Arnaud Riat

Accelerated photoactivated chromophore for keratitis-corneal collagen cross-linking as a first-line and sole treatment in early fungal keratitis.

PURPOSE To report the use of accelerated photoactivated chromophore for keratitis-corneal collagen cross-linking (PACK-CXL) as a first-line treatment in a patient with an atypical fungal keratitis. METHODS Case report and literature review. RESULTS A patient who presented with a painful peripheral corneal infiltrate underwent PACK-CXL with a local limited abrasion and accelerated ultraviolet-A irradiation at 365 μm and 9 mW/cm² for 10 minutes. Cultures grew Aureobasidium pullulans. The corneal epithelium closed completely within 3 days and the infiltrate was completely eradicated without administration of antibiotics. CONCLUSIONS Accelerated PACK-CXL was successfully used as a first-line and sole treatment in a case of early fungal keratitis caused by Aureobasidium pullulans. Further characterization of the antifungal effect of PACK-CXL is needed in prospective studies.

Confident identification of filamentous fungi by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry without subculture-based sample preparation

The identification of moulds by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDITOF MS) has been evaluated repeatedly for use in clinical diagnostic settings. However, recommended protocols are based on the analysis of time-consuming subcultures rather than primary growth obtained on solid isolation media. In order to compare the identification performance of MALDITOF MS applied to primary colonies (protocol A) versus subculture samples (protocol B), 111 reference specimens representing 30 clinically relevant species were analyzed. Each of these species was identified, at least once, by internal transcribed spacer (ITS) sequence analysis, which was considered the gold standard in this study (Table 1). In addition, each of the 111 strains was identified by phenotype testing. In protocol A, primary growth on Sabouraud agar (Difco Sabouraud Agar, Modified) after 24 to 72 h of incubation (time required for the first visible mycelium growth) was collected carefully, avoiding agar, by means of a wooden toothpick. The biomass was deposited on an unpolished target plate, air-dried, and overlaid with 1 ml alpha-cyano-4-hydroxycinnamic acid. In protocol B, and in accordance with the Bruker protocol, the filamentous fungi were inoculated in 8 ml of Sabouraud liquid broth (Difco Sabouraud Maltose Broth), which was rotated overnight at room temperature. The sediments of overnight subcultures were washed thoroughly, extracted with acetonitrile–formic acid, and then 1 ml of supernatant was placed onto an unpolished target plate and processed further, as above.

Ground Steel Target Plates in Combination with Direct Transfer of Clinical Candida Isolates Improves Frequencies of Species-Level Identification by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry in Comparison with Polished Steel Target Plates

MALDI-TOF MS identification of yeast isolates is fast and reliable, but the optimal workflow is debated (1, 2).…Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identification (ID) of Candida yeast isolates is fast and reliable, but the optimal workflow is debated ([1][1], [2][2]). Two different steel target plates are available for the Microflex system (Bruker

Fast identification of dermatophytes by MALDI-TOF/MS using direct transfer of fungal cells on ground steel target plates

Dermatophytes cause human infections limited to keratinised tissues. We showed that the direct transfer method allows reliable identification of non‐dermatophytes mould and yeast by MALDI‐TOF/MS. We aimed at assessing whether the direct transfer method can be used for dermatophytes and whether an own mass spectra library would be superior to the Bruker library. We used the Bruker Biotyper to build a dermatophyte mass spectra library and assessed its performance by 1/testing a panel of mass spectrum produced with strains genotypically identified and, 2/comparing MALDI‐TOF/MS identification to morphology‐based methods. Identification of dermatophytes using the Bruker library is poor. Our library provided 97% concordance between ITS sequencing and MALDI‐TOF/MS analysis with a panel of 1104 spectra corresponding to 276 strains. Direct transfer method using unpolished target plates allowed proper identification of 85% of dermatophytes clinical isolates most of which were common dermatophytes. A homemade dermatophyte MSP library is a prerequisite for accurate identification of species absent in the Bruker library but it also improves identification of species already listed in the database. The direct deposit method can be used to identify the most commonly found dermatophytes such as T. rubrum and T. interdigitale/mentagrophytes by MALDI‐TOF/MS.