Isolation of Clavispora lusitaniae from the Oral Cavity of Immunocompetent Young Adults from the North of Mexico.

The human oral cavity is normally colonized by microorganisms including bacteria, fungi, archaea, viruses and protozoa. The aim of this study was to determine the frequency of Candida spp., in de oral cavity in a group of medical students from the north of Mexico. Oral sample were obtained from 240 healthy students. The specimens were analyzed by traditional microbiology cultures and DNA sequencing. Candida spp., grew in Sabouraud dextrose agar from 57 samples and subsequently were isolated and phenotyped. The definitive identification to the species level was done by sequence analysis. The yeasts were identified as follow: 28 Clavispora lusitaniae, 20 Candida albicans, 5 Pichia kudriavzevii and 4 Candida parapsilosis. Our findings revealed that 23.75% of the healthy population has a potential pathogen in their mouth. Surprisingly, C. albicans is not the predominant yeast; instead other non-Candida species are the colonizers of the oral cavity as normal microbiota. C. lusitaniae is considered an emerging opportunistic pathogen in immunosuppressive patients. This paper pretends to highlight the presence of this yeast in the oral cavity in immunocompetent young adults. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01145-x.

Species distribution and antifungal susceptibility profiles of clinical and environmental Fusarium isolates from Mexico: A multicenter study.

Fusarium spp. has emerged as an opportunistic etiological agent with clinical manifestations varying from localized infections to deep-seated systemic disease. It is also a phytopathogen of economic impact. There are few reports on the species diversity of this genus, and no comprehensive studies on the epidemiology nor the antifungal susceptibility of Fusarium in Mexico. The present multicentric study aims to shed light on the species distribution and antifungal susceptibility patterns of 116 strains of Fusarium isolated from clinical and environmental samples. Isolates were identified by standard phenotypic characteristics and by sequencing of the ITS (internal transcribed spacer), TEF1 (translation elongation factor 1-α), RPB2 (RNA polymerase II core subunit), and/or CAM1 (calmodulin) regions. Susceptibility tests were carried out against 15 antifungals of clinical and agricultural use. Regarding Fusarium distribution, we identified 27 species belonging to eight different species complexes. The most frequently isolated species for both clinical and environmental samples were F. falciforme (34%), F. oxysporum sensu stricto (12%), F. keratoplasticum (8%), and F. solani sensu stricto (8%). All Fusarium isolates showed minimum inhibitory concentrations (MICs) equal to or above the maximum concentration evaluated for fluconazole, 5-fluocytosine, caspofungin, micafungin, and anidulafungin. All isolates had a MIC of ≤16 µg/mL for voriconazole, with a mode of 4 µg/mL. F. verticillioides appeared to be the most susceptible to all antifungals tested.

Severe strongyloidiasis: a systematic review and meta-analysis of 339 cases.

Strongyloidiasis is a parasitosis representing a significant public health problem in tropical countries. It is often asymptomatic in immunocompetent individuals but its mortality rate increases to approximately 87% in severe forms of the disease. We conducted a systematic review, including case reports and case series, of Strongyloides hyperinfection and dissemination from 1998 to 2020 searching PubMed, EBSCO and SciELO. Cases that met the inclusion criteria of the Preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist were analysed. Statistical analysis was performed using Fisher's exact test and Student's t-test and a Bonferroni correction for all the significant values. A total of 339 cases were included in this review. The mortality rate was 44.83%. The presence of infectious complications, septic shock and a lack of treatment were risk factors for a fatal outcome. Eosinophilia and ivermectin treatment were associated with an improved outcome.

Recent Antifungal Pipeline Developments against Candida auris: A Systematic Review.

The alarming spread and impact of multidrug-resistant Candida auris infections alongside the limited therapeutic options have prompted the development of new antifungals. These promising agents are currently in different stages of development, offering novel dosing regimens and mechanisms of action. A systematic search in MEDLINE, EMBASE, Web of Science, and Scopus up to 27 June 2022 was conducted to find relevant articles reporting data of in vitro activity and in vivo efficacy of investigational antifungals against C. auris. These included new additions to existing antifungal classes (rezafungin and opelconazole), first-in-class drugs such as ibrexafungerp, manogepix/fosmanogepix, olorofim and tetrazoles (quilseconazole, oteseconazole and VT-1598), as well as other innovative agents like ATI-2307, MGCD290 and VL-2397. From 592 articles retrieved in the primary search, 27 met the eligibility criteria. The most studied agent was manogepix/fosmanogepix (overall MIC90: 0.03 mg/L), followed by ibrexafungerp (overall MIC90: 1 mg/L) and rezafungin (overall MIC mode: 0.25 mg/L), while VT-1598 and ATI-2307 were the least explored drugs against C. auris. All these compounds demonstrated significant improvements in survival and reduction in tissue fungal burden on neutropenic animal models of candidemia due to C. auris. Continual efforts towards the discovery of new treatments against this multidrug-resistant fungus are essential.

Physiological characterization and molecular identification of some rare yeast species causing onychomycosis.

INTRODUCTION: Onychomycosis are infections with a variety of etiological agents. Although dermatophytes are responsible for most infections, yeasts are gaining importance as agents of these pathologies. The use of antifungals has increased the incidence of what had been considered rare or novel pathogens. We reidentify three rare yeasts from a culture collection of onychomycosis agents by matrix-assisted laser desorption/ionization time of flight/mass spectrometry (MALDI-TOF/MS) and sequencing the internal transcribed spacer (ITS) regions or the intergenic spacer (IGS) 1 region of ribosomal DNA (rDNA), and present their enzymatic and antifungal susceptibility profiles. MATERIAL AND METHODS: We performed a phenotypical characterization and molecular identification of five yeast isolates. We tested the urease, gelatinase, DNase, phospholipase, protease, and esterase activities, as well as the hemolytic activity. We evaluated the antifungal susceptibility to amphotericin B, fluconazole, anidulafungin and caspofungin. RESULTS: Phenotypic methods could not identify the isolates. MALDI-TOF/MS was able to properly identify Candida duobushameulonii. The five isolates were successfully identified by sequence analysis as Candida duobushaemulonii, Meyerozyma caribbica and Cutaneotrichosporon dermatis. Candida duobushameulonii showed hemolytic, phospholipase, and protease activities. Meyerozyma caribbica was positive for gelatinase and protease activities. All antifungals exhibited minimum inhibitory concentrations (MICs) ≤2µg/mL against both species. The three isolates of Cutaneotrichosporon dermatis showed urease, DNase, and esterase activities, and resistance to echinocandins (MICs ≥8µg/mL), while amphotericin B and fluconazole exhibited low MICs against these isolates (0.50-2µg/mL). DISCUSSION: Sequencing of the ITS or IGS1 regions of rDNA remains the best method for identifying cryptic species over other commercially available systems. More reports are needed to define the enzymatic and antifungal profiles for these species. This is the first report of Meyerozyma caribbica and Cutaneotrichosporon dermatis as etiological agents of onychomycosis.

A comparative study of extracellular enzymes from chromoblastomycosis agents reveals the potential association of phospholipase with the severity of the lesions.

Chromoblastomycosis is a chronic, progressive subcutaneous mycosis that is endemic in tropical and subtropical countries. Cladophialophora carrionii and Fonsecaea pedrosoi are prevalent etiological agents. The potential role of the proteolytic activity of extracellular enzymes in these fungi and its relationship with the pathogenesis of the disease has not been proven. Some phenotypic traits have been associated with the virulence of other fungi; i.e., their different rate of protease, phospholipase, and esterase excretion, melanin, and thermotolerance. The aim of this study was the identification of extracellular enzymes that could be considered virulence markers of chromoblastomycosis agents. Therefore, we tested 29 C. carrionii and 11 F. pedrosoi clinical isolates to determine their hydrolytic and physiologic characteristics. All the tested isolates grew at a range of 30°-37 °C; except 2 strains of F. pedrosoi that grew slowly at 40 °C. We noticed that the hydrolytic capabilities of the tested isolates were positive for urea hydrolysis in almost all, while both strains were negative for DNase, hemolysin, and gelatin. C. carrionii and F. pedrosoi had phospholipase and esterase activity. These findings were similar for most isolates. All strains showed an association between phospholipase activity and moderate to severe lesions. However, only in F. pedrosoi isolates, the association remains significant. We conclude that the different enzymatic production reported here may be linked to the clinical manifestations of these pathologies. Notwithstanding, the influence of other virulence factors is not excluded.

In vitro inhibitory activity of sertraline against clinical isolates of Sporothrix schenckii / Actividad inhibitoria in vitro de la sertralina frente a aislamientos clínicos de Sporothrix schenckii

Background: Sertraline (SRT) is an antidepressant that has proven its activity in vitro against Cryptococcus, Coccidioides, Trichosporon and other fungi. Disseminated sporotrichosis, although rare, has a high mortality and its treatment is difficult and prolonged, often relying in combining two or more antifungals. Aims: In our study we evaluate the antifungal activity of SRT, alone and in combination with itraconazole (ITC), voriconazole (VRC) and amphotericin B (AMB), against 15 clinical isolates of Sporothrix schenckii. Methods: We used the broth microdilution method as described by the CLSI to test the susceptibility to antifungals, and the checkerboard microdilution method to evaluate drug interactions. Results: The minimum inhibitory concentration (MIC) with SRT was in the range of 4-8μg/ml, while for AMB, VRC and ITC were 0.5-4μg/ml, 0.5-8μg/ml and 0.125-2μg/ml, respectively. In addition, SRT showed synergy with ITC in one strain, mainly additivity with VRC, and indifference with AMB in others. Conclusions: The MIC values with SRT for the isolates studied show the potential role of this drug as an adjuvant in the treatment of sporotrichosis, especially in disseminated or complicated cases

Antecedentes: La sertralina (SRT) es un antidepresivo que ha demostrado actividad in vitro contra Cryptococcus, Coccidioides, Trichosporon y otros hongos. La esporotricosis diseminada, aunque rara, tiene una mortalidad elevada y su tratamiento es complicado, requiriendo, a menudo, la combinación de dos o más antifúngicos. Objetivos: En este estudio evaluamos la actividad antifúngica de SRT, sola y en combinación con itraconazol (ITC), voriconazol (VRC) y anfotericina B (AMB), frente a 15 aislamientos clínicos de Sporothrix schenckii. Métodos: Se usó la técnica de microdilución en caldo para evaluar la sensibilidad a los antifúngicos y el método de tablero de damas para las interacciones entre estos fármacos. Resultados: La concentración mínima inhibitoria (CMI) de SRT estuvo en el rango de 4-8μg/ml, mientras que para AMB, VRC e ITC fue de 0,5-4 μg/ml, 0,5-8 μg/ml y 0,125-2 μg/ml, respectivamente. La SRT mostró sinergia con ITC frente a una cepa, efecto aditivo principalmente con VRC, e indiferencia con AMB. Conclusiones: Los valores de la CMI de SRT para los aislamientos ensayados son indicativos del potencial de este fármaco como adyuvante en el tratamiento de la esporotricosis, especialmente en casos complicados o de enfermedad diseminada

In vitro inhibitory activity of sertraline against clinical isolates of Sporothrix schenckii.

BACKGROUND: Sertraline (SRT) is an antidepressant that has proven its activity in vitro against Cryptococcus, Coccidioides, Trichosporon and other fungi. Disseminated sporotrichosis, although rare, has a high mortality and its treatment is difficult and prolonged, often relying in combining two or more antifungals. AIMS: In our study we evaluate the antifungal activity of SRT, alone and in combination with itraconazole (ITC), voriconazole (VRC) and amphotericin B (AMB), against 15 clinical isolates of Sporothrix schenckii. METHODS: We used the broth microdilution method as described by the CLSI to test the susceptibility to antifungals, and the checkerboard microdilution method to evaluate drug interactions. RESULTS: The minimum inhibitory concentration (MIC) with SRT was in the range of 4-8µg/ml, while for AMB, VRC and ITC were 0.5-4µg/ml, 0.5-8µg/ml and 0.125-2µg/ml, respectively. In addition, SRT showed synergy with ITC in one strain, mainly additivity with VRC, and indifference with AMB in others. CONCLUSIONS: The MIC values with SRT for the isolates studied show the potential role of this drug as an adjuvant in the treatment of sporotrichosis, especially in disseminated or complicated cases.

In vitro lytic activity and antifungal susceptibility of infrequently isolated yeasts.

Non-albicans Candida species have acquired relevance in the last decades as a cause of serious disease. The virulence factors and antifungal susceptibility of these rare pathogens remain largely unrecognized. We examined a total of 50 yeast isolates corresponding to 11 different infrequently isolated yeast species for their in vitro enzymatic profile and susceptibility pattern as first-line antifungals. We found aspartyl protease activity for 100% of the isolates tested as well as variable DNAse, hemolysin, phospholipase and esterase activities. All strains had low MICs for amphotericin B and showed a variable response to fluconazole (0.125-32 µg/mL) and the echinocandins tested (0.25-> 8 µg/mL).

In vitro virulence determinants, comparative pathogenicity of Diutina (Candida) mesorugosa clinical isolates and literature review of the D. rugosa complex.

Opportunistic mycoses by yeasts have increased considerably in the last three decades. Although Candida albicans is considered one of the most important causes of nosocomial infections, there is a recent shift to non-albicans Candida species as the most frequently isolated yeasts in particular risk groups. Diutina rugosa (formerly Candida rugosa) is a complex that includes four species: D. rugosa sensu stricto, D. neorugosa, D. pseudorugosa, and D. mesorugosa, and they are estimated to represent 0.2% of all Candida clinical isolates. In this study, we analyze nine clinical isolates of D. mesorugosa with focus on the virulence determinants and pathogenicity of the species by means of a Galleria mellonella survival model. Overall, we detected very strong aspartyl-protease and esterase activities. In contrast, both DNase and hemolysin activities were evident in only two of the isolates. None of the isolates was positive for phospholipase activity. All isolates studied were able to form biofilm after 72 h of incubation in a robust manner when compared with the C. albicans strain used as control. Susceptibility testing showed minimum inhibitory concentrations (MICs) ≤1 µg/mL for amphotericin B in all isolates tested. Eight out of nine of the isolates had MICs ≤2 µg/mL for fluconazole. All isolates were resistant to both anidulafungin and caspofungin (MICs ≥1 µg/mL). We found a significant difference (P < 0.0001) amongst the survival curves for the different D. mesorugosa isolates in the Galleria mellonella survival model. Strains HPM309 and H259 produced an acute infection and exhibited the highest virulence, whereas the D. mesorugosa isolates 99-480 and DM17 proved to be the less virulent strains.

Molecular Identification, Antifungal Susceptibility, and Geographic Origin of Clinical Strains of Sporothrix schenckii Complex in Mexico.

Sporotrichosis is a subcutaneous mycosis caused by Sporothrix schenckii complex. The disease has been reported worldwide. However, the incidence of the etiological agent varies in its geographic distribution. We studied 39 clinical isolates of Sporothrix schenckii from diverse regions in Mexico, collected from 1998 to 2016. Molecular identification was performed by sequence analysis of the partial calmodulin gene. In vitro antifungal susceptibility to amphotericin B (AMB), itraconazole (ITC), voriconazole (VRC), posaconazole (PSC), fluconazole (FLC), terbinafine (TRB), caspofungin (CSF), anidulafungin (ANF), and micafungin (MCF) was evaluated. Thirty-eight isolates of S. schenckii complex were divided into five supported clades in a phylogenetic tree. The predominant clinical form was lymphocutaneous (92.3%), fixed cutaneous (5.1%), and disseminated (2.5%). Terbinafine exhibited the best in vitro antifungal activity, while fluconazole was ineffective against Sporothrix schenckii complex. Our results showed diverse geographic distribution of clinical isolates in eight states; definitive identification was done by CAL gen PCR-sequencing. In Mexico, S. schenckii is considered to be an etiological agent of human sporotrichosis cases, and lymphocutaneous is the most prevalent form of the disease. This study revealed four clades of S. schenckiisensu stricto by phylogenetic analysis. Furthermore, we report one case of S. globosa isolated from human origin from the North of Mexico.

Molecular identification of unusual Mycetoma agents isolated from patients in Venezuela.

Mycetoma is a chronic granulomatous, subcutaneous disease endemic in tropical and subtropical countries. It is currently a health problem in rural areas of Africa, Asia and South America. Nine cases of mycetoma were analysed in a retrospective study. All isolates were identified by morphological features. The level of species identification was reached by molecular tools. Definitive identification of fungi was performed using sequence analysis of the ITS of the ribosomal DNA region and the ribosomal large-subunit D1/D2. Identification of actinomycetes was accomplished by the 16S rRNA gene sequence. Six unusual clinical isolates were identified: Aspergillus ustus, Cyphellophora oxyspora, Exophiala oligosperma, Madurella pseudomycetomatis, Nocardia farcinica and Nocardia wallacei. The prevalence of mycetoma in Venezuela remains unknown. This study represents the first report in the literature of mycetoma caused by unusual pathogens identified by molecular techniques.