory, to mention some of the most important ones. However, due to the short time since the global vaccination roll-out and that it has been progressive (not counting children and people with medical conditions), it is premature to say whether a second vaccination schedule will be necessary for the near future. Thus, it is essential to continue with health measures