Comparing the profile of respiratory fungal pathogens amongst immunocompetent and immunocompromised hosts, their susceptibility pattern and correlation of various opportunistic respiratory fungal infections and their progression in relation to the CD4+T-cell counts

Diagnosis and Treatment of Invasive Aspergillosis Caused by Non-fumigatus Aspergillus spp

With increasing frequency, clinical and laboratory-based mycologists are consulted on invasive fungal diseases caused by rare fungal species. This review aims to give an overview of the management of invasive aspergillosis (IA) caused by non-fumigatus Aspergillus spp.-namely A. flavus, A. terreus, A. niger and A. nidulans-including diagnostic and therapeutic differences and similarities to A. fumigatus. A. flavus is the second most common Aspergillus spp. isolated in patients with IA and the predominant species in subtropical regions. Treatment is complicated by its intrinsic resistance against amphotericin B (AmB) and high minimum inhibitory concentrations (MIC) for voriconazole. A. nidulans has been frequently isolated in patients with long-term immunosuppression, mostly in patients with primary immunodeficiencies such as chronic granulomatous disease. It has been reported to disseminate more often than other Aspergillus spp. Innate resistance against AmB has been suggested but not yet proven, while MICs seem to be elevated. A. niger is more frequently reported in less severe infections such as otomycosis. Triazoles exhibit varying MICs and are therefore not strictly recommended as first-line treatment for IA caused by A. niger, while patient outcome seems to be more favorable when compared to IA due to other Aspergillus species. A. terreus-related infections have been reported increasingly as the cause of acute and chronic aspergillosis. A recent prospective international multicenter surveillance study showed Spain, Austria, and Israel to be the countries with the highest density of A. terreus species complex isolates collected. This species complex seems to cause dissemination more often and is intrinsically resistant to AmB. Non-fumigatus aspergillosis is difficult to manage due to complex patient histories, varying infection sites and potential intrinsic resistances to antifungals. Future investigational efforts should aim at amplifying the knowledge on specific diagnostic measures and their on-site availability, as well as defining optimal treatment strategies and outcomes of non-fumigatus aspergillosis.

Increased susceptibility of irradiated mice to Aspergillus fumigatus infection via NLRP3/GSDMD pathway in pulmonary bronchial epithelia

Background

Aspergillus fumigatus infection is difficult to diagnose clinically and can develop into invasive pulmonary aspergillosis, which has a high fatality rate. The incidence of Aspergillus fumigatus infection has increased die to widespread application of radiotherapy technology. However, knowledge regarding A. fumigatus infection following radiation exposure is limited, and the underlying mechanism remains unclear. In this study, we established a mouse model to explore the effect of radiation on A. fumigatus infection and the associated mechanisms.

Methods

In this study, a mouse model of A. fumigatus infection after radiation was established by irradiating with 5 Gy on the chest and instilling 5 × 10⁷/ml Aspergillus fumigatus conidia into trachea after 24 h to explore the effect and study its function and mechanism. Mice were compared among the following groups: normal controls (CON), radiation only (RA), infection only (Af), and radiation + infection (RA + Af). Staining analyses were used to detect infection and damage in lung tissues. Changes in protein and mRNA levels of pyroptosis-related molecules were assessed by western blot analysis and quantitative reverse transcription polymerase chain reaction, respectively. Protein concentrations in the serum and alveolar lavage fluid were also measured. An immunofluorescence colocalization analysis was performed to confirm that NLRP3 inflammasomes activated pyroptosis.

Results

Radiation destroyed the pulmonary epithelial barrier and significantly increased the pulmonary fungal burden of A. fumigatus. The active end of caspase-1 and gasdermin D (GSDMD) were highly expressed even after infection. Release of interleukin-18 (IL-18) and interleukin-1β (IL-1β) provided further evidence of pyroptosis. NLRP3 knockout inhibited pyroptosis, which effectively attenuated damage to the pulmonary epithelial barrier and reduced the burden of A. fumigatus.

Conclusions

Our findings indicated that the activation of NLRP3 inflammasomes following radiation exposure increased susceptibility to A. fumigatus infection. Due to pyroptosis in lung epithelial cells, it resulted in the destruction of the lung epithelial barrier and further damage to lung tissue. Moreover, we found that NLRP3 knockout effectively inhibited the pyroptosis and reducing susceptibility to A. fumigatus infection and further lung damage. Overall, our results suggest that NLRP3/GSDMD pathway mediated-pyroptosis in the lungs may be a key event in this process and provide new insights into the underlying mechanism of infection.

Profiling of potential pulmonary fungal pathogens and the prevalence of the association between pulmonary tuberculosis and potential fungal pathogens in presumptive tuberculosis patients referred to Saint Peter's Specialized Tuberculosis Referral Hospital, Addis Ababa, Ethiopia

Objective

The burden of pulmonary fungal infection is increasing and often misdiagnosed as pulmonary tuberculosis in developing countries where the prevalence of pulmonary tuberculosis is high. |Therefore, the purpose of this study is to determine the spectrum of potential pulmonary fungal pathogens and the prevalence of the association between pulmonary tuberculosis and potential fungal pathogens.

Materials and methods

A cross-sectional study was conducted between October 2018 and May 2019. Sputum was collected from 636 study participants. Part of the sputum was inoculated onto Brain Heart Infusion agar, and fungi were identified following standard microbiological procedures. The remaining part of the sample was used for the investigation of pulmonary tuberculosis.

Results

Among 636 sputum samples, 75.9% (483) and 25.6% (163) were positive for potential fungal pathogens and pulmonary tuberculosis, respectively. The prevalence of the association between pulmonary tuberculosis and potential fungal pathogens was 20.0%. Of fungal isolates, 81.4% were yeasts. The remaining 128 (18.6%) isolates were molds. The isolation rate of fungi was higher in males (51.6%) than in females (48.4%). There was no statistically significant association between the prevalence of potential pulmonary fungal pathogens and sex (p = 0.239). Patients in the age group of 35 to 44 and above were slightly more affected than younger age groups. The association between potential fungal pathogens and age was not statistically significant (p = 0.50).

Conclusion

High prevalence of potential pulmonary fungal pathogens and the association of tuberculosis and potential fungal pathogens recorded in this study will enforce health personnel to pay due attention to these conditions and arise the interest of researchers to conduct further work on the burden of the association between tuberculosis and potential fungal pathogens. Our study also revealed the need to employ conventional microbiology tests along with clinical and radiological evidence since clinical manifestations and radiological pictures of tuberculosis mimic that of pulmonary fungal infection.

Epidemiology, laboratory diagnosis and clinical aspects of fungal pulmonary infections in 384 patients hospitalized in pulmonary units in Guilan province, Iran

Background and Objectives:

The respiratory tract is the most common site for developing fungal infections. People who have a weakened immune system are more susceptible to respiratory system involvement with fungi. Fungal infections of the respiratory tract are largely unrecognized and their true burden is elusive. Therefore, the aim of the current study was to evaluate the clinical spectrum, demographic characteristics, risk factors, and etiology of fungal respiratory infections in 384 patients hospitalized in pulmonary units of Razi hospital, Guilan province, Iran.

Materials and Methods:

A total of 384 lung specimens (192 Bronchoalveolar lavages (BAL) and 192 sputa) were obtained from patients who met the inclusion criteria. All samples were analyzed by direct microscopy and culture. Fungal identification was accomplished by internal transcribed spacer (ITS) and beta-tubulin sequencing. Also, in patients suspected to invasive pulmonary aspergillosis BAL specimens were tested for galactomannan (GM) antigen. According to the host factors (clinical symptoms, radiology findings and predisposing factors which were defined as inclusion criteria), and the positive results in direct examination, culture and serology (GM for aspergillosis) the infection was confirmed.

Results:

Fungal respiratory infection was confirmed in 137 cases (35.67%) including 86 (62.77%) males and 51 (37.23%) females and the highest prevalence of infection was found in the age group of 46–72 years (n=75, 54.74%). Cough (n=129, 94.16%), dyspnea (n=111, 81.02%), purulent sputum (n=85, 62.04%) and weight loss (n=77, 56.2%) were the predominant symptoms. Tuberculosis (n=34, 24.81%), taking chemotherapy regimen (n=30, 21.89%) and diabetes mellitus (n=27, 19.70%) were the predominant underlying conditions. Candida albicans (37.22%) and Candida tropicalis (21.89%) represent the two most commonly isolated species in the current study. Furthermore, according to revised EORTC/MSG (2008) definitions for invasive fungal infections, from 5 cases of pulmonary aspergillosis, 2 (40%) cases of probable invasive pulmonary aspergillosis (IPA) and 3 (60%) cases of possible IPA were diagnosed.

Conclusion:

According to the results of this study, infected infants with congenital CMV infection could identify at early stage by testing Guthrie cards (within 21 days of life). Furthermore, since there is a lack of CMV knowledge in our population, educating and effective counseling by obstetricians/gynecologists to the pregnant women are recommended.

Fungal Isolates of the Respiratory Tract in Symptomatic Patients Hospitalized in Pulmonary Units: A Mycological and Molecular Epidemiologic Study

Introduction

Fungal respiratory infections are being recognized with increasing frequency in parallel with an expanding population of immunocompromised patients. In most cases, colonization is the first step in the progression to pulmonary fungal infection. This study was designed to evaluate the distribution of fungal elements in the respiratory tract of symptomatic patients hospitalized in pulmonary units.

Methods

This descriptive cross-sectional study was carried out over a period of two years, from October 2017 to October 2019 in Guilan province, located in Iran’s northern region. In the current study, bronchoalveolar lavage or sputum specimens were collected. All samples were analyzed by direct microscopy using KOH 10% and culture. Fungal identification was accomplished by internal transcribed spacer (ITS) and beta-tubulin sequencing. Also, in patients suspected of invasive pulmonary aspergillosis, BAL specimens were tested for galactomannan (GM) antigen.

Results

A total of 384 lung specimens (192 bronchoalveolar lavage (BAL) and 192 sputum samples) were obtained from symptomatic patients hospitalized in pulmonary units. Of these, 137 (35.67%) were positive in direct examination and culture. Among the 137 positive cases, most isolates were from male patients 86 (62.77%) and most of them were between 46 and 72 years. Candida albicans (37.22%) and Candida tropicalis (21.89%) represent the two most commonly isolated species in the current study. Cough (94.16%), dyspnea (81.02%), purulent sputum (62.04%) and weight loss (56.2%) were the predominant symptoms and tuberculosis (24.81%), chemotherapy (21.89%) and diabetes mellitus (19.70%) were the predominant underlying conditions. Also, 5 cases of invasive pulmonary aspergillosis and 1 case of mucormycosis were diagnosed.

Conclusion

Candida albicans was the most common fungal species isolated from symptomatic patients hospitalized in pulmonary units. Tuberculosis, chemotherapy and diabetes mellitus were important underlying conditions for pulmonary fungal colonization and/or infection.