Description of a Murine Model of Pneumocystis Pneumonia

Pneumocystis pneumonia is a serious lung infection caused by an original ubiquitous fungus with opportunistic behavior, referred to as Pneumocystis jirovecii. P. jirovecii is the second most common fungal agent among invasive fungal infections after Candida spp. Unfortunately, there is still an inability to culture P. jirovecii in vitro, and so a great impairment to improve knowledge on the pathogenesis of Pneumocystis pneumonia. In this context, animal models have a high value to address complex interplay between Pneumocystis and the components of the host immune system. Here, we propose a protocol for a murine model of Pneumocystis pneumonia. Animals become susceptible to Pneumocystis by acquiring an immunocompromised status induced by iterative administration of steroids within drinking water. Thereafter, the experimental infection is completed by an intranasal challenge with homogenates of mouse lungs containing Pneumocystis murina. The onset of clinical signs occurs within 5 weeks following the infectious challenge and immunosuppression can then be withdrawn. At termination, lungs and bronchoalveolar lavage (BAL) fluids from infected mice are analyzed for fungal load (qPCR) and immune response (flow cytometry and biochemical assays). The model is a useful tool in studies focusing on immune responses initiated after the establishment of Pneumocystis pneumonia.

Deep-seated dermatophytosis caused by Trichophyton rubrum in patient with Becker muscular dystrophy

Trichophyton rubrum is a common fungal pathogen that usually causes superficial infection limited to epidermis only, so called dermatophytosis. However in immunocompromised patients, dermatophytosis can be exceptionally more invasive with extensive lesions involving deep tissues and generating sometimes systemic course. We report the case of a 43-year-old heart transplanted man, who presented with multiple deep-seated nodules and papules in the inguinal areas and in the buttocks. Involvement of Trichophyton rubrum was confirmed by culture, DNA sequencing and histological examination that showed granulomatous inflammatory infiltrates with the presence of hyphae in the dermis. Antifungal therapy with oral terbinafine for four weeks was successful; in spite of initial remnant atrophic scars, the lesions were completely cleared after four month evolution. Deep-seated invasive dermatophytosis is rare, but should be considered with immunocompromised conditions, especially when history of previous superficial dermatophytosis is present.

P468 Aspergillosis in a colony of Humboldt penguins (Spheniscus humboldti) under managed care: a clinical and environmental investigation in a French zoological park

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM

 

Objectives

Aspergillosis is an opportunistic fungal infection due to Aspergillus spp., and primarily A. fumigatus. The disease is pervasive in avian populations, especially those under managed care. The incidence and the management of avian aspergillosis can be critically impacted by exposure to high levels of spores via environmental contamination and by strains resistant to azole drugs. The present study aimed at assessing the impact of environmental contamination on the clinical incidence of aspergillosis in penguins managed under human care. ZooParc de Beauval was chosen for the investigations, because this zoological facility hosts a large colony of Humboldt penguin (Spheniscus humboldti) and it is geographically located in the rural countryside of the Loir-et-Cher district, France, surrounded by numerous large crop fields

Material and methods

The fungal contamination in the environment was assessed through three serial sessions of surface sampling in bird nests: all isolates were counted, identified by DNA sequencing, and then systematically screened for resistance mutations and MICs (minimal inhibitory concentrations) elevation for the A. fumigatus strains. In addition, the clinical incidence of aspergillosis was evaluated in the penguin population over a 3-year period. A microsatellite-based analysis tracked A. fumigatus isolates circulation.

Results

Environmental investigations highlighted a substantial increase in the fungal load during the Autumn season (>12-fold vs. the other timepoints) and a large overrepresentation of species belonging to the Aspergillus section Fumigati (ranging from 22.7 to 94.6%) (Fig. 1). Only one cryptic species (A. nishimurae) and one isolate exhibiting resistance mutation (G138S in the cyp51A gene; MIC itraconazole >4 μg/ml) were detected. The overall incidence of aspergillosis was measured at ∼3.4% case-years and was observed mostly in juvenile penguins (Fig. 1). The analysis of microsatellite polymorphism revealed a high level of genetic diversity among A. fumigatus isolates, except for one strain that was largely over-represented during the Autumn sampling session. A limited number of isolate genotypes was collected from clinical cases and from the environment.

Conclusions

Fungal environmental contamination and incidence of aspergillosis in penguins appeared variable depending on seasons, but the rural location of the penguin habitat did not seem to influence the emergence of resistant strains.

P044 Demonstration of the yeasticidal efficacy of povidone-iodine-based commercial antiseptic solutions against Candida auris

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM

 

Objectives

Candida auris is an emerging yeast pathogen with worldwide distribution and a great propensity for nosocomial spread. Recent reports have warned of the significant emergence of C. auris in several healthcare facilities. In order to stop its nosocomial transmission, use of antiseptics constitutes the first-line lever of action in fighting against C. auris skin colonization. However, little is known about the efficacy of these products, and moreover, no antiseptics are currently registered for use against C. auris.

Material and Methods

This study investigated the in vitro yeasticidal activity of povidone-iodine (Betadine®) against C. auris, and compared the findings to C. albicans and C. glabrata.

Results

In all the samples, the fungal load was substantially reduced by ≥4.2 Log10 colony-forming units, according to the EN standard 1275:2005. Moreover, even when largely diluted, povidone-iodine products still allowed a sustainable decrease of the yeast viability below 0.1%.

Conclusion

Overall, these results support the use of such commercial antiseptics in the context of colonization with this yeast.

Challenges to establish the diagnosis of aspergillosis in non-laboratory animals: looking for alternatives in veterinary medicine and demonstration of feasibility through two concrete examples in penguins and dolphins

Aspergillosis remains difficult to diagnose in animals. Laboratory-based assays are far less developed than those for human medicine, and only few studies have been completed to validate their utility in routine veterinary diagnostics. To overcome the current limitations, veterinarians and researchers have to propose alternative methods including extrapolating from human diagnostic tools and using innovative technology. In the present overview, two specific examples were complementarily addressed in penguins and dolphins to illustrate how is challenging the diagnosis of aspergillosis in animals. Specific focus will be made on the novel application of simple testing in blood based on serological assays or protein electrophoresis and on the new information garnered from metabolomics/proteomics to discover potential new biomarkers. In conclusion, while the diagnostic approach of aspergillosis in veterinary medicine cannot be directly taken from options developed for human medicine, it can certainly serve as inspiration.

pAspergillosis in a colony of Humboldt penguins (Spheniscus humboldti) under managed care: a clinical and environmental investigation in a French zoological park

Aspergillosis is pervasive in bird populations, especially those under human care. Its management can be critically impacted by exposure to high levels of conidia and by resistance to azole drugs. The fungal contamination in the environment of a Humboldt penguin (Spheniscus humboldti) group, housed in a French zoological park next to numerous large crop fields, was assessed through three serial sessions of surface sampling in nests, in 2018-20: all isolates were counted and characterized by sequencing. When identified as A. fumigatus, they were systematically screened for resistance mutations in the cyp51A gene and tested for MICs determination. In the same time, the clinical incidence of aspergillosis was evaluated in the penguin population by the means of systematic necropsy and mycological investigations. A microsatellite-based analysis tracked the circulation of A. fumigatus strains. Environmental investigations highlighted substantial increase of the fungal load during the summer season (>12-fold vs. the other timepoints) and large overrepresentation of species belonging to the Aspergillus section Fumigati, ranging from 22.7 to 94.6% relative prevalence. Only one cryptic species was detected (A. nishimurae), and one isolate exhibited G138S resistance mutation with elevated MICs. The overall incidence of aspergillosis was measured at ∼3.4% case-years, and mostly in juveniles. The analysis of microsatellite polymorphism revealed a high level of genetic diversity among A. fumigatus clinical isolates. In contrast, one environmental strain appeared largely overrepresented during the summer sampling session. In all, the rural location of the zoo did not influence the emergence of resistant strains.

Pneumocystis Pneumonia: Pitfalls and Hindrances to Establishing a Reliable Animal Model

Pneumocystis pneumonia is a severe lung infection that occurs primarily in largely immunocompromised patients. Few treatment options exist, and the mortality rate remains substantial. To develop new strategies in the fields of diagnosis and treatment, it appears to be critical to improve the scientific knowledge about the biology of the Pneumocystis agent and the course of the disease. In the absence of in vitro continuous culture system, in vivo animal studies represent a crucial cornerstone for addressing Pneumocystis pneumonia in laboratories. Here, we provide an overview of the animal models of Pneumocystis pneumonia that were reported in the literature over the last 60 years. Overall, this review highlights the great heterogeneity of the variables studied: the choice of the host species and its genetics, the different immunosuppressive regimens to render an animal susceptible, the experimental challenge, and the different validation methods of the model. With this work, the investigator will have the keys to choose pivotal experimental parameters and major technical features that are assumed to likely influence the results according to the question asked. As an example, we propose an animal model to explore the immune response during Pneumocystis pneumonia.

Health threat caused by fungi of medical interest: where are we in 2021?

No abstract present.

From strongyloidiasis to disseminated mucormycosis: the story of an HTLV-1-infected migrant

Strongyloidiasis manifestations range from asymptomatic cases to the life-threatening disseminated strongyloidiasis in case of immune deficiency: larvae migrate throughout the body, disseminating germs from the digestive flora to various organs. Here, we described a case of disseminated mucormycosis consecutive to Strongyloides stercoralis hyperinfestation in a Surinamese migrant infected with HTLV-1.

Demonstration of the yeasticidal efficacy of povidone-iodine-based commercial antiseptic solutions against Candida auris

Candida auris is an emerging yeast pathogen with worldwide distribution and a great propensity for nosocomial spread. Recent reports have warned of the significant emergence of C. auris in several healthcare facilities. In order to stop its nosocomial transmission, use of antiseptics constitutes the first-line lever of action in the fighting against C. auris skin colonization. However, little is known about the efficacy of these products, and moreover no antiseptics are currently registered for use against C. auris. This study investigated the in vitro yeasticidal activity of povidone-iodine against C. auris, and compared the findings to C. albicans and C. glabrata, according to the EN standard 1275:2005. Results support the use of such commercial antiseptics in the context of colonization with this yeast.

Candida nivariensis: Identification strategy in mycological laboratories

Candida nivariensis is a cryptic fungal species classified within the Candida glabrata complex. It was described for the first time in 2005 by the means of DNA sequencing. We report a rare case of C. nivariensis deep-seated infection occurring in a 77-year-old man hospitalized for cysto-prostatectomy. Phenotypic testing based on the direct examination and the macroscopic features of the in vitro culture initially suggested C. glabrata species, while MALDI-TOF mass spectrometry enables correct identification. The isolate was found resistant to fluconazole, like in almost 20% of the reported cases. Herein, we present our practical strategy to reliably characterize this rare cryptic species. To date, MALDI-TOF mass spectrometry-based analysis showed very good results for such a purpose.

Combination of β-(1, 3)-D-glucan testing in serum and qPCR in nasopharyngeal aspirate for facilitated diagnosis of Pneumocystis jirovecii pneumonia

BACKGROUND

Currently, the biological diagnosis of Pneumocystis jirovecii pneumonia (PjP infection) usually relies on microbiological investigations in bronchial-alveolar lavage fluid (BALF) by conventional staining methods and/or molecular biology. However, bronchial-alveolar lavage is sometimes complicated to manage, especially in weakened patients. Therefore, alternative clinical samples-easier to collect-are warranted in such specific contexts.

OBJECTIVE

Over a four-year period, diagnostic performance of an original method based on combination of quantitative real-time polymerase chain reaction (qPCR) in nasopharyngeal aspirate (NPA) with measurement of β-(1, 3)-D-glucan antigen (BDG) in serum was prospectively assessed in a single centre.

PATIENTS/METHODS

Results were compared with those obtained in BALF through direct staining methods and qPCR. True positives were defined by an independent committee based on clinical, radiological and biological data. Overall, 48 individuals with a definitive diagnosis of PjP infection were included, and 48 controls were selected upon matching for age, sex and underlying disease(s).

RESULTS

qPCR results were strongly correlated between BALF and NPA (P < .0001). Altogether, greater diagnostic performance was achieved when establishing the positive cut-off of BDG antigen at 143 pg/mL. In such conditions, sensitivity of the testing based on either positive BDG measurement or positive qPCR in NPA was then calculated at 93.75%, _95% CI [82.37%-98.40%], and specificity at 97.87%, _95% CI [87.66%-100.00%].

CONCLUSIONS

Further validation through multicentre studies is now required, especially for establishing clear cut-offs. However, one could already state that combination of qPCR in the NPA with BDG measurement in serum may be a valuable substitute for BALF examination.

Targeting Aspergillus fumigatus Crf Transglycosylases With Neutralizing Antibody Is Relevant but Not Sufficient to Erase Fungal Burden in a Neutropenic Rat Model

Aspergillus fumigatus is an airborne opportunistic fungal pathogen responsible for severe infections. Among them, invasive pulmonary aspergillosis has become a major concern as mortality rates exceed 50% in immunocompromised hosts. In parallel, allergic bronchopulmonary aspergillosis frequently encountered in cystic fibrosis patients, is also a comorbidity factor. Current treatments suffer from high toxicity which prevents their use in weakened subjects, resulting in impaired prognostic. Because of their low toxicity and high specificity, anti-infectious therapeutic antibodies could be a new alternative to conventional therapeutics. In this study, we investigated the potential of Chitin Ring Formation cell wall transglycosylases of A. fumigatus to be therapeutic targets for therapeutic antibodies. We demonstrated that the Crf target was highly conserved, regardless of the pathophysiological context; whereas the CRF1 gene was found to be 100% conserved in 92% of the isolates studied, Crf proteins were expressed in 98% of the strains. In addition, we highlighted the role of Crf proteins in fungal growth, using a deletion mutant for CRF1 gene, for which a growth decrease of 23.6% was observed after 48 h. It was demonstrated that anti-Crf antibodies neutralized the enzymatic activity of recombinant Crf protein, and delayed fungal growth by 12.3% in vitro when added to spores. In a neutropenic rat model of invasive pulmonary aspergillosis, anti-Crf antibodies elicited a significant recruitment of neutrophils, macrophages and T CD4 lymphocytes but it was not correlated with a decrease of fungal burden in lungs and improvement in survival. Overall, our study highlighted the potential relevance of targeting Crf cell wall protein (CWP) with therapeutic antibodies.

Challenging Investigation of a Norovirus Foodborne Disease Outbreak During a Military Deployment in Central African Republic

In January 2016, a large-scale outbreak of acute gastroenteritis was reported among French armed forces deployed in the Central African Republic. Challenging investigations, conducted from France, made it possible to identify a norovirus genogroup II in both stool and food samples, confirming a norovirus foodborne disease outbreak. Infected food handler management is discussed.

Discordance in the minimal inhibitory concentrations of ertapenem for Enterobacter cloacae: Vitek 2 system versus Etest and agar dilution methods

Our objective was to compare the ertapenem minimal inhibitory concentrations (MICs) for Enterobacter cloacae isolates categorized intermediate or resistant to ertapenem when measured with the Vitek 2 system, with the MICs for these isolates when measured by two methods performed in agar medium: the Etest and agar plate dilution method (APDM). Overall, 50 E. cloacae isolates were included in the study. The mean MIC of ertapenem was 2.92±1.77μg/ml according to the Vitek 2 system, 0.94±0.84μg/ml according to the Etest strips, and 0.93±0.62μg/ml according to the APDM. Furthermore, the MICs determined by the Vitek 2 system were higher than the MICs determined by the two other methods for 96% of strains. Lastly, according to the Etest strips and APDM, 42% of E. cloacae were susceptible to ertapenem. No carbapenemase was identified by the screening method used. Using the Vitek 2 system to determine ertapenem MICs for E. cloacae can have potential consequences in terms of additional carbapenemase-detecting tests and antimicrobial therapy. It would be interesting to determine if the Vitek 2 system is more effective for the detection of carbapenemase producers with low-level carbapenem resistance than the two methods performed in agar medium.