[From treatment to whole course management: envisioning comprehensive management of Talaromycosis marneffei]

Talaromycosis marneffei has been increasing in recent years. Our understanding of this disease has gradually deepened through extensive basic and clinical research, but there are still many limitations. In this article, by incorporating the latest research advancements, we discuss important issues in managing Talaromycosis marneffei trends, aiming to guide effective prevention and control of the disease, improving public health, and reducing the healthcare burden.

Apophysomyces variabilis as an emerging pathogen in Mainland China

BACKGROUND

Mucormycosis is a rare form of invasive, rapidly progressive and lethal opportunistic fungal infection caused by Mucorales. Although Rhizopus arrhizus (R. arrhizus) is the most commonly isolated Mucorales worldwide, infections caused by Apophysomyces variabilis (A. variabilis) are increasing.

OBJECTIVES AND METHODS

We present a case of necrotizing fasciitis caused by A. variabilis in an immunocompetent woman. In order to further understand the characteristics of the strain isolated from the patient, we identified the strain through ITS sequencing, assessed the ability to tolerate salt concentrations and temperature conditions, in addition to performing in vitro drug susceptibility testing against common antifungal agents.

RESULTS

The strain showed 98.76% identity with A. variabilis in the NCBI database, and it was found to tolerate higher temperatures and salt concentrations than previously reported strains. The strain was sensitive to amphotericin B and posaconazole, but not to voriconazole, itraconazole, 5-fluorocytosine and echinocandins.

CONCLUSIONS

This case indicates that Mucorales caused by A. variabilis should be recognised as an emerging pathogen that can cause a high mortality rate in the absence of prompt diagnosis and proper treatment in China, aggressive surgical debridement combined with prompt and appropriate antifungal treatment may improve outcomes.

In vitro Antifungal Susceptibility Profiles of Cryptococcus neoformans var. grubii and Cryptococcus gattii Clinical Isolates in Guangxi, Southern China

This study analyzed the in vitro drug sensitivity of Cryptococcus spp. from Guangxi, Southern China. One hundred three strains of Cryptococcus were recovered from 86 patients; 14 were HIV positive and 72 were HIV negative. Ninety-two strains were identified as Cryptococcus neoformans var. grubii, while 11 strains were identified as Cryptococcus gattii (5 C. gattii sensu stricto and 6 Cryptococcus deuterogattii). The recovered strains were tested against commonly used antifungal drugs (fluconazole, amphotericin B, 5-fluorocytosine, itraconazole, and voriconazole) and to novel antifungal drugs (posaconazole and isavuconazole) using CLSI M27-A4 method. The results showed that all isolates were susceptible to most antifungal drugs, of which the minimum inhibitory concentration (MIC) ranges were as follows: 0.05-4 μg/ml for fluconazole, 0.25-1 μg/ml for amphotericin B; 0.0625-2 μg/ml for 5-fluorocytosine, 0.0625-0.25 μg/ml for itraconazole, 0.0078-0.25 μg/ml for voriconazole, 0.0313-0.5 μg/ml for posaconazole, 0.0020-0.125 μg/ml for isavuconazole for C. neoformans var. grubii isolates, and 1-16 μg/ml for fluconazole, 0.125-1 μg/ml for 5-fluorocytosine, 0.25-1 μg/ml for amphotericin B, 0.0625-0.25 μg/ml for itraconazole, 0.0156-0.125 μg/ml for voriconazole, 0.0156-0.25 μg/ml for posaconazole, and 0.0078-0.125 μg/ml for isavuconazole for C. gattii isolates. Furthermore, some C. neoformans var. grubii isolates were found to be susceptible-dose dependent to 5-fluorocytosine and itraconazole. In addition, a reduction in the potency of fluconazole against C. gattii is possible. We observed no statistical differences in susceptibility of C. neoformans var. grubii and C. gattii in the tested strains. Continuous observation of antifungal susceptibility of Cryptococcus isolates is recommended to monitor the emergence of resistant strains.

Anti-IFN-γ autoantibodies underlie disseminated Talaromyces marneffei infections

Talaromyces marneffei causes life-threatening opportunistic infections, mainly in Southeast Asia and South China. T. marneffei mainly infects patients with human immunodeficiency virus (HIV) but also infects individuals without known immunosuppression. Here we investigated the involvement of anti-IFN-γ autoantibodies in severe T. marneffei infections in HIV-negative patients. We enrolled 58 HIV-negative adults with severe T. marneffei infections who were otherwise healthy. We found a high prevalence of neutralizing anti-IFN-γ autoantibodies (94.8%) in this cohort. The presence of anti-IFN-γ autoantibodies was strongly associated with HLA-DRB1*16:02 and -DQB1*05:02 alleles in these patients. We demonstrated that adult-onset acquired immunodeficiency due to autoantibodies against IFN-γ is the major cause of severe T. marneffei infections in HIV-negative patients in regions where this fungus is endemic. The high prevalence of anti-IFN-γ autoantibody-associated HLA class II DRB1*16:02 and DQB1*05:02 alleles may account for severe T. marneffei infections in Southeast Asia. Our findings clarify the pathogenesis of T. marneffei infection and pave the way for developing novel treatments.

Calcineurin A Is Essential in the Regulation of Asexual Development, Stress Responses and Pathogenesis in Talaromyces marneffei

Talaromyces marneffei is a common cause of infection in immunocompromised patients in Southeast Asia and Southern China. The pathogenicity of T. marneffei depends on the ability of the fungus to survive the cytotoxic processes of the host immune system and grow inside host macrophages. These mechanisms that allow T. marneffei to survive macrophage-induced death are poorly understood. In this study, we examined the role of a calcineurin homolog (cnaA) from T. marneffei during growth, morphogenesis and infection. Deletion of the cnaA gene in T. marneffei resulted in a strain with significant defects in conidiation, germination, morphogenesis, cell wall integrity, and resistance to various stressors. The ΔcnaA mutant showed a lower minimal inhibitory concentration (MIC) against caspofungin (16 μg/ml to 2 μg/ml) and micafungin (from 32 μg/ml to 4 μg/ml) compared with the wild-type. These results suggest that targeting calcineurin in combination with echinocandin treatment may be effective for life-threatening systemic T. marneffei infection. Importantly, the cnaA mutant was incapable of adapting to the macrophage environment in vitro and displayed virulence defects in a mouse model of invasive talaromycosis. For the first time, a role has been shown for cnaA in the morphology and pathogenicity of a dimorphic pathogenic filamentous fungus.

Characteristics and Prognosis of Talaromyces marneffei Infection in Non-HIV-Infected Children in Southern China

Knowledge about the clinical and laboratory characteristics and prognosis of Talaromyces marneffei infection in children is limited. A retrospective study was conducted on pediatric patients with disseminated T. marneffei infection in a clinical setting. Extracted data included demographic information (age and sex), clinical features, laboratory findings, treatment, and prognosis. Eleven HIV-negative children were enrolled. The male/female ratio was 8:3. The median age of onset was 17.5 months (3.5-84 months). The mortality rate in these children was 36.36% (4/11). Seven children had underlying diseases. All of the children had multiple immunoglobulin abnormalities and immune cell decline. Ten children received voriconazole treatment, and most of the children (7/10) had a complete response to therapy at primary and long-term follow-up assessment; only three children died of talaromycosis. One patient recovered from talaromycosis but died of leukemia. The child who received itraconazole treatment also showed clinical improvement. No adverse events associated with antifungal therapies were recorded during and after the treatment. Talaromycosis is an indicator disease for undiagnosed severe immunodeficiencies in children. Awareness of mycoses in children by pediatricians may prompt diagnosis and timely treatment. Voriconazole is an effective, well-tolerated therapeutic option for disseminated T. marneffei infection in non-HIV-infected children.

In Vitro Susceptibility of Berberine Combined with Antifungal Agents Against the Yeast Form of Talaromyces marneffei

Talaromyces (Penicillium) marneffei can cause fatal disseminated infection in immunocompromised hosts. However, therapeutic strategies for the mycosis are limited. Reports of the other fungi suggest that berberine, a component of traditional herb, inhibitors interact with antifungal agents to improve the treatment outcomes. In the study, we evaluated the in vitro efficacy of berberine in combination with conventional antifungal agents against the pathogenic yeast form of T. marneffei. We demonstrate the synergistic effect of combination of berberine with fluconazole (52.38%), itraconazole (66.67%), voriconazole (71.43%), amphotericin B (71.43%) or caspofungin (52.38%) of T. marneffei strains, respectively. Time-kill curves confirmed the synergistic interaction, and no antagonistic was observed in all of the combinations. In conclusion, berberine could enhance the efficacy of conventional antifungal agents against the yeast form of T. marneffei in vitro. The results indicated berberine might have a potential role in combination therapy for talaromycosis.