Isolation of Penicillium marneffei From Soil and Wild Rodents in Guangdong, SE China

Morphology, Development, and Pigment Production of Talaromyces marneffei are Diversely Modulated Under Physiologically Relevant Growth Conditions

Talaromyces marneffei is an opportunistic pathogenic fungus that mainly affects HIV-positive individuals endemic to Southeast Asia and China. Increasing efforts have been made in the pathogenic mechanism and host interactions understanding of this pathogen in the last two decades; however, there are still no conclusions on how T. marneffei was transmitted from the donor bamboo rats to humans. A perception that the failure of fungus isolation from soil was attributed to the low salt tolerance of T. marneffei. Therefore, the effect of environmental fluctuations in fungal growth and development is fundamental for the characterization of its origin and fungal biology understanding. Herein, we characterized high osmolarity, pH, metal ions, nutrients, and oxidative stress have versatile effects on T. marneffei hyphal or yeast growth, conidia generation, and pigment production. Among these, high pH, low glucose amounts, and the inorganic nitrogen ammonium tartrate stimulated the red pigment production, whereas high osmolarity, high pH, and the inorganic nitrogen sodium nitrate could significantly accelerate the conidia generation. Specifically, zinc starvation repressed conidia generation and prevented the wrinkled yeast colony formation, indicating the function of zinc regulators in pathogenicity regulation. Since conidia are recognized as the infectious propagules, the effects characterization of different environmental factors in T. marneffei morphology in this work will not only expand the growth and pathogenic biology understanding of the fungus but also provide more clues for the T. marneffei infection transmission origin investigation.

An Overlooked and Underrated Endemic Mycosis-Talaromycosis and the Pathogenic Fungus Talaromyces marneffei

Talaromycosis is an invasive mycosis endemic in tropical and subtropical Asia and is caused by the pathogenic fungus Talaromyces marneffei. Approximately 17,300 cases of T. marneffei infection are diagnosed annually, and the reported mortality rate is extremely high (~1/3). Despite the devastating impact of talaromycosis on immunocompromised individuals, particularly HIV-positive persons, and the increase in reported occurrences in HIV-uninfected persons, diagnostic and therapeutic approaches for talaromycosis have received far too little attention worldwide. In 2021, scientists living in countries where talaromycosis is endemic raised a global demand for it to be recognized as a neglected tropical disease. Therefore, T. marneffei and the infectious disease induced by this fungus must be treated with concern. T. marneffei is a thermally dimorphic saprophytic fungus with a complicated mycological growth process that may produce various cell types in its life cycle, including conidia, hyphae, and yeast, all of which are associated with its pathogenicity. However, understanding of the pathogenic mechanism of T. marneffei has been limited until recently. To achieve a holistic view of T. marneffei and talaromycosis, the current knowledge about talaromycosis and research breakthroughs regarding T. marneffei growth biology are discussed in this review, along with the interaction of the fungus with environmental stimuli and the host immune response to fungal infection. Importantly, the future research directions required for understanding this serious infection and its causative pathogenic fungus are also emphasized to identify solutions that will alleviate the suffering of susceptible individuals worldwide.

Key thermally dimorphic fungal pathogens: shaping host immunity

Exposure to fungal pathogens from the environment is inevitable and with the number of at-risk populations increasing, the prevalence of invasive fungal infection is on the rise. An interesting group of fungal organisms known as thermally dimorphic fungi predominantly infects immunocompromised individuals. These potential pathogens are intriguing in that they survive in the environment in one form, mycelial phase, but when entering the host, they are triggered by the change in temperature to switch to a new pathogenic form. Considering the growing prevalence of infection and the need for improved diagnostic and treatment approaches, studies identifying key components of fungal recognition and the innate immune response to these pathogens will significantly contribute to our understanding of disease progression. This review focuses on key endemic dimorphic fungal pathogens that significantly contribute to disease, including Histoplasma, Coccidioides and Talaromyces species. We briefly describe their prevalence, route of infection and clinical presentation. Importantly, we have reviewed the major fungal cell wall components of these dimorphic fungi, the host pattern recognition receptors responsible for recognition and important innate immune responses supporting adaptive immunity and fungal clearance or the failure thereof.

Gastrointestinal manifestations of Talaromyces marneffei infection in an HIV-infected patient rapidly verified by metagenomic next-generation sequencing: a case report

Background

The manifestation of Talaromyces marneffei infection in some HIV-infected patients may be atypical. Cases with gastrointestinal involvement have rarely been reported. It is hard to make a diagnosis when patients are lacking the characteristic rash and positive blood culture.

Case presentation

Here, we described a patient living with HIV who complained of fever and abdominal pain, and was rapidly diagnosed with Talaromyces marneffei infection by metagenomic next-generation sequencing (mNGS) using formalin-fixation and paraffin-embedded (FFPE) samples of omentum majus tissue. We also reviewed reported related cases.

Conclusions

Talaromyces marneffei is an unusual cause of clinical presentations involving obvious abdominal pain and lower gastrointestinal bleeding, but can be included in the differential diagnosis. As an important diagnostic tool, the significance of mNGS using FFPE samples of lesions provides a more targeted diagnosis.

Recurrent Talaromyces marneffei Infection Presenting with Intestinal Obstruction in a Patient with Systemic Lupus Erythematosus

Talaromyces marneffei is an important opportunistic pathogen mainly afflicting the HIV-infected patients, in rare instance, it could cause infection in non-HIV-infected individuals. We report a 51-year-old Chinese woman who, with histories of SLE for 14 years and disseminated talaromycosis for 4 years, occurred partial intestinal obstruction that was demonstrated to be caused by Talaromyces marneffei infection. The randomly amplified polymorphic DNA results of paraffin-embedded tissues from both the present episode and the previous infection suggested that the present infection was a recurrent. The patient was performed excision of involved intestine and treated with oral itraconazole at a daily dose of 400 mg for 3 months, leading to an excellent response. However, she died with unknown reason more than a year later. We also reviewed the literature on Talaromyces marneffei infection associated with SLE as well as intestinal talaromycosis alone.

AIDS-associated Talaromyces marneffei central nervous system infection in patients of southwestern China

Background

The clinical and laboratory characteristics of AIDS-associated Talaromyces marneffei infection, a rare but a fatal mycosis disease of the central nervous system, remain unclear.

Case presentation

Herein, we conducted a retrospective study of ten AIDS patients with cerebrospinal fluid culture-confirmed central nervous system infection caused by Talaromyces marneffei. All 10 patients were promptly treated with antifungal treatment for a prolonged duration and early antiviral therapy (ART). Among them, seven patients were farmers. Nine patients were discharged after full recovery, while one patient died during hospitalization, resulting in a mortality rate of 10%. All patients initially presented symptoms and signs of an increase in intracranial pressure, mainly manifesting as headache, dizziness, vomiting, fever, decreased muscle strength, diplopia or even altered consciousness with seizures in severe patients. Nine patients (90%) showed lateral ventricle dilatation or intracranial infectious lesions on brain CT. Cerebrospinal fluid findings included elevated intracranial pressure, increased leukocyte count, low glucose, low chloride and high cerebrospinal fluid protein. The median CD4⁺ T count of patients was 104 cells/μL (IQR, 36–224 cells/μL) at the onset of the disease. The CD4⁺ T cell counts of three patients who eventually died were significantly lower (W = 6.00, p = 0.020) than those of the patients who survived.

Conclusions

The common clinical symptoms of T. marneffei central nervous system infection are associated with high intracranial pressure and intracranial infectious lesions. Earlier recognition and diagnosis and a prolonged course of amphotericin B treatment followed by itraconazole combined with early ART might reduce the mortality rate.

Determinants of prognosis in Talaromyces marneffei infections with respiratory system lesions

Background:

Little study has investigated the differences between Talatomyces marneffei (T. marneffei) respiratory infection and tuberculosis and the prognostic factors of such infection. This study investigated the characteristics and prognostic factors of T. marneffei infections with respiratory lesions and the causes of misdiagnosis.

Methods:

Clinical characteristics and prognoses of patients with T. marneffei infections with respiratory system lesion were investigated. T. marneffei diagnosis followed isolation from clinical specimens using standard culture, cytology, and histopathology. Survival curves were estimated by using Kaplan-Meier analysis, with log-rank test to compare differences in survival rates between groups. Univariate and multivariate Cox regression analyses were also performed to assess significant differences in clinical characteristics of overall survival.

Results:

Of 126 patients diagnosed with T. marneffei infections, 63 (50.0%) had T. marneffei respiratory system infections; 38.1% (24/63) were misdiagnosed as having tuberculosis. Human immunodeficiency virus (HIV) infection, CD4/CD8 < 0.5, percentage of CD4⁺ T cells <42.8%, and length of time from onset to confirmation of diagnosis >105 days were potential risk factors for poor prognoses. Length of time from onset to confirmation of diagnosis persisted as an independent predictor of all-cause mortality in multivariate analysis (odds ratio: 0.083, 95.0% confidence interval: 0.021–0.326, P < 0.001). However, the size of the lung lesions, dyspnea, thoracalgia, mediastinal lymphadenopathy, and pleural effusion did not significantly predict overall survival. There was no significant difference in prognosis according to the type of treatment.

Conclusions:

T. marneffei infections involving the respiratory system are common. The critical determinants of prognosis are HIV infection, CD4/CD8, percentage of CD4⁺ T cells, type of treatment, and the time range from onset to confirmation of diagnosis. Rapid and accurate diagnosis is crucial for improving prognosis.

First report of Giardia duodenalis infection in bamboo rats

Background

The zoonotic parasite, Giardia duodenalis (syns. G. lamblia and G. intestinalis), has been widely reported in humans and animals, including rodents. The bamboo rat, a rodent species belonged to the subfamily Rhizomyinae, is farmed in China because of its medicinal and edible values. However, no information of G. duodenalis infection was available in bamboo rats prior to the present study. Here, the prevalence and genetic diversity of G. duodenalis in bamboo rats from Hunan Province of China were investigated.

Results

Of 480 faecal samples collected from six farms located in four cities (Wugang, Chenzhou, Huaihua and Jishou) of Hunan Province, 52 (10.8%) were positive for G. duodenalis infection by using a nested PCR approach targeting the beta giardin (bg) gene. Significant differences (P < 0.01) in prevalence were found among different age groups and geographical localities, and among different farms in Wugang city. Sequence analysis revealed existence of the zoonotic assemblage B and genetic diversity of G. duodenalis in these animals. Multilocus genotyping analysis also indicated broad genetic diversity of assemblage B isolates in these bamboo rats.

Conclusions

This is the first report of the infection and genetic variations of G. duodenalis in bamboo rats. These findings will provide basic data for implementing effective strategies to control giardiasis in bamboo rats.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3111-2) contains supplementary material, which is available to authorized users.

Disseminated Penicillium marneffei infection recurrence in a non-acquired immune deficiency syndrome patient: A case report

Penicillium marneffei is a rare deep tissue fungal infection causing an endemic in Southeast Asia. This infection causes penicilliosis disease and is more common in patients who are immunocompromised. To date, no cases of P. marneffei infection relapse following treatment have been reported. A 36-year-old patient attended our hospital as a result of intermittent fever, cough, shortness of breath and multiple soft lesions located on the face, arms, neck and trunk. The medical radiological examination of the lung revealed multiple patchy exudative shadows, thick-walled hollow inner part of the visible lesions, bilateral pleural and pericardial effusion. Assessing the skull and right collarbone, bilateral thoracic ribs and a plurality revealed numeorus lesions with reduced bone destruction and revealed that the patient was positive for P. marneffei infection. After 6 months of antifungal therapy, pulmonary symptoms and the surface lesions of the patient rapidly disappearance and the physical condition markedly improved. The patient did not attend a follow-up and stopped antifungal treatment. In February 2016, the patient presented with left breast and subcutaneous soft tissue mass of the head and neck. Fungal culture results revealed that the patient was again positive for P. marneffei infection. The present case suggested that clinical doctors and patients must pay more attention to regular treatment of the disseminated P. marneffei. It also highlighted the requirement for awareness of penicilliosis in non-acquired immune deficiency syndrome patients, who are not immunocompromised, who are living in or traveling to P. marneffei-endemic areas.

Organism-wide studies into pathogenicity and morphogenesis in Talaromyces marneffei

Organism-wide approaches examining the genetic mechanisms controlling growth and proliferation have proven to be a powerful tool in the study of pathogenic fungi. For many fungal pathogens techniques to study transcription and protein expression are particularly useful, and offer insights into infection processes by these species. Here we discuss the use of approaches such as differential display, suppression subtractive hybridization, microarray, RNA-seq, proteomics, genetic manipulation and infection models for the AIDS-defining pathogen Talaromyces marneffei. Together these methods have broadened our understanding of the biological processes, and genes that underlie them, which are involved in switching between the saprophytic and pathogenic states of T. marneffei, the maintenance of these two specialized cell types and its ability to cause disease.

Role of Rhizomys pruinosus as a natural animal host of Penicillium marneffei in Guangdong, China

Penicillium marneffei, a dimorphic fungus that can cause penicilliosis marneffei, is endemic in Southeast Asia. The only known hosts of P. marneffei are humans and bamboo rats. The aim of our study was to explore the distribution of P. marneffei in bamboo rats, their associated environment and non-rat-associated environments. Totally, 270 samples were collected in Guangdong province of China in 2012; the prevalence of P. marneffei was much higher in samples collected from surrounding areas of burrows (8.2%) than in the samples obtained from non-rat-associated sites (2%) or artificial farms of bamboo rats (0%). There was no difference in P. marneffei isolated rate from different areas of Guangdong province. The infection is prevalent in all rats, and this fungus could be frequently seen in the rats' lungs. This study confirms that bamboo rat is the ecological niche of P. marneffei and hypothesizes that bamboo rats become infected by inhaling aerosolized conidia originating from environmental sources, rather than by the fecal-oral route or transplacental crossing. According to the result of no detection of P. marneffei in the artificial farm, the activity of bamboo rats might be more relevant to the distribution and dissemination of P. marneffei in natural environment.

Penicillium marneffei infection: an emerging disease in mainland China

Penicillium marneffei is an emerging pathogenic fungus that can cause a life-threatening systemic mycosis in immunocompromised hosts, especially in patients with AIDS. This infection is endemic in Southeast Asia. With the prevalence of AIDS in this area, the number of patients with systemic penicilliosis marneffei is found to be increasing rapidly in mainland China in recent years. We recently reviewed 668 cases of penicilliosis marneffei in mainland China from January 1984 to December 2009 in cnki, cqvip, CBMdisc and PubMed. We analyzed epidemiological and clinical features, laboratory findings, reaction to therapy and prognosis of the disease. We found that 99.4% of the cases were reported in the southern part of China; among these cases, 42.8% were from Guangxi (286 cases) and 40.6% were from Guangdong province (271 cases). Five hundred and eighty-six cases (87.7%) of penicilliosis marneffei were reported with infection by the human immunodeficiency virus, 25 cases (3.8%) with other immunocompromised diseases, and 57 cases (8.5%) without any documented underlying diseases. Fever, weight loss, anemia, lymphadenopathy, hepatosplenomegaly, respiratory signs and skin lesions were the common clinical manifestations of P. marneffei infections. The 569 cases received antifungal therapy with a mortality of 24.3% (138 cases), 99 cases who had not received antifungal therapy had a mortality of 50.6%. P. marneffei was an emerging pathogenic fungus and become a medical and public health importance in mainland China. The immunocompromised patients should pay more attention to P. marneffei infection in the endemic areas.