Myo5B plays a significant role in the hyphal growth and virulence of the human pathogenic fungus Mucor lusitanicus.

Mucormycosis is an emerging and deadly invasive fungal infection caused by fungi belonging to the Mucorales order. We investigated the myosin superfamily, which encompasses diverse actin-based motor proteins with various cellular functions. Specifically, the role of the Myo5B (ID 179665) protein from the myosin class V family in Mucor lusitanicus was explored by generating silencing phenotypes and null mutants corresponding to the myo5B gene. Silencing fungal transformants exhibited a markedly reduced growth rate and a nearly complete absence of sporulation compared to the wild-type strain. The myo5BΔ null mutant strain displayed atypical characteristics, including abnormally short septa and inflated hyphae. Notably, there were a majority of small yeast-like cells instead of filamentous hyphae in the mutant. These yeast-like cells cannot germinate normally, resulting in a loss of polarity. In vivo virulence assays conducted in the Galleria mellonella invertebrate model revealed that the myo5BΔ mutant strain was avirulent. These findings shed light on the crucial contributions of the Myo5B protein to the dimorphism and pathogenicity of M. lusitanicus. Therefore, the myosin V family is a potential target for future therapeutic interventions aimed at treating mucormycosis.

Analyzing the safety of the parasiticide fungus Mucor circinelloides: first insights on its virulence profile and interactions with the avian gut microbial community.

Parasiticide fungi are considered an accurate, sustainable, and safe solution for the biocontrol of animal gastrointestinal (GI) parasites. This research provides an initial characterization of the virulence of the native parasiticide fungus Mucor circinelloides (FMV-FR1) and an assessment of its impact on birds' gut microbes. The genome of this fungus was sequenced to identify the genes coding for virulence factors. Also, this fungus was checked for the phenotypic expression of proteinase, lecithinase, DNase, gelatinase, hemolysin, and biofilm production. Finally, an in vivo trial was developed based on feeding M. circinelloides spores to laying hens and peacocks three times a week. Bird feces were collected for 3 months, with total genomic DNA being extracted and subjected to long-read 16S and 25S-28S sequencing. Genes coding for an iron permease (FTR1), iron receptors (FOB1 and FOB2), ADP-ribosylation factors (ARFs) (ARF2 and ARF6), and a GTPase (CDC42) were identified in this M. circinelloides genome. Also, this fungus was positive only for lecithinase activity. The field trial revealed a fecal microbiome dominated by Firmicutes and Proteobacteria in laying hens, and Firmicutes and Bacteroidetes in peacocks, whereas the fecal mycobiome of both bird species was mainly composed of Ascomycetes and Basidiomycetes fungi. Bacterial and fungal alpha-diversities did not differ between sampling time points after M. circinelloides administrations (P = 0.62 and P = 0.15, respectively). Although findings from this research suggest the lack of virulence of this M. circinelloides parasiticide isolate, more complementary in vitro and in vivo research is needed to conclude about the safety of its administration to birds, aiming at controlling their GI parasites.IMPORTANCEA previous study revealed that the native Mucor circinelloides isolate (FMV-FR1) can develop parasiticide activity toward coccidia oocysts, one of the most pathogenic GI parasites in birds. However, ensuring its safety for birds is of utmost importance, namely by studying its virulence profile and potential effect on commensal gut microbes. This initial study revealed that although this M. circinelloides isolate had genes coding for four types of virulence factors-iron permease, iron receptors, ADP-ribosylation factors, and GTPase-and only expressed phenotypically the enzyme lecithinase, the administration of its spores to laying hens and peacocks did not interfere with the abundances and diversities of their gut commensal bacteria and fungi. Although overall results suggest the lack of virulence of this M. circinelloides isolate, more complementary research is needed to conclude about the safety of its administration to birds in the scope of parasite biocontrol programs.

Severe mold fungal infections in critically ill patients with COVID-19.

The SARS-CoV-2 pandemic put an unprecedented strain on modern societies and healthcare systems. A significantly higher incidence of invasive fungal co-infections was noted compared with the pre-COVID-19 era, adding new diagnostic and therapeutic challenges in the critical care setting. In the current narrative review, we focus on invasive mold infections caused by Aspergillus and Mucor species in critically ill COVID-19 patients. We discuss up-to-date information on the incidence, pathogenesis, diagnosis and treatment of these mold-COVID-19 co-infections, as well as recommendations on preventive and prophylactic interventions. Traditional risk factors were often not recognized in COVID-19-associated aspergillosis and mucormycosis, highlighting the role of other determinant risk factors. The associated patient outcomes were worse compared with COVID-19 patients without mold co-infection.

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Mucormicosis rinosinusal por mucor hiemalis en una paciente con leucemia mieloide aguda / Rhinosinusal mucormycosis by mucor hiemalis in a patient with acute myeloid leukemia

Se reporta un caso clínico de una paciente femenina de 41 años, con antecedentes de leucemia mieloide aguda (LMA) en remisión. Estudiada por hematología, se confirmó recaída de LMA M4. Se inició quimioterapia. La paciente evolucionó con pancitopenia severa. Presentó dos episodios de neutropenia febril, el primero fue asociado a un absceso glúteo que se trató con antibacterianos, y el segundo a compromiso rinosinusal y úlcera necrótica de punta nasal, columela, tabique, cornete inferior izquierdo y paladar duro. Debido a la clínica e imá- genes radiológicas, se sospechó mucormicosis, por lo que se realizó cirugía con debridación extensa y se inició tratamiento antimicótico con anfotericina B desoxicolato. El cultivo de tejido informó abundante desarrollo de Mucor hiemalis. Se mantuvo pancitopénica durante aproximadamente un mes, siendo diariamente evaluada por un equipo multidisciplinario. Se hicieron varios aseos quirúrgicos, en el último se encontró tejido vital. La paciente completó diez días con anfotericina B desoxicolato y posteriormente se hizo traslape a posaconazol oral. Se realizó mielograma de control que evidenció remisión completa de recaída de LMA. Se dio de alta a su domicilio al día 40 de hospitalización, con hemograma adecuado y tratamiento oral con posaconazol para completar 6 semanas en total.

We report a case of a 41-years-old female patient with a history of acute myeloid leukemia (AML) in remission. Hematology studies confirmed relapse of AML M4. Chemotherapy was started. The patient developed severe pancytopenia. She presented two episodes of febrile neutropenia, the first one was associated with a gluteal abscess that was treated with antibacterials, and the second to rhinosinusal involvement and necrotic ulcer of nasal tip, columella, septum, left inferior turbinate and hard palate. Due to clinical and radiological imaging, mucormycosis was suspected, so surgery was performed with extensive debridement and antifungal treatment with amphotericin B deoxicholate was initiated. Tissue culture reported abundant development of Mucor hiemalis. She remained pancytopenic for approximately one month, being evaluated daily by a multidisciplinary team. Several surgical were made, finding vital tissue in the last perform. The patient completed ten days with amphotericin B deoxicholate and later was overlapped to oral posaconazole. A control myelogram was performed, showing complete remission of AML. She was discharged to her home at day 40 of hospitalization, with adequate blood count and oral treatment with posaconazole to complete 6 weeks in total.