Few studies have systematically standardised and evaluated matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of yeasts from bloodstream infections. This is rapidly becoming pertinent for early identification of yeasts and appropriate antifungal therapy. We used 354 yeast strains identified by polymerase chain reaction (PCR) sequencing for standardisation and 367 blind clinical strains for validation of our MALDI-TOF MS protocols. We also evaluated different sample preparation methods and found the on-plate formic acid extraction method as most cost- and time-efficient. The MALDI-TOF assay correctly identified 98.9% of PCR-sequenced yeasts. Novel main spectrum projections (MSP) were developed for Candida auris, C. viswanathii and Kodamaea ohmeri, which were missing from the Bruker MALDI-TOF MS database. Spectral cut-offs computed by receiver operating characteristics (ROC) analysis showed 99.4% to 100% accuracy at a log score of ≥ 1.70 for C. tropicalis, C. parapsilosis, C. pelliculosa, C. orthopsilosis, C. albicans, C. rugosa, C. guilliermondii, C. lipolytica, C. metapsilosis, C. nivariensis. The differences in the species-specific scores of our standardisation and blind validation strains were not statistically significant, implying the optimal performance of our test protocol. The MSPs of the three new species also were validated. We conclude that MALDI-TOF MS is a rapid, accurate and reliable tool for identification of bloodstream yeasts. With proper standardisation, validation and regular database expansion, its efficiency can be further enhanced.
To assess the prevalence of fungal keratitis, we conducted a retrospective study over 7 years (2005 through 2011) at a tertiary care center in North India. Effort has been made to analyze the disease burden, spectrum of agents and treatment history. The findings were compared with an earlier study at the same center for any change in the epidemiology of the disease. Microbiology records were screened at the Postgraduate Institute of Medical Education and Research, Chandigarh, India, to identify fungal keratitis cases, and available clinical records of those cases were analyzed. Of 2459 clinically suspected fungal keratitis cases, 765 (31 %) cases were direct microscopy confirmed. Of these microscopy-confirmed cases, fungi were isolated in 393 (51.4 %), with Aspergillus spp. ranked top (n = 187, 47.6 %), followed by melanized fungi (n = 86, 21.9 %) and Fusarium spp. (n = 64, 16 %). A male predominance of 78.7 % was noted with a peak in the incidence of fungal keratitis during post-monsoon season (September to November). A delay in diagnosis was significantly associated (p < 0.001) with keratitis cases due to melanized fungi. In comparison with an earlier study, higher isolation of melanized fungi was noted with a widening of the spectrum of agents identified. Thus, fungal keratitis due to Aspergillus spp. remains a serious ocular illness among the active male population in North India with relative rise of keratitis due to melanized fungi. The spectrum of agents causing fungal keratitis has broadened with many rare fungi that are implicated.
A mussel mimetic transdermal patch
was prepared using bacterial
cellulose (BC), a green resource derived from Glucanoacetobacter
xylinus (MTCC7795). To impart the mussel mimetic property,
dopamine (DOPA), a catechol-containing compound, was used to modify
the isolated BC via an amidation reaction between the carboxylated
BC and DOPA, and the end product was successively characterized by 1H NMR and FTIR analysis. The free hydroxyl group of the DOPA
moiety of DOPA-modified BC (BC-DOPA) was utilized to prepare BC-DOPA/rGO/Ag
NPs, a composite film incorporating reduced graphene oxide/silver
nanoparticles (rGO/Ag NPs). The antimicrobial action of the prepared
film was determined against both Gram-positive (Staphylococcus
aureus and Lysinibacillus fusiformis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria.
The bactericidal property of the composite film was determined using
the zone of inhibition (ZOI) method and live–dead assay (DAPI–PI
analysis). The morphological transformation of bacteria upon the application
of the composite film was observed through SEM analysis. The cell
compatibility of the composite film over the NIH 3T3 fibroblast cell
line was assessed through an XTT assay. The in vitro wound-healing
assays over the NIH 3T3 cell line and A549 human lung epithelial cell
line reveal that the presence of rGO and Ag NPs in the composite film
accelerates the wound-healing process.
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