Mucormicosis asociada a COVID-19: revisión de la literatura para odontólogos / COVID-19 associated mucormycosis: a literature review for dentists

La mucormicosis es una infección fúngica rara, con alta morbilidad y mortalidad. Se presenta principalmente en pa- cientes con diabetes mellitus no controlada, inmunocompro- metidos, con tratamiento crónicos con esteroides, entre otros. Actualmente, se cree que la pandemia de COVID-19 y los tratamientos con corticosteroides podrían estar implicados en el aumento de casos de esta micosis. Este hongo invade el sistema vascular, ocluyendo el flujo sanguíneo arterial y generando una rápida trombosis e isque- mia, lo que provoca la necrosis de los tejidos duros y blandos, con invasión rápida a los tejidos circundantes. Hay varias formas clínicas. En la cavidad bucal se presenta la variante rino-orbito-cerebral, que afecta el paladar en forma de lesión eritematosa o grisácea que puede progresar hacia la formación de una masa necrótica o ulceración con muy escaso sangrado de mucosa. Se manifiesta con síntomas típicos de una rinosinusitis con fiebre y dolor en las piezas dentarias superiores. El tratamiento consta de tres pilares fundamentales: el diagnóstico, un manejo adecuado de las comorbilidades y la combinación de las terapias antifúngica y quirúrgica. Desde el año 2020, la mucormicosis asociada a COVID-19 pasó a ser un evento de notificación obligatoria inmediata al Sistema Nacional de Vigilancia de la Salud (SNVS2.0) me- diante el Sistema Integrado de Información Sanitaria Argen- tina (SISA). Es importante destacar que se han reportado casos de mu- cormicosis luego de extracciones dentales; lo que impulsa a afianzar los conocimientos sobre esta enfermedad, extremar las medidas preventivas e incentivar el diagnóstico precoz en la atención odontológica, debido a la rapidez en la evolución de la patología (AU))

Mucormycosis is a rare fungal infection, with high mor- bidity and mortality. It occurs mainly in patients with uncon- trolled diabetes mellitus, immunocompromised, on chronic treatment with steroids, among others. Currently, it is believed that the COVID-19 pandemic and the corticosteroid treatments could be one of the causes of increased cases. This fungus invades the vascular system, occluding arteri- al blood flow and generating rapid thrombosis and ischemia, which causes necrosis of hard and soft tissues, with rapid in- vasion to the surrounding tissues. There are several clinical forms. In the oral cavity, the rhino-orbito-cerebral variant presents itself affecting the pal- ate in the form of an erythematous or grayish lesion that can progress towards the formation of a necrotic mass or ulcera- tion with very little mucosal bleeding. It manifests itself with typical symptoms of rhinosinusitis, with fever and pain in the upper teeth. The treatment consists of three fundamental pillars: diag- nosis, proper management of comorbidities and the combina- tion of antifungal and surgical therapies. Since 2020, COVID-19 associated mucormycosis became an event of mandatory immediate notification to the National Health Surveillance System (SNVS2.0,) through the Argentina Integrated Health Information System (SISA). It is important to emphasize that mucormycosis cases had been reported following tooth extractions, which drives to strengthen knowledge about this disease, extreme preventive measures and encourage early diagnosis in dental care, due to the speed of the evolution of the pathology (AU))

Immunoinformatic Design of a Multivalent Peptide Vaccine Against Mucormycosis: Targeting FTR1 Protein of Major Causative Fungi.

Mucormycosis is a potentially fatal illness that arises in immunocompromised people due to diabetic ketoacidosis, neutropenia, organ transplantation, and elevated serum levels of accessible iron. The sudden spread of mucormycosis in COVID-19 patients engendered massive concern worldwide. Comorbidities including diabetes, cancer, steroid-based medications, long-term ventilation, and increased ferritin serum concentration in COVID-19 patients trigger favorable fungi growth that in turn effectuate mucormycosis. The necessity of FTR1 gene-encoded ferrous permease for host iron acquisition by fungi has been found in different studies recently. Thus, targeting the transit component could be a potential solution. Unfortunately, no appropriate antifungal vaccine has been constructed as of yet. To date, mucormycosis has been treated with antiviral therapy and surgical treatment only. Thus, in this study, the FTR1 protein has been targeted to design a convenient and novel epitope-based vaccine with the help of immunoinformatics against four different virulent fungal species. Furthermore, the vaccine was constructed using 8 CTL, 2 HTL, and 1 LBL epitopes that were found to be highly antigenic, non-allergenic, non-toxic, and fully conserved among the fungi under consideration. The vaccine has very reassuring stability due to its high pI value of 9.97, conclusive of a basic range. The vaccine was then subjected to molecular docking, molecular dynamics, and immune simulation studies to confirm the biological environment's safety, efficacy, and stability. The vaccine constructs were found to be safe in addition to being effective. Finally, we used in-silico cloning to develop an effective strategy for vaccine mass production. The designed vaccine will be a potential therapeutic not only to control mucormycosis in COVID-19 patients but also be effective in general mucormycosis events. However, further in vitro, and in vivo testing is needed to confirm the vaccine's safety and efficacy in controlling fungal infections. If successful, this vaccine could provide a low-cost and effective method of preventing the spread of mucormycosis worldwide.

In Silico Designing of a Multitope Vaccine against Rhizopus microsporus with Potential Activity against Other Mucormycosis Causing Fungi.

During the current era of the COVID-19 pandemic, the dissemination of Mucorales has been reported globally, with elevated rates of infection in India, and because of the high rate of mortality and morbidity, designing an effective vaccine against mucormycosis is a major health priority, especially for immunocompromised patients. In the current study, we studied shared Mucorales proteins, which have been reported as virulence factors, and after analysis of several virulent proteins for their antigenicity and subcellular localization, we selected spore coat (CotH) and serine protease (SP) proteins as the targets of epitope mapping. The current study proposes a vaccine constructed based on top-ranking cytotoxic T lymphocyte (CTL), helper T lymphocyte (HTL), and B cell lymphocyte (BCL) epitopes from filtered proteins. In addition to the selected epitopes, ß-defensins adjuvant and PADRE peptide were included in the constructed vaccine to improve the stimulated immune response. Computational tools were used to estimate the physicochemical and immunological features of the proposed vaccine and validate its binding with TLR-2, where the output data of these assessments potentiate the probability of the constructed vaccine to stimulate a specific immune response against mucormycosis. Here, we demonstrate the approach of potential vaccine construction and assessment through computational tools, and to the best of our knowledge, this is the first study of a proposed vaccine against mucormycosis based on the immunoinformatics approach.

Absence of Case of Mucormycosis (March 2020-May 2021) under strict protocol driven management care in a COVID-19 specific tertiary care intensive care unit.

AIMS: With a sudden increase in cases of mucormycosis seen in Covid -19 patients, we conducted a retrospective analysis of all admitted patients in a tertiary care covid-19 hospital looking at incidence of mucormycosis. METHODS: Intensive care unit daily rounds data stored in an electronic format was retrieved by one of the consultants, looking for incidence of mucormycosis, diabetes mellitus, adherence to protocol for steroid use, glycemic control and use of monoclonal antibodies. Also, patients follow up data base of post covid Outpatients Department was searched for cases of mucormycosis. RESULTS: A total of 5248 patients were admitted between March 2020 to May 2021, of which 1027 were in ICU and 4221 in wards. Of the 1027 patients admitted in Intensive care unit, 915 received steroids and 417 had diabetes as existing co-morbidity. No case of mucormycosis was reported during the stay in the hospital and during immediate outpatient department follow up. The low dose steroids were administered as per state government protocol for treating COVID 19, a nurse driven strict glycemic control regime (blood glucose level was maintained between 140 and 180 mg/dl through the admission in ICU and was achieved consistently in 842 (82%) patients, followed along with minimal use of other immunomodulatory like monoclonal antibodies. CONCLUSION: A strict adherence to protocol of low dose steroids coupled with strict glycemic control helped in eliminating the risk and incidence of mucormycosis in a tertiary care dedicated covid-19 hospital.

Mucoricin is a ricin-like toxin that is critical for the pathogenesis of mucormycosis.

Fungi of the order Mucorales cause mucormycosis, a lethal infection with an incompletely understood pathogenesis. We demonstrate that Mucorales fungi produce a toxin, which plays a central role in virulence. Polyclonal antibodies against this toxin inhibit its ability to damage human cells in vitro and prevent hypovolemic shock, organ necrosis and death in mice with mucormycosis. Inhibition of the toxin in Rhizopus delemar through RNA interference compromises the ability of the fungus to damage host cells and attenuates virulence in mice. This 17 kDa toxin has structural and functional features of the plant toxin ricin, including the ability to inhibit protein synthesis through its N-glycosylase activity, the existence of a motif that mediates vascular leak and a lectin sequence. Antibodies against the toxin inhibit R. delemar- or toxin-mediated vascular permeability in vitro and cross react with ricin. A monoclonal anti-ricin B chain antibody binds to the toxin and also inhibits its ability to cause vascular permeability. Therefore, we propose the name 'mucoricin' for this toxin. Not only is mucoricin important in the pathogenesis of mucormycosis but our data suggest that a ricin-like toxin is produced by organisms beyond the plant and bacterial kingdoms. Importantly, mucoricin should be a promising therapeutic target.

Comparative immunopathogenesis in a murine model of inhalative infection with the mucormycetes Lichtheimia corymbifera and Rhizopus arrhizus.

Pathogenic mucormycetes induce diseases with considerable morbidity and mortality in immunocompromised patients. Virulence data comparing different Mucorales species and various underlying risk factors are limited. We therefore compared the pathogenesis of inhalative infection by Rhizopus (R.) arrhizus and Lichtheimia (L.) corymbifera in murine models for predominant risk factors for onset of infection. Mice with diabetes or treated with cyclophosphamide or cortisone acetate were challenged via the intranasal route with an isolate of R. arrhizus or L. corymbifera, respectively. Clinical, immunological and inflammation parameters as well as efficacy of posaconazole prophylaxis were monitored over 14 days. Whereas immunocompetent mice showed no clinical symptoms after mucormycete infection, mice treated with either cyclophosphamide (CP) or cortisone acetate (CA) were highly susceptible. Animals infected with the isolate of R. arrhizus showed prolonged survival and lower mortality, compared to those exposed to the L. corymbifera isolate. This lower virulence of R. arrhizus was risk factor-dependent, since diabetic mice died only after infection with Rhizopus, whereas all Lichtheimia-infected diabetic animals survived. Under posaconazole prophylaxis, both mucormycetes were able to establish breakthrough infections in CA- and CP-treated mice, but the course of infection was significantly delayed. Detailed analysis revealed that susceptibility of CA- and CP-treated mice could not be mimicked by exclusive lack or downmodulation of neutrophils, platelets or complement, but can be supposed to be the consequence of a broad immunosuppressive effect induced by the drugs. Both Lichtheimia corymbifera and Rhizopus arrhizus induce invasive mycoses in immunocompromised hosts after inhalative infection. Key parameters such as virulence and immunopathogenesis vary strongly according to fungal species and underlying risk group. Selected neutropenia is no sufficient risk factor for onset of inhalative mucormycosis.

Pharmacokinetics of Intravenous Isavuconazole in Solid-Organ Transplant Recipients.

Isavuconazole may be useful in treating and preventing fungal infections in solid-organ transplant (SOT) recipients due to its safety profile and activity against Aspergillus and some Mucorales Isavuconazole has favorable pharmacokinetics based on clinical trials in various patient populations, but data are limited in SOT recipients. We evaluated the steady-state pharmacokinetics of isavuconazole in 26 SOT recipients receiving the drug intravenously for prophylaxis. There was moderate interpatient variability in isavuconazole pharmacokinetic parameters (coefficients of variation of 51% for the area under the plasma concentration-versus-time curve [AUC] and 59% for the trough plasma concentration [Ctrough]). AUC and steady-state Ctrough were significantly lower in women, patients with a body mass index of ≥18.5 kg/m2, and those receiving hemodialysis. Trough plasma concentrations were highly correlated with AUCs (R2 = 0.94) and can serve as a suitable measure of isavuconazole exposure in patients. In conclusion, moderate interpatient variability in isavuconazole exposure, the identification of factors associated with lower exposure, the recognition that Ctrough is a surrogate marker for AUC, and the availability of a simple analytical method suggest that therapeutic drug monitoring (TDM) may be useful for guiding treatment in at least some SOT recipients. Future studies are needed to correlate isavuconazole exposure with patients' clinical outcomes and to determine the clinical role of TDM.

Inhibition of EGFR Signaling Protects from Mucormycosis.

Mucormycosis is a life-threatening, invasive fungal infection that is caused by various species belonging to the order Mucorales. Rhizopus species are the most common cause of the disease, responsible for approximately 70% of all cases of mucormycosis. During pulmonary mucormycosis, inhaled Rhizopus spores must adhere to and invade airway epithelial cells in order to establish infection. The molecular mechanisms that govern this interaction are poorly understood. We performed an unbiased survey of the host transcriptional response during early stages of Rhizopus arrhizus var. delemar (R. delemar) infection in a murine model of pulmonary mucormycosis using transcriptome sequencing (RNA-seq). Network analysis revealed activation of the host's epidermal growth factor receptor (EGFR) signaling. Consistent with the RNA-seq results, EGFR became phosphorylated upon in vitro infection of human alveolar epithelial cells with several members of the Mucorales, and this phosphorylated, activated form of EGFR colocalized with R. delemar spores. Inhibition of EGFR signaling with cetuximab or gefitinib, specific FDA-approved inhibitors of EGFR, significantly reduced the ability of R. delemar to invade and damage airway epithelial cells. Furthermore, gefitinib treatment significantly prolonged survival of mice with pulmonary mucormycosis, reduced tissue fungal burden, and attenuated the activation of EGFR in response to pulmonary mucormycosis. These results indicate EGFR represents a novel host target to block invasion of alveolar epithelial cells by R. delemar, and inhibition of EGFR signaling provides a novel approach for treating mucormycosis by repurposing an FDA-approved drug.IMPORTANCE Mucormycosis is an increasingly common, highly lethal fungal infection with very limited treatment options. Using a combination of in vivo animal models, transcriptomics, cell biology, and pharmacological approaches, we have demonstrated that Mucorales fungi activate EGFR signaling to induce fungal uptake into airway epithelial cells. Inhibition of EGFR signaling with existing FDA-approved drugs significantly increased survival following R. arrhizus var. delemar infection in mice. This study enhances our understanding of how Mucorales fungi invade host cells during the establishment of pulmonary mucormycosis and provides a proof-of-concept for the repurposing of FDA-approved drugs that target EGFR function.

Osteomielitis por mucorales (OMM) asociada a artroscopia de reparación de ligamento cruzado anterior: investigación epidemiológica y recomendaciones para su prevención / Mucor osteomyelitis after arthroscopic repair of ACL. Epidemiological investigation

OBJETIVO: Describir la investigación epidemiológica de osteomielitis por Mucorales (OMM) post reparación artroscópica de LCA (RA-LCA) en Argentina. MATERIAL Y MÉTODO: 1) Revisión de los casos; 2) Relevamiento de 3 instituciones; 3) Cultivo micológico de materiales quirúrgicos; 4) Encuesta a instrumentadoras; 5) Secuenciación de las cepas de Rhizopus y 6) Redacción de recomendaciones. RESULTADOS: Del 2005 al 2017 se identificaron 40 casos de OMM (Rhizopus sp.) post reparación artroscópica de LCA en pacientes inmunocompetentes de 12 jurisdicciones de Argentina. El diagnóstico fue por cultivo (22/31), y por anatomía patológica (9). La edad promedio fue 29 años. El 84% de 38 casos eran varones. Intervinieron 13 ortopedias. El implante fue importado en 8/20 casos y nacional en 12. En las 3 instituciones se observó: manejo inadecuado del aire de quirófano, variabilidad en la limpieza del artroscopio, en el taladro utilizado, y en el manejo de materiales que llegan de las ortopedias y falta de trazabilidad de los implantes. Los cultivos micológicos de los materiales fueron negativos. La encuesta a instrumentadores confirmó los hallazgos de los relevamientos. La secuenciación de las cepas de Rhizopus demostró predominio de policlonalidad. CONCLUSIÓN: La OMM es una complicación posible luego de la RA-LCA en instituciones privadas de Argentina. No se identificó un origen único. Se detectaron múltiples prácticas que favorecen la contaminación de la cirugía con hongos filamentosos (manejo del aire de quirófano, del artroscopio, de los materiales provenientes de ortopedia, etc.). En base a estos hallazgos la Asociación Argentina de Artroscopía sugiere medidas de prevención. Implicancia clínica: Prevención de osteomielitis por Mucorales post- cirugía artroscópica para ligamento cruzado anterior. Tipo de estudio: Serie de casos. Nivel de Evidencia: IV.

OBJECTIVE: To describe the epidemiological investigation of Mucor osteomyelitis (MO) after arthroscopic repair of ACL (ARACL) in Argentina. MATERIAL Y METHODS: 1) Review of cases; 2) Survey of 3 institutions; 3) Mycological culture of surgical materials; 4) Survey of instrumentists; 5) Sequencing of Rhizopus strains and 6) Writing of recommendations. RESULTS: From 2005 to 2017, 40 cases of MO (Rhizopus sp.) Post AR-ACL were identified in immunocompetent patients from 12 jurisdictions of Argentina. The diagnosis was made by culture (22/31), and by pathology (9). The average age was 29 years. 84% of 38 cases were male. Thirteen orthopedics intervened. The implant was imported in 8/20 cases and national in 12. In the 3 institutions it was observed: inadequate handling of the operating room air, variability in the cleaning of the arthroscope, in the drill used, and in the handling of materials that come from the orthopedics and lack of traceability of the implants. The mycological cultures of the materials were negative. The survey of instrumentists confirmed the findings of the surveys. The sequencing of Rhizopus strains showed a predominance of polyclonality. CONCLUSION: MO is a possible complication after AR-ACL in private institutions in Argentina. A unique origin was not identified. Multiple practices that favor the contamination of surgery with filamentous fungi (handling of operating room air, arthroscope, materials from orthopedics, etc.) were detected. Based on these findings, the Argentine Association of Arthroscopy suggests prevention measures. Clinical relevance: Prevention of Mucor osteomyelitis after arthroscopic surgery for anterior cruciate ligament. Type study: Cases series. Level of evidence: IV.

Prophylaxis with Isavuconazole or Posaconazole Protects Immunosuppressed Mice from Pulmonary Mucormycosis.

We assessed prophylactic or continuous therapy of isavuconazole, posaconazole, or voriconazole in treating pulmonary murine mucormycosis. In the prophylaxis studies, only isavuconazole treatment resulted in significantly improved survival and lowered tissue fungal burden of immunosuppressed mice infected with Rhizopus delemar. In the continuous treatment studies, isavuconazole and posaconazole, but not voriconazole, equally prolonged survival time and lowered tissue fungal burden compared to placebo-treated mice. These results support the use of isavuconazole and posaconazole in prophylaxis treatment.