Dynamic full-field optical coherence tomography for live-cell imaging and growth-phase monitoring in Aspergillus fumigatus.

Introduction: The diagnosis of cutaneous manifestations of deep mycoses relies on both histopathological and direct examinations. Yet, the current diagnostic criteria cannot prevent missed cases, including invasive aspergillosis, which requires the development of a novel diagnostic approach and imaging tools. We recently introduced the use of dynamic full-field optical coherence tomography (D-FF-OCT) in fungal diagnostics with a definition approaching that of conventional microscopy and the ability to return metabolic information regarding different fungal species. The present work focuses on subcellular dynamics and live-cell imaging of Aspergillus fumigatus with D-FF-OCT to follow the fungal growth stages. Methods: The A. fumigatus ATCC 204305 quality-control strain was used for all imaging experiments, following incubation times varying between 24 and 72 h at 30°C in a humidified chamber on Sabouraud dextrose agar. Fungal growth was subsequently monitored with D-FF-OCT for up to 5 h at room temperature and following the pharmacological stress of either voriconazole, amphotericin B, or caspofungin gradient concentration. Results: D-FF-OCT images allow not only the visualization of intracellular trafficking of vacuoles but also an evolving dynamic segmentation of conidiophores depending on the chronological development and aging of the hyphae or the effect of antifungal treatment. The same applies to conidial heads, with the most intense D-FF-OCT signal coming from vesicles, revealing a changing dynamic within a few hours only, as well as complete extinction following subsequent drying of the Sabouraud dextrose agar. Discussion: These results provide additional data on the ability of D-FF-OCT to monitor some of the main life cycle processes, dynamics, and intracellular trafficking of vacuoles in A. fumigatus, with or without the effect of pharmacological stress. Such complementary metabolic information could help both clinicians and microbiologists in either mechanistic studies toward experimental mycology or the development of a potential D-FF-OCT-guided diagnosis of superficial fungal infections.

[Capnocytophaga canimorsus: atypical septicemic meningitis, approach to microbiological diagnosis and therapeutic impact]. / Capnocytophaga canimorsus : méningite septicémique atypique, démarche du diagnostic microbiologique et impact thérapeutique.

Meningitis and septicaemia due to Capnocytophaga canimorsus are extremely rare and described as emerging zoonoses because of their low incidence and prevalence, but also because of the challenges in bacterial identification, thus, the real number of cases is probably underestimated. We report the case of a 61-year-old man, with a history a chronic alcoholism, who developed, following a recent dog bite, meningitis with normoglycorachia and concomitant sepsis, and had a favorable outcome after intravenous probabilistic antibiotherapy combining ceftazidime and metronidazole. This association aimed to cover the risks represented by Pseudomonas spp and anaerobic bacteria, once the microorganisms commonly associated with meningitis were excluded using molecular biology tools. In addition to the unusual biological results (normoglycorachia and bacterial morphology after Gram staining), we present the biological diagnostic approach (molecular, biochemical and physical tools successively used to lead, by exclusion and confirmation, to this diagnosis), closely linked to the clinical expertise. This is, to our knowledge, the first described case of meningitis with normoglycorachia and septicaemia due to Capnocytophaga canimorsus successfully treated with ceftazidime and confirmed by identification by MALDI-TOF mass spectrometry.

Detection of different classes of carbapenemases: Adaptation and assessment of a phenotypic method applied to Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii, and proposal of a new algorithm.

A new phenotypic method for detecting carbapenemases has been adapted (assembling of two MAST® kits, including one that contains faropenem to which a temocillin disk has been added) then assessed using 101 bacterial strains (Enterobacteriaceae with assays on Pseudomonas aeruginosa and Acinetobacter baumannii) including 62 which produce genetically identified carbapenemases. Concerning Carbapenemase-Producing Enterobacteriaceae (CPE), there is 100% sensitivity for Klebsiella pneumoniae carbapenemase (KPC, Ambler class A) and OXA-48 (Ambler class D), and 91% for metallo-beta-lactamase (MBL, Ambler class B), with a 97% sensitivity for all carbapenemases, with a specificity of 100%. The test is also efficient for detecting Pseudomonas aeruginosa carbapenemases (sensitivity between 82 and 100% and 100% specificity). The major innovation is the combined use of faropenem and temocillin for reliable detection (excellent performance with 100% sensitivity and specificity) of OXA-48. This study has led to the development of a new algorithm to detect the different classes of carbapenemases, for first-line diagnosis, by combining this modified MAST® test with immunochromatographic methods and molecular biology techniques.