الفهرس 
Aim Of The StudyOnly 14 pages are availabe for public view
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Abstract
In the clinical diagnostic microbiology laboratory, the identification of fungal isolates is currently mainly based on phenotypic characteristics, such as growth on different media, colony morphology, Gram stain, and various biochemical reactions.
These techniques allow the identification of most fungal isolates with great accuracy, but they are costly and time-consuming. The matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) technique can be used to generate protein fingerprint signatures from whole candidal cells. By comparing these fingerprints to a data-base of reference spectra by the use of various algorithms, Candida can be rapidly identified.
During the analysis process, proteins are ionized without fragmentation by the coordinated action of the laser and the organic acids of the matrix and separated on the basis of their mass-to-charge ratio, a process which results in a characteristic mass spectral profile.
In clinical microbiology laboratory, we prospectively assessed the Performance of MALDI-TOF MS for the identification of Candida species isolated from clinical samples.
Fifty candidal samples from different origins as blood, urine, sputum and pus were isolated by culture on Sabouraud’s dextrose agar and after overnight incubation pure colonies were isolated and analyzed by MALDI-TOF MS by mixing in a large quantity of matrix which consists of Cyano-hydroycinamic acid (CHCA) using MALDI –TOF slide and by using E. coli ATCC 8739 strain as calibrator and control. Then samples were analyzed by BIGGY agar as a differential conventional method. The results revealed the following:
• For 50 isolates, C. tropicalis was the most common species as it was isolated from 30 cases (60%), C. albicans was isolated in 15 cases (30%), C. parapsilosis was isolated in 4 cases (8%) and Kodamaea Ohmeri was isolated from one case (2%).
• Results by MALDI-TOF MS were considered standard, agreement with results obtained by BIGGY agar was about 87%, and this results are statistically good.
• BIGGY agar results in identification of candidal infections were satisfactory, it can be used in absence of other reference techniques.
• A progressive shift from C. albicans to non-albicans Candida spp. was observed in most parts of the world, which is probably related to the increased exposure to azoles which minimized the sensitive C. albicans colonization rate. This favored the resistant C. tropicalis, C. glabrata and C. krusi infections.
• In addition to morphological, biochemical microbiological testing analysis along with molecular identification at the DNA and mRNA levels,MALDI-TOF MS is now becoming a third diagnostic pillar with strong discriminating power.
• A major thrust to use MALDI comes from its time saving benefit: the 24–48 h needed with culture-based methodologies is cut down to a few minutes.
• Antifungal sensitivity test by Vitek2 provides useful information sooner than conventional methods, it can be successfully adapted to clinical mycology, especially in those institutions that have acquired MALDI-TOF MS technology for species-level identification purposes, this will be of great practical value with effort and time conserve, So it is recommended to use Vitek2 in antifungal susceptibility testing.
With advantages of MALDI-TOF MS as reduced time span, inoculants volume organism and no prior knowledge about the organism,this gives the clinical advantage of accelerating microbial diagnosis to speed up specific antibiotic and supportive treatment. These advantages can overcome disadvantages of conventional methods which still depend on conventional microbiology techniques and BIGGY agar, as it needs prior knowledge about the organism.