Chromoblastomycosis: an etiological, epidemiological, clinical, diagnostic, and treatment update

Case Report: Treatment of Chromoblastomycosis with Combinations including Acitretin: A Report of Two Cases

Chromoblastomycosis is a cutaneous fungal infection caused by dematiaceous fungi that belong to the order Chaetothyriales and family Herpotrichiellaceae. This infection is prevalent in tropical and subtropical areas and has been designated as a neglected tropical disease according to the WHO. Chromoblastomycosis infection is difficult to treat, and there are limited therapeutic options, making urgent the characterization of new medicines or approaches to treat such infection. In the present case report, two patients with extensive chromoblastomycosis lesions were treated with the combination of itraconazole, acitretin, and imiquimod. In the fourth month of treatment, both patients showed improvement of verrucous plates, suggesting that acitretin combined with drugs already used in chromoblastomycosis therapy can decrease the time of treatment, improving patient's quality of life.

Fonsecaeapedrosoi Conidia and Hyphae Activate Neutrophils Distinctly: Requirement of TLR-2 and TLR-4 in Neutrophil Effector Functions

Chromoblastomycosis is a chronic and progressive subcutaneous mycosis caused mainly by the fungus Fonsecaea pedrosoi. The infection is characterized by erythematous papules and histological sections demonstrating an external layer of fibrous tissue and an internal layer of thick granulomatous inflammatory tissue containing mainly macrophages and neutrophils. Several groups are studying the roles of the innate and adaptive immune systems in F. pedrosoi infection; however, few studies have focused on the role of neutrophils in this infection. In the current study, we verify the importance of murine neutrophils in the killing of F. pedrosoi conidia and hyphae. We demonstrate that phagocytosis and reactive oxygen species during infection with conidia are TLR-2- and TLR-4-dependent and are essential for conidial killing. Meanwhile, hyphal killing occurs by NET formation in a TLR-2-, TLR-4-, and ROS-independent manner. In vivo experiments show that TLR-2 and TLR-4 are also important in chromoblastomycosis infection. TLR-2KO and TLR-4KO animals had lower levels of CCL3 and CXCL1 chemokines and impaired neutrophil migration to the infected site. These animals also had higher fungal loads during infection with F. pedrosoi conidia, confirming that TLR-2 and TLR-4 are essential receptors for F. pedrosoi recognition and immune system activation. Therefore, this study demonstrates for the first time that neutrophil activation during F. pedrosoi is conidial or hyphal-specific with TLR-2 and TLR-4 being essential during conidial infection but unnecessary for hyphal killing by neutrophils.

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.

Early immune response against Fonsecaea pedrosoi requires Dectin-2-mediated Th17 activity, whereas Th1 response, aided by Treg cells, is crucial for fungal clearance in later stage of experimental chromoblastomycosis

Chromoblastomycosis (CBM) is a chronic worldwide subcutaneous mycosis, caused by several dimorphic, pigmented dematiaceous fungi. It is difficult to treat patients with the disease, mainly because of its recalcitrant nature. The correct activation of host immune response is critical to avoid fungal persistence in the tissue and disease chronification. CD4+ T cells are crucial for the development of protective immunity to F. pedrosoi infection. Here, we investigated T helper cell response dynamics during experimental CBM. Following footpad injection with F. pedrosoi hyphae and conidia, T cells were skewed towards a Th17 and Th1 phenotype. The Th17 population was the main Th cell subset found in the infected area during the early stages of experimental murine CBM, followed by Th1 predominance in the later stages, coinciding with the remission phase of the disease in this experimental model. Depletion of CD25+ cells, which leads to a reduction of Treg cells in the draining lymph node, resulted in decline in fungal burden after 14 days of infection. However, fungal cells were not cleared in the later stages of the disease, prolonging CBM clinical features in those animals. IL-17A and IFN-γ neutralization hindered fungal cell elimination in the course of the disease. Similarly, in dectin-2 KO animals, Th17 contraction in the course of experimental CBM was accompanied by fungal burden decrease in the first 14 days of infection, although it did not affect disease resolution. In this study, we gained insight into T helper subsets' dynamics following footpad injections of F. pedrosoi propagules and uncovered their contribution to disease resolution. The Th17 population proved to be important in eliminating fungal cells in the early stages of infection. The Th1 population, in turn, closely assisted by Treg cells, proved to be relevant not only in the elimination of fungal cells at the beginning of infection but also essential for their complete elimination in later stages of the disease in a mouse experimental model of CBM.

Case for diagnosis. Pruritic erythematosquamous lesion in the auricle

Chromoblastomycosis is a subcutaneous mycosis with chronic evolution that mainly affects the lower limbs and, less frequently, the auricles. Clinically, it presents with papillary verrucous, nodular, and/or tumoral lesions, whether isolated or infiltrated, forming plaques and, sometimes, atrophic in some areas. Histopathologically, it is characterized by a dermal granulomatous inflammatory infiltrate, and the diagnosis can be confirmed by the presence of fumagoid bodies in anatomopathological or direct mycological exams. The treatment to be indicated will depend on the extent and location of the lesions, using systemic antifungals, surgical removal, cryotherapy, thermotherapy, and immunoadjuvants. The present study reports an atypical presentation of chromoblastomycosis on the auricle.

A case of mycetoma-like chromoblastomycosis in Qatar

Chromoblastomycosis is one of the neglected tropical mycoses associated with chronic infection of the skin and subcutaneous tissues. We report a case of 49-year-old patient originally from India presented with a mycetoma-like lesion in his right foot which was slowly progressing over three-year period. The diagnosis of chromoblastomycosis was confirmed following surgical excision and identification of the unique histological pathology of muriform bodies. The patient was subsequently treated with a prolonged course of oral itraconazole with a favorable outcome. The clinical presentations, assessment and management of the disease are outlined.

A screening of the MMV Pathogen Box® reveals new potential antifungal drugs against the etiologic agents of chromoblastomycosis

Chromoblastomycosis (CBM) is a chronic subcutaneous mycosis caused by traumatic implantation of many species of black fungi. Due to the refractoriness of some cases and common recurrence of CBM, a more effective and less time-consuming treatment is mandatory. The aim of this study was to identify compounds with in vitro antifungal activity in the Pathogen Box® compound collection against different CBM agents. Synergism of these compounds with drugs currently used to treat CBM was also assessed. An initial screening of the drugs present in this collection at 1 μM was performed with a Fonsecaea pedrosoi clinical strain according to the EUCAST protocol. The compounds with activity against this fungus were also tested against other seven etiologic agents of CBM (Cladophialophora carrionii, Phialophora verrucosa, Exophiala jeanselmei, Exophiala dermatitidis, Fonsecaea monophora, Fonsecaea nubica, and Rhinocladiella similis) at concentrations ranging from 0.039 to 10 μM. The analysis of potential synergism of these compounds with itraconazole and terbinafine was performed by the checkerboard method. Eight compounds inhibited more than 60% of the F. pedrosoi growth: difenoconazole, bitertanol, iodoquinol, azoxystrobin, MMV688179, MMV021013, trifloxystrobin, and auranofin. Iodoquinol produced the lowest MIC values (1.25-2.5 μM) and MMV688179 showed MICs that were higher than all compounds tested (5 - >10 μM). When auranofin and itraconazole were tested in combination, a synergistic interaction (FICI = 0.37) was observed against the C. carrionii isolate. Toxicity analysis revealed that MMV021013 showed high selectivity indices (SI ≥ 10) against the fungi tested. In summary, auranofin, iodoquinol, and MMV021013 were identified as promising compounds to be tested in CBM models of infection.

[Management of chromoblastomycosis, a challenge for limited-resource countries such as Madagascar]

INTRODUCTION

Chromoblastomycosis (CBM) is a chronic fungal infection of the skin and subcutaneous tissue caused by dematiaceous fungi. CBM lesions are recalcitrant and extremely difficult to eradicate. We report three cases of CBM with difficulties in therapeutic management.

OBSERVATION

Three men aged 36, 50 and 67 years, all farmers, presented for between three and ten years with hyperkeratotic, scaly plaques with black dots on the right thigh and left leg, respectively. For all patients, mycological examination showed fumagoid cells, all of which were pathognomonic for CBM. PCR identified Fonsecaeanubica in one patient and Cladophialophoracarrionii in two patients. All patients received itraconazole 200mg/day for over 18 months. Two patients required combined therapy with terbinafine for seven months, which improved lesions; however, relapse occurred in one patient during the 5th month of this combined therapy and five months after the end of this treatment in the other. The patient on monotherapy (itraconazole) also presented recurrence of lesions five months after the end of treatment.

DISCUSSION

Itraconazole is the standard therapy for CBM, with cure rates ranging from 15 to 80%. Success with itraconazole after eight to twelve months was reported by several authors. Fonsecaea and Cladophialophora are the most common species found in Madagascar, and while these organisms are susceptible to triazoles in vitro, clinical response is not so clear-cut.

CONCLUSION

Although unavailable in Madagascar, posaconazole and isavoconazole appear to be effective in treating chromoblastomycosis.

Photodynamic therapy combined with antifungal drugs against chromoblastomycosis and the effect of ALA-PDT on Fonsecaea in vitro

Background

Chromoblastomycosis is a chronic skin and subcutaneous fungal infection caused by dematiaceous fungi and is associated with low cure and high relapse rates. In southern China, Fonsecaea monophora and Fonsecaea pedrosoi are the main causative agents.

Principal findings

We treated 5 refractory and complex cases of chromoblastomycosis with 5-aminolevulinic acid photodynamic therapy (ALA-PDT) combined with oral antifungal drugs. The lesions improved after 4 to 9 sessions of ALA-PDT treatment at an interval of one or two weeks, and in some cases, mycological testing results became negative. The isolates were assayed for susceptibility to antifungal drugs and ALA-PDT in vitro, revealing sensitivity to terbinafine, itraconazole and voriconazole, with ALA-PDT altering the cell wall and increasing reactive oxygen species production.

Conclusions

These results provide the basis for the development of a new therapeutic approach, and ALA-PDT combined with oral antifungal drugs constitutes a promising alternative method for the treatment of refractory and complex cases of chromoblastomycosis.

Chromoblastomycosis, a neglected tropical disease, is one of the most frequently encountered subcutaneous mycoses. The disease is usually caused by traumatic inoculation of a specific group of dematiaceous fungi. Chromoblastomycosisis characterized by slowly expanding skin lesions and is associated with low cure and high relapse rates. In recent years, effective methods, such as photodynamic therapy (PDT), have been employed for inhibiting the pathogen’s activity. The authors treated 5 refractory and complex cases of chromoblastomycosis with 5-aminolevulinic acid photodynamic therapy (ALA-PDT) combined with oral antifungal drugs. The lesions improved after 4 to 9 sessions of ALA-PDT treatment at an interval of one or two weeks, and in some cases, mycological testing results became negative. The authors also found that ALA-PDT alter the fungi cell wall and increase reactive oxygen species production. This research provides the basis for the development of a new therapeutic approach, and ALA-PDT combined with oral antifungal drugs constitutes a promising alternative method for the treatment of refractory and complex cases of chromoblastomycosis.

Synergistic effect of terbinafine and amphotericin B in killing Fonsecaea nubica in vitro and in vivo

Chromoblastomycosis is a chronic fungal infection. Itraconazole and terbinafine are the most recommended antifungal drugs for chromoblastomycosis, while amphotericin B is not usually recommended. A patient with chromoblastomycosis in our hospital showed poor clinical responses to itraconazole and terbinafine. The fungus isolated from the lesions of this patient was identified as Fonsecaea nubica and numbered zssy0803. In vitro antifungal susceptibilities of F. nubica zssy0803 to terbinafine, amphotericin B, itraconazole, voriconazole and caspofungin were evaluated, as well as the combinations of terbinafine with the other four antifungals. The combined effect of terbinafine and amphotericin B on other 20 clinical F. nubica strains was also evaluated. The minimal inhibitory concentrations of terbinafine, amphotericin B, itraconazole, voriconazole and caspofungin on F. nubica zssy0803 were 0.25 μg/mL, 2 μg/mL, 1 μg/mL, 4 μg/mL and 8 μg/mL, respectively. The combination of terbinafine and amphotericin B showed the lowest fractional inhibitory concentration index of 0.28 to F. nubica zssy0803 in comparison with combinations of terbinafine and the other four antifungal drugs. The combination of terbinafine and amphotericin B was also synergistic for all the other 20 F. nubica strains. Then, the combination of oral terbinafine (500 mg/day) and intralesional injections of amphotericin B (1 mg/mL) was used to treat this patient. After this combined therapy for 25 weeks and terbinafine monotherapy for additional 12 weeks, the patient was cured. These findings indicate for the first time that terbinafine and amphotericin B are synergistic in killing F. nubica both in vitro and in vivo.

Endemic Mycoses in Children

The endemic mycoses are a group of infections caused by fungi with a distinct geographic distribution, defined by climatic and environmental conditions. The systemic endemic mycoses, namely histoplasmosis, blastomycosis, talaromycosis, coccidioidomycosis and paracoccidioidomycosis, occur after the inhalation of fungal spores. The cutaneous endemic mycoses, including sporotrichosis, mycetoma, entomophthoramycosis and chromoblastomycosis, enter the host via traumatic inoculation of the skin. Clinical presentation varies between these relatively heterogeneous infections, as does the susceptibility of immunosuppressed patients to disease. An understanding of the geographic range, typical manifestations, diagnostic methods, and treatment of the endemic mycoses is key in assessing patients presenting with atypical infections who may have traveled to endemic areas.