PD-related peritonitis from Psathyrella candolleana caused by poor PD catheter belt hygiene

Peritoneal dialysis (PD)-associated fungal peritonitis, although rare, presents significant challenges in diagnosis and management. Here, we present the first case of PD-related peritonitis attributed to Psathyrella candolleana and highlight a potential route of infection through contamination from the PD catheter belt. A 37-year-old female, with a history of heart and lung transplantation and undergoing continuous ambulatory PD, presented with acute abdominal pain and cloudy PD effluent (PDE). Genetic analysis of PDE and PD catheter tip confirmed diagnosis of P. candolleana. Treatment was successful without any relapses with timely PD catheter removal and an extended course of antifungal therapy. The root cause analysis suspected the dirt-stained PD catheter belt as the origin of contamination. In conclusion, this is the first case of P. candolleana infection in PD-related peritonitis. Preventive strategies should prioritize hygiene practices, including the PD belt to mitigate the risk of contamination and subsequent infections of such pathogens.

Invasive aspergillosis due to cryptic Aspergillus species: A prospective study from a single centre in India

BACKGROUND

& objective: The existence of visually identical cryptic Aspergillus species that can be distinguished only by molecular techniques is becoming more widely acknowledged. For the majority of antifungal drugs, these are known to exhibit a greater minimal inhibitory concentration in vitro. For the purpose of receiving the proper care, it is crucial to identify these species at right time. Our aim in this work is to identify and describe the Aspergillus species that are cryptic from all of the clinical samples.

METHODS

Routine samples from inpatients and outpatients received in department of Microbiology, All India Institute of Medical Sciences, New Delhi, showing growth of Aspergillus species were included in this study. Phenotypic and Matrix Assisted Laser Desorption Ionisation - Time of Flight identified isolates were analysed for cryptic species, by PCR and ITS/ß - tubulin sequencing. In accordance with CLSI recommendations, antifungal susceptibility testing was conducted using micro broth dilution.

RESULTS

Of the 94 isolates, 54 A. fumigatus, 34 A. flavus, 3 A. nidulans, 2 A. terreus, and 1 A. niger were morphologically identified. MALDI-TOF misidentified 2 A. nidulans isolates and 1 A, stellatus isolate. The ß - tubulin sequence analysis revealed that 2 isolates (2.08 %) were cryptic, one was A. stellatus and another one was A. tubingensis.

Innate and Adaptive Immune Responses Induced by Aspergillus fumigatus Conidia and Hyphae

Previous research indicated that hyphae of Aspergillus fumigatus (A. fumigatus) rather than conidia could successfully build a pulmonary aspergillosis model in immunocompetent mice. In this study, we compared the immune responses induced by hyphae and conidia to explore the possible mechanism of this striking phenomenon. Herein, a novel method was designed and adopted to quantify hyphal fragments. Murine macrophages RAW264.7 and human peripheral blood mononuclear cells were stimulated by A. fumigatus hyphae and conidia in vitro, respectively, and then immunological reactions were measured. Male C57BL/6 mice were challenged with conidia and hyphae through intratracheal inoculation. Dynamic conditions of mice were recorded, and RNA-seq measured corresponding immune responses. The results of the study confirmed that hyphae could induce more intensive inflammation than conidia in vitro and in vivo. However, macrophages revealed a higher production of ROS and M1 polarisation in response to conidia stimuli. Additionally, conidia could promote Th1 cell differentiation, while hyphae could increase the CD4/CD8 ratio. RNA-seq validated the fact that those multiple immunologically relevant pathways were more strongly activated by hyphae than conidia, which also promoted Th2 cell differentiation and suppressed Th1 signalling. Both hyphae and conidia could activate Th17 signalling. In general, conidia and hyphae induced distinctly different host immune responses, and the immune responses induced by conidia played a better protective effect. Therefore, the unique function of hyphae in the spread and infection of Aspergillus should be emphasised, and more research is required to clarify the underlying mechanisms for better understanding and management of aspergillosis.