Rapid identification,fluconazole and micafungin susceptibility testing of Candida species from blood culture by a short incubation method

Bloodstream infections caused by Candida species have increased significantly in the last decade, representing 6 to 13 % of all nosocomial infections [1], [2], [3], [4], [5], [6], [7], [8], [9]. In Latin America, candidemia incidence rates range from 0.74 to 6.0 per 1,000 hospital admissions [10].

Despite all the advances related to the recognition of risk factors and the development of new diagnostic tools, supportive treatment and pharmacotherapy for fungal infections, candidemia are still an important cause of morbidity and mortality in hospitalized patients regardless of immunological status, with rates of mortality close to or above 50 % [1,7,[10], [11], [12], [13]].

The epidemiology of candidemia varies geographically and, although Candida albicans remains the most frequent causal agent in this type of infection, there is concern about the increasing frequency over the years of infections caused by non-albicans Candida species in different parts of the world, as they are more likely to be resistant to the empirical therapies used, which has an important clinical impact [1,7,10,[14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25]]. Studies demonstrated that a delay of adequate pharmacotherapy is correlated with an increase in the mortality rate and, therefore, the rapid identification of species and the determination of their susceptibility profile are essential for the patient outcome[14,17,[26], [27], [28], [29]].

The introduction of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) has been a major technological innovation, revolutionizing clinical microbiology due to its short response time (about 24 hours) [30], [31], [32], [33]. MALDI-TOF is an easy, fast and economical technology that allows the reliable identification of the pathogen in a shorter time than traditional methods [32,34,35]. A survey by Clerc et al. [36] at Lausanne University Hospital showed that pharmacotherapy was adjusted in 35.1 % of the analyzed bacteremia cases and that hospitalization time was reduced by approximately two days when MALDI-TOF MS was implemented in blood culture processing.

Researching rapid protocols to identify and determine the susceptibility profiles of Candida spp. is a current goal in the microbiology field, directly contributing to patient outcomes. Faster diagnostic methods are essential to not only guide pharmacotherapy, improve patient management, and reduce costs and length of stay, especially if the isolated species is resistant to the prescribed drug but also to define institutional empirical therapy, control rates of nosocomial infection in different locations and during an investigation of outbreaks [10,[37], [38], [39], [40]].

This study aimed to develop a rapid, practical and inexpensive method to identify Candida spp. and determine its susceptibility profile to Fluconazole and Micafungin, drugs used worldwide in empirical therapy, from the positive blood culture bottle by a short incubation method.

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