Development of a Combat-Relevant Murine Model of Wound Mucormycosis: A Platform for the Pre-Clinical Investigation of Novel Therapeutics for Wound-Invasive Fungal Diseases

Wound-invasive fungal diseases (WIFDs), especially mucormycosis, have emerged as life-threatening infections during recent military combat operations. Many combat-relevant fungal pathogens are refractory to current antifungal therapy. Therefore, animal models of WIFDs are urgently needed to investigate new therapeutic solutions. Our study establishes combat-relevant murine models of wound mucormycosis using Rhizopus arrhizus and Lichtheimia corymbifera, two Mucorales species that cause wound mucormycosis worldwide. These models recapitulate the characteristics of combat-related wounds from explosions, including blast overpressure exposure, full-thickness skin injury, fascial damage, and muscle crush. The independent inoculation of both pathogens caused sustained infections and enlarged wounds. Histopathological analysis confirmed the presence of necrosis and fungal hyphae in the wound bed and adjacent muscle tissue. Semi-quantification of fungal burden by colony-forming units corroborated the infection. Treatment with liposomal amphotericin B, 30 mg/kg, effectively controlled R. arrhizus growth and significantly reduced residual fungal burden in infected wounds (p < 0.001). This study establishes the first combat-relevant murine model of wound mucormycosis, paving the way for developing and evaluating novel antifungal therapies against combat-associated WIFDs.

Facial and systemic mucormycosis caused by Lichtheimia corymbifera in a goat: case report and literature review of fungal infections in goats

An 8-y-old Pygora doe was presented to the University of California-Davis, Veterinary Medical Teaching Hospital because of non-healing facial swelling of 2-wk duration. The lesion grew despite medical treatment, causing discomfort masticating, little-to-no airflow from the right nasal passage, and led to euthanasia. On gross examination, a large facial mass with a draining tract through the skin and hard palate was identified. On section, the mass was brown-pink, homogeneous, and friable. Abscess-like masses were identified in the lungs and kidney. Histopathology of the face, including oral and nasal cavities, salivary glands, and lymph nodes, as well as the lung and kidney lesions, revealed large areas of necrosis with numerous wide ribbon-like, mostly aseptate, fungal hyphae consistent with zygomycetes. PCR for fungal organisms performed on formalin-fixed, paraffin-embedded tissue from the face identified Lichtheimia corymbifera (formerly Absidia corymbifera) of the order Mucorales and an Aspergillus sp. The lesion was suspected to have started either as a fungal rhinitis or dental feed impaction, subsequently spreading to the face and systemically to the lungs and kidney. We describe here the lesions associated with facial mucormycosis in a goat and present a literature review of L. corymbifera infection in veterinary species and fungal infections in goats.

Hyphae of Rhizopus arrhizus and Lichtheimia corymbifera Are More Virulent and Resistant to Antifungal Agents Than Sporangiospores In Vitro and in Galleria mellonella

Mucorales species cause debilitating, life-threatening sinopulmonary diseases in immunocompromised patients and penetrating wounds in trauma victims. Common antifungal agents against mucormycosis have significant toxicity and are often ineffective. To evaluate treatments against mucormycosis, sporangiospores are typically used for in vitro assays and in pre-clinical animal models of pulmonary infections. However, in clinical cases of wound mucormycosis caused by traumatic inoculation, hyphal elements found in soil are likely the form of the inoculated organism. In this study, Galleria mellonella larvae were infected with either sporangiospores or hyphae of Rhizopus arrhizus and Lichtheimia corymbifera. Hyphal infections resulted in greater and more rapid larval lethality than sporangiospores, with an approximate 10-16-fold decrease in LD50 of hyphae for R. arrhizus (p = 0.03) and L. corymbifera (p = 0.001). Liposomal amphotericin B, 10 mg/kg, was ineffective against hyphal infection, while the same dosage was effective against infections produced by sporangiospores. Furthermore, in vitro, antifungal susceptibility studies show that minimum inhibitory concentrations of several antifungal agents against hyphae were higher when compared to those of sporangiospores. These findings support using hyphal elements of Mucorales species for virulence testing and antifungal drug screening in vitro and in G. mellonella for studies of wound mucormycosis.

Scedosporium apiospermum and Lichtheimia corymbifera Co-Infection Due to Inhalation of Biogas in Immunocompetent Patients: A Case Series

This is the first report describing co-infection of Scedosporium apiospermum and Lichtheimia corymbifera caused by biogas inhalation in two people without underlying medical conditions. Two patients fell into the same pig manure pit at the same time while rescuing another patient (this person died in a few hours) and inhaled biogas. Both patients were diagnosed with pulmonary fungal disease and developed acute liver failure around Day 52. Their results were negative for the 1,3-β-d-glucan test and weakly positive for the galactomannan test. They were treated with amphotericin B and/or posaconazole without surgery. The patient in case 2 required amphotericin B deoxycholate aerosol inhalation to complete the treatment. Both patients recovered completely. For patients with mucormycosis confined to the lungs who cannot tolerate intravenous drip amphotericin B, increasing the dose of nebulised administration maybe a salvage regimen.

A Rare Fungal Orbital Infection in an Immunocompetent Young Male Caused by Lichtheimia corymbifera (Absidia corymbifera)

AIM

To present a case of orbital fungal infection caused by a rare fungus, Lichtheimia corymbifera (Absidia corymbifera) in an immunocompetent individual.

MATERIALS AND METHODS

A retrospective case study.

RESULT

A 23-year-old male presented with painful proptosis of the right eye for 3 months. Examination revealed normal vision and pupillary light reflex but restricted ocular movements in the right eye. A tender, firm mass was palpable along the inferomedial quadrant of the right orbit. He had acute worsening of proptosis with loss of light perception within 24 hours. Magnetic resonance imaging (MRI) showed a heterogeneously enhancing lesion in the right orbit. Urgent incisional biopsy revealed the growth of Absidial fungal infection. He received intravenous Amphotericin B for 2 weeks with no response. Repeat MRI revealed an extension of the infection up to the cavernous sinus and intracranial optic nerve. He was managed by subtotal exenteration, socket irrigation with Amphotericin B, and intravenous Amphotericin B.

CONCLUSION

Invasive orbital fungal infection, though rare, should be considered a differential diagnosis in immunocompetent patients with fulminant proptosis and vision loss.

Corticosteroids alter alveolar macrophage control of Lichtheimia corymbifera spores in an ex vivo mouse model

Alveolar macrophages (AM) are the first-line lung defense against Mucorales in pulmonary mucormycosis. Since corticosteroid use is a known risk factor for mucormycosis, the aim of this study was to describe the role of corticosteroids on AM capacities to control Lichtheimia corymbifera spore growth using a new ex vivo model. An in vivo mouse model was developed to determine the acetate cortisone dose able to trigger pulmonary invasive infection. Then, in the ex vivo model, male BALB/c mice were pretreated with the corticosteroid regimen triggering invasive infection, before AM collection through bronchoalveolar lavage. AMs from corticosteroid-treated mice and untreated control AMs were then exposed to L. corymbifera spores in vitro (ratio 1:5). AM control of fungal growth, adherence/phagocytosis, and oxidative burst were assessed using optical densities by spectrophotometer, flow cytometry, and 2', 7'-dichlorofluoresceine diacetate fluorescence, respectively. Cortisone acetate at 500 mg/kg, at D-3 and at D0, led to pulmonary invasive infection at D3. Co-incubated spores and AMs from corticosteroid-treated mice had significantly higher absorbance (fungal growth) than co-incubated spores and control AMs, at 24 h (P = .025), 36 h (P = .004), and 48 h (P = .001). Colocalization of spores with AMs from corticosteroid-treated mice was significantly lower than for control AMs (7.6 ± 1.9% vs 22.3 ± 5.8%; P = .003), reflecting spore adherence and phagocytosis inhibition. Finally, oxidative burst was significantly increased when control AMs were incubated with spores (P = 0.029), while corticosteroids hampered oxidative burst from treated AMs (P = 0.321). Corticosteroids enhanced fungal growth of L. corymbifera through AM phagocytosis inhibition and burst oxidative decrease in our ex vivo model.

LAY SUMMARY

The aim of this study was to describe the impact of corticosteroids on alveolar macrophage (AM) capacities to control Mucorales growth in a new murine ex vivo model. Corticosteroids enhanced fungal growth of L. corymbifera through AM phagocytosis inhibition and burst oxidative decrease.

[Uncommon mycoses]

BACKGROUND

Fungal infections should be suspected in severe wounds that have been contaminated with organic material or soil, even when the patient is immunocompetent. The aim of this article is to contribute to a better understanding and knowledge of the antifungal sensitivity and epidemiology of some rare pathogens that may trigger severe infections.

CASE REPORT

Four different moulds were isolated from the wounds of an immunocompetent woman who was involved in a road accident: Lichtheimia corymbifera, Scedosporium boydii, Fusarium solani and Purpureocillium lilacinum. Some of them were isolated from different sites. A profile of in vitro resistance was performed with an Epsilometer (Etest™) using five antifungal agents: voriconazole, posaconazole, itraconazole, anidulafungin an amphotericin B. The results obtained were consistent with those from other cases reported in the literature.

CONCLUSIONS

Early aggressive surgery, antifungal therapy and, above all, frequent debridement of necrotic tissue, are the tools against filamentous fungi infections. Antifungal sensitivity of any mould involved in an infection has to be determined, in order to a better understanding of these rare pathogens whose incidence is increasing.

Local extensive granulomatous inflammation of the neck region and lymphangitis caused by Lichtheimia corymbifera infection in a Japanese Black calf

A 7-month-old female Japanese Black calf developed elongated, nodular mass measuring 30 × 16 cm extended from the retropharyngeal region to mid lateral neck region. Histological examination revealed granulomatous lymphangitis with non-septate fungal hyphae recognized throughout the lesions. Fungal culture, DNA sequencing and molecular phylogenetic tree analysis confirmed the sequence of Lichtheimia corymbifera. The lymphogenous route was speculated to be the main route of fungal spread leading to the characteristic nodular appearance of this case.

Coinfection with Lichtheimia corymbifera and Aspergillus flavus in an Immune-Competent Patient Mimicking as Pulmonary-Renal Syndrome

Lichtheimia corymbifera and Aspergillus flavus pulmonary coinfection has been rarely reported in immune-competent patients. We report case of a young male who presented with clinical features of pulmonary-renal syndrome and was later diagnosed to have bilateral polymicrobial fungal lung infection.

Early Diagnosis of Cutaneous Mucormycosis Due to Lichtheimia corymbifera After a Traffic Accident

A case report of cutaneous mucormycosis and obstacles to early diagnosis is presented. A 38-year-old male was involved in a car accident that led to amputation of both lower limbs. Subsequently, he developed fungal wound infection of the left lower limb stump. The infection was detected very early, although the diagnosis was difficult because only a small area was affected and histopathological examination was initially negative. The infection was proven by microscopy, culture and histopathology. The isolate was identified by sequencing of the rDNA ITS region gene (internal transcribed spacer region of ribosomal DNA) as Lichtheimia corymbifera. Liposomal amphotericin B and surgery were successful in management of the disease.

Mucormycosis in haematological patients: case report and results of prospective study in Saint Petersburg, Russia

We prospectively observed 36 haematological patients with mucormycosis from nine hospitals of St. Petersburg during 2004-2013. The most frequent underlying diseases were acute leukaemia (64%), and main risk factors were prolonged neutropenia (92%) and lymphocytopenia (86%). In 50% of the patients, mucormycosis was diagnosed 1-65 days after invasive aspergillosis. Main clinical form of mucormycosis was pulmonary (64%), while two or more organ involvement was noted in 50% of the cases. The most frequent aetiological agents of mucormycosis were Rhizopus spp. (48%). Twelve-week survival rate was 50%. Combination therapy (echinocandins + amphotericin B forms) and recovery from the underlying disease significantly improved the survival rate.