Evaluation of new colorimetric vitek 2 yeast identification card by use of different source media

Global Epidemiology of Invasive Infections by Uncommon Candida Species: A Systematic Review

Emerging and uncommon Candida species have been reported as an increasing cause of invasive Candida infections (ICI). We aim to systematize the global epidemiology associated with emergent uncommon Candida species responsible for invasive infections in adult patients. A systematic review (from 1 January 2001 to 28 February 2023) regarding epidemiological, clinical, and microbiological data associated to invasive Candida infections by uncommon Candida spp. were collected. In total, 1567 publications were identified, and 36 were selected according to inclusion criteria (45 cases). The chosen studies covered: C. auris (n = 21), C. haemulonii (n = 6), C. fermentati (n = 4), C. kefyr (n = 4), C. norvegensis (n = 3), C. nivariensis (n = 3), C. bracarensis (n = 1), C. duobushaemulonii (n = 1), C. blankii (n = 1), and C. khanbhai (n = 1). Over the recent years, there has been an increase in the number of invasive infections caused by uncommon Candida spp. Asia and Europe are the continents with the most reported cases. The challenges in strain identification and antifungal susceptibility interpretation were significant. The absence of clinical breakpoints for the susceptibility profile determination for uncommon Candida spp. makes interpretation and treatment options a clinical challenge. It is crucial that we focus on new and accessible microbiology techniques to make fast and accurate diagnostics and treatments.

Establish intelligent detection system to evaluate the sugar smoking of chicken thighs

The objective of this study was to establish a standardized color detection method to achieve low-cost, rapid, nonintrusive and accurate characterization of the color change of smoked chicken thighs during the smoking process. This study was based on machine vision technology using the Mean algorithm, K-means algorithm and K-means algorithm + image noise reduction algorithm to establish 3 colorimetric cards for the color of sugar-smoked chicken thighs. The accuracy of the 3 colorimetric cards was verified by the K-medoids algorithm and sensory analysis, respectively. Results showed that all 3 colorimetric cards had significant color gradient changes. From the K-medoids algorithm, the accuracy of the colorimetric card produced by the Mean algorithm, K-means algorithm and K-means algorithm + image noise reduction algorithm was 87.2, 95.1, and 96.7%, respectively. Meanwhile, the verification results of the sensory analysis showed that the accuracy of the Mean algorithm, K-means algorithm and K-means algorithm + image noise reduction algorithm colorimetric card was 69.4, 80.9, and 79.2%, respectively. A comparative analysis found that the colorimetric cards produced by the K-means algorithm and K-means algorithm + image noise reduction have excellent accuracy. These 2 colorimetric cards could become a suitable method for rapid, low-cost, and accurate online color monitoring of smoked chicken.

The Inhibitory Effect of Human Beta-defensin-3 on Candida Glabrata Isolated from Patients with Candidiasis

Candida glabrata is a common non-albicans Candida species found in patients with candidiasis and it sometimes develops antifungal resistance. Human beta-defensin-3 (hBD-3) is an antimicrobial peptide of immune system active against various types of microbes including Candida spp. This study investigated antifungal activity of hBD-3 and its synergistic effect with a first-line antifungal agent on C. glabrata clinical isolates. Candida spp. were characterised in patients with candidiasis. The antifungal activities of hBD-3 and fluconazole against C. glabrata were evaluated using Broth microdilution assay. The synergistic activity of these two agents was determined by checkerboard microdilution and time-killing assays. The cytotoxicity of hBD-3 was evaluated using LDH-cytotoxicity colorimetric assay. Of 307 episodes from 254 patients diagnosed with candidiasis, C. glabrata was found in 21 clinical isolates. Antifungal susceptibility tests of C. glabrata were performed, fluconazole demonstrated an inhibitory effect at concentrations of 0.25-8 μg/ml, but one antifungal resistant strain was identified (>64 μg/ml). hBD-3 showed an inhibitory effect against all selected strains at concentrations of 50-75 μg/ml and exhibited a synergistic effect with fluconazole at the fractional inhibitory concentration index (FICI) of 0.25-0.50. A concentration of 25 μg/ml of hBD-3 alone showed no cytotoxicity but synergistic activity was seen with fluconazole. In conclusion, hBD-3 has antifungal activity against C. glabrata and synergistic effects with fluconazole at concentrations that alone, have no cytotoxicity. hBD-3 could be used as an adjunctive therapy with first-line antifungal agents for patients with C. glabrata infection particularly those infected with fluconazole-resistant strains.

Central line bundle including split-septum device and single-use prefilled flushing syringes to prevent port-associated bloodstream infections: a cost and resource-utilization analysis

Background

Central line bundle programs were found to be effective in decreasing central line-associated bloodstream infection rates in pediatric cancer patients with ports. However, cost-effectiveness studies of central line bundle programs in pediatric cancer patients are limited, and most available data are from intensive care unit or adult studies.

Methods

In this cross-sectional study spanning 6 years, comprehensive assessment of total health care costs attributable to CLABSI’s associated with ports between two periods.

Results

This cross-sectional study was carried out in the pediatric hematology-oncology ward of Dr. Behçet Uz Children’s Hospital from 1 August November 2011 to 31 July 2017. The CLABSI rates decreased significantly from 8.31 CLABSIs to 3.04 per 1000 central line days (p < 0.001). In the pre-bundle period, total attributable costs spent for of patients with CLABSI were $130,661, and in the bundle period, total attributable costs spent for patients with CLABSI were $116,579. Within bundle implantation, 71 potential CLABSI were prevented, which saved an additional $208,977.

Conclusion

Our study shows that central line bundles decreases not only the CLABSI rate but also decreases attributable costs due to CLABSI. Expenses spent for bundle elements, were covered by savings by preventing CLABSI with higher costs.

Infections in Pediatric Burn Patients: An Analysis of One Hundred Eighty-One Patients

Background: Infectious complications are one of the most life-threatening complications and result in substantial mortality and morbidity in children who have been burned. The goal of the study is to assess the risk factors for sepsis in pediatric burn patients in a referral hospital. Methods: This study was performed at the Pediatric Burn Unit of Ankara Child Health and Diseases Hematology Oncology Training and Research Hospital during the period between January 2014 and June 2017. The patients were evaluated for age, sex, burn etiology, burned body surface area (BSA), the presence of inhalation injury, sepsis, positive cultures, the micro-organisms cultured samples, and septic focus. Results: A total of 181 patients were included in the study. The most common cause of burns was scalds in 120 patients (66.3%). Forty-one patients (22.7%) developed health-care-associated infection and sepsis. Gram-negative micro-organisms were isolated in 40 (97.6%) patients (Acinetobacter spp., Pseudomonas aeruginosa, Klebsiella pneumonia) with sepsis. Carbapenem resistance was detected in 31 (93.8%) of 40 patients. Mortality was observed in 11 patients (6.1%) in the group with sepsis. Burn surface area, burn depth, C-reactive protein (CRP) values, mortality, Garcés index, and Baux index were higher in the group with sepsis (p < 0.05). Multiple regression analysis revealed that mechanism of injury (flame), burned BSA ≥25%, C-reactive protein ≥6 mg/dL (area under the curve [AUC]: 0.76 p < 0.001 and AUC: 0.90, p < 0.001, respectively) at admission were independent parameters for development of sepsis in pediatric burn patients. Conclusion: Multi-drug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii were important agents of blood stream infection in burned children. Burned BSA ≥25% and CRP ≥6 mg/dL were risk factors for developing sepsis in pediatric burn patients.

Central line bundle for prevention of central line-associated bloodstream infection for totally implantable venous access devices (ports) in pediatric cancer patients

OBJECTIVE

The clinical impact of central line bundle programs for central line-associated bloodstream infections has been well demonstrated in intensive care units. However, the experience of central line bundle programs in totally implantable venous access devices (ports) in pediatric-hematology patients was limited.

METHODS

A retrospective study was designed to compare and evaluate the clinical impact of implementing a central line bundle for a 2-year 5-month period, including 10 months of prebundle period, 11 months of central line bundle (that includes needleless split-septum devices), and finally 8 months of central line bundle period in which single-use prefilled flushing devices were added to the previous central line bundle.

RESULTS

During the prebundle period, the rate of 14.5 central line-associated bloodstream infections per 1000 CL-days had decreased to 5.49 CLABSIs per 1000 CL-days in the first bundle period. The incidence rate ratio with these two groups was 0.379, indicating a relative risk reduction of 62% ( p = 0.005). By the addition of single-use prefilled flushing devices to the first bundle program, the central line-associated bloodstream infection rate decreased to 2.63 per 1000 CL-days. Port removal rate due to central line-associated bloodstream infections was 0.46 per 1000 catheter days in the bundle period, which was significantly lower than in the prebundle period in which port removal rate was 4.5 per 1000 catheter days ( p < 0.001).

CONCLUSION

Central line bundle programs were found to be effective in decreasing central line-associated bloodstream infection rates, improving patients' quality of life by preventing ports removal due in pediatric cancer patients.

Identification and antifungal susceptibility of Candida species isolated from the urine of patients in a university hospital in Brazil

The aim of this study was to identify Candida spp. isolated from candiduria episodes at a tertiary hospital in the Midwest region of Brazil, and to determine their susceptibility profiles to antifungal compounds. From May 2011 to April 2012, Candida spp. isolated from 106 adult patients with candiduria admitted to the University Hospital of the Federal University of Mato Grosso do Sul were evaluated. Both, species identification and susceptibility testing with fluconazole-FLC, voriconazole-VRC, and amphotericin B-AmB were carried out using the Vitek 2. To discriminate species of the C. parapsilosis complex, a RAPD-PCR technique using the RPO2 primer was performed. From the total of 106 isolates, 42 (39.6%) C. albicans and 64 (60.4%) Candida non-albicans (CNA) - 33 C. tropicalis, 18 C. glabrata, 5 C. krusei, 4 C. parapsilosis sensu stricto, 2 C. kefyr, 1 C. lusitaniae, and 1 C. guilliermondii were identified. All isolates were susceptible to AmB and VRC, whereas all C. glabrata isolates presented either resistance (5.6%) or dose-dependent susceptibility (94.4%) to FLC. The study of Candida spp. and their resistance profiles may help in tailoring more efficient therapeutic strategies for candiduria.

Fungal Pathogens in CF Airways: Leave or Treat?

Chronic airway infection plays an essential role in the progress of cystic fibrosis (CF) lung disease. In the past decades, mainly bacterial pathogens, such as Pseudomonas aeruginosa, have been the focus of researchers and clinicians. However, fungi are frequently detected in CF airways and there is an increasing body of evidence that fungal pathogens might play a role in CF lung disease. Several studies have shown an association of fungi, particularly Aspergillus fumigatus and Candida albicans, with the course of lung disease in CF patients. Mechanistically, in vitro and in vivo studies suggest that an impaired immune response to fungal pathogens in CF airways renders them more susceptible to fungi. However, it remains elusive whether fungi are actively involved in CF lung disease pathologies or whether they rather reflect a dysregulated airway colonization and act as microbial bystanders. A key issue for dissecting the role of fungi in CF lung disease is the distinction of dynamic fungal-host interaction entities, namely colonization, sensitization or infection. This review summarizes key findings on pathophysiological mechanisms and the clinical impact of fungi in CF lung disease.

Breakthrough fungemia due to Candida fermentati with fks1p mutation under micafungin treatment in a cord blood transplant recipient

The prophylactic use of antifungal drugs in allogeneic hematopoietic cell transplant recipients has revealed that the rate of non-albicans candidemia has increased. We herein report the case of a patient with adult T-cell leukemia who developed candidemia due to Candida fermentati during micafungin treatment after cord blood transplantation. The isolate was identified on day 47 by sequencing of the internal transcribed spacer region of the ribosomal RNA gene. The sequencing of the hot spot region of fks1p of isolate revealed naturally occurring amino acid substitutions, which conferred reduced echinocandin susceptibility. This case highlights that breakthrough candidemia due to C. fermentati occurred in a patient receiving micafungin treatment.

Burn-associated bloodstream infections in pediatric burn patients: Time distribution of etiologic agents

BACKGROUND

Infections are the leading cause of morbidity and mortality in patients with burns in burn units. Bloodstream infections (BSIs) in patients with burns may result from burn wound infection, use of invasive devices such as central venous catheters, and translocation of the gastrointestinal flora.

OBJECTIVE

In this study, we investigated the distribution and antimicrobial drug resistance of causative pathogens in children with burns and the durational changes of microorganisms in the distribution of BSIs in children.

METHODS

This study was conducted at the Pediatric Burn Unit (PBU) of Dr. Behçet Uz Children Research and Training Hospital during the period of November 2008-April 2015. The study subjects were all the patients admitted to the PBU, in whom microorganisms were isolated at least from one of the cultures, including blood and catheter cultures.

RESULTS

Gram-positive bacteria were the most common causative agents of BSI in patients with burns (66.4%), followed by gram-negative bacteria (22.1%) and fungi (11.5%). The median duration of development of BSIs caused by gram-positive bacteria from the time of burn was 5 days (ranging from 2 to 54 days of burn), which was significantly shorter than that of BSIs caused by gram-negative bacteria (12 days) and fungal pathogens (13 days).

CONCLUSION

The etiologic agents of BSIs in children may differ from those in adults. Gram-negative drug-resistant bacteria such as multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii were important agents of BSI in patients with burns, especially in the long term; however, gram-positive bacteria should also be considered while deciding the antimicrobial therapy, especially in the early periods of burn.

Are the Conventional Commercial Yeast Identification Methods Still Helpful in the Era of New Clinical Microbiology Diagnostics? A Meta-Analysis of Their Accuracy

Accurate identification of pathogenic species is important for early appropriate patient management, but growing diversity of infectious species/strains makes the identification of clinical yeasts increasingly difficult. Among conventional methods that are commercially available, the API ID32C, AuxaColor, and Vitek 2 systems are currently the most used systems in routine clinical microbiology. We performed a systematic review and meta-analysis to estimate and to compare the accuracy of the three systems, in order to assess whether they are still of value for the species-level identification of medically relevant yeasts. After adopting rigorous selection criteria, we included 26 published studies involving Candida and non-Candida yeasts that were tested with the API ID32C (674 isolates), AuxaColor (1,740 isolates), and Vitek 2 (2,853 isolates) systems. The random-effects pooled identification ratios at the species level were 0.89 (95% confidence interval [CI], 0.80 to 0.95) for the API ID32C system, 0.89 (95% CI, 0.83 to 0.93) for the AuxaColor system, and 0.93 (95% CI, 0.89 to 0.96) for the Vitek 2 system (P for heterogeneity, 0.255). Overall, the accuracy of studies using phenotypic analysis-based comparison methods was comparable to that of studies using molecular analysis-based comparison methods. Subanalysis of studies conducted on Candida yeasts showed that the Vitek 2 system was significantly more accurate (pooled ratio, 0.94 [95% CI, 0.85 to 0.99]) than the API ID32C system (pooled ratio, 0.84 [95% CI, 0.61 to 0.99]) and the AuxaColor system (pooled ratio, 0.76 [95% CI, 0.67 to 0.84]) with respect to uncommon species (P for heterogeneity, <0.05). Subanalysis of studies conducted on non-Candida yeasts (i.e., Cryptococcus, Rhodotorula, Saccharomyces, and Trichosporon) revealed pooled identification accuracies of ≥98% for the Vitek 2, API ID32C (excluding Cryptococcus), and AuxaColor (only Rhodotorula) systems, with significant low or null levels of heterogeneity (P > 0.05). Nonetheless, clinical microbiologists should reconsider the usefulness of these systems, particularly in light of new diagnostic tools such as matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, which allow for considerably shortened turnaround times and/or avoid the requirement for additional tests for species identity confirmation.

[Evaluation of Vitek 2 for the identification of Candida yeasts]

The aim of this investigation was to evaluate the performance of Vitek 2 YST cards (bioMérieux, Inc., Hazelwood, MO, USA) for the identification of yeasts of the genus Candida. A total of 168 isolates were analyzed and the results were compared to those of the API 20 C AUX (24%) o API ID 32 C (76%) kits (bioMérieux, Marcy L'Etoile, France). Each isolate was grown in chromogenic agar and in corn meal agar (Oxoid, UK) to observe its micromorphology. C. albicans and C. dublininesis were identified by additional biochemical and molecular tests. The agreement observed was 98.3%. Only three isolates were incorrectly identified by Vitek 2: one strain of C .tropicalis and one strain of C. krusei were identified as C. parapsilosis by YST while one strain of C. krusei was identified with low discrimination. The average time for obtaining results was 18.25 h. Vitek 2 is a simple, safe and useful system for the identification of significant Candida species.

Comparative evaluation of two matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems for the identification of clinically significant yeasts

OBJECTIVES

To prospectively evaluate the performance of two matrix-assisted laser desorption/ionization time-of-flight mass spectrometry systems (MALDI-TOF MS) for the identification of clinically significant yeast isolates compared to the VITEK 2 system.

METHODS

One hundred and eighty-eight consecutive yeast isolates were analyzed by Bruker Biotyper and VITEK MS. The results were compared with the conventional VITEK 2 yeast identification system. Discrepant results were resolved by direct sequencing of rDNA.

RESULTS

Accurate identification by VITEK 2, VITEK MS, and Bruker Biotyper MS was 94.1% (177/188), 93.0% (175/188), and 92.6% (174/188), respectively. Three isolates were not identified by VITEK MS, while nine Candida orthopsilosis were misidentified as Candida parapsilosis, as this species is not present in its database. Eleven isolates were not identified or were wrongly identified by Bruker Biotyper and although another 14 were correctly identified, the score was unreliable at <1.7.

CONCLUSION

The overall accuracy of rapid MALDI-TOF MS systems was essentially comparable to that of the conventional VITEK 2 yeast identification system. However, future expansion of the databases may further improve the outcome and accuracy of identification of yeast species.

Misidentification of Candida guilliermondii as C. famata among strains isolated from blood cultures by the VITEK 2 system

Introduction. The aim of this study was to differentiate between Candida famata and Candida guilliermondii correctly by using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and gene sequencing. Methods. Twenty-eight Candida strains from blood cultures that had been identified as C. famata (N = 25), C. famata/C. guilliermondii (N = 2), and C. guilliermondii (N = 1) by the VITEK 2 system using the YST ID card were included. We identified these strains by MALDI-TOF MS and gene sequencing using the 28S rRNA and ITS genes and compared the results with those obtained by the VITEK 2 system. Results. All 28 isolates were finally identified as C. guilliermondii. Sequencing analysis of the 28S rRNA gene showed 99.80%–100% similarity with C. guilliermondii for all 28 strains. The ITS gene sequencing of the strains showed 98.34%–100% homology with C. guilliermondii. By MALDI-TOF, we could correctly identify 21 (75%) of 28 C. guilliermondii isolates. Conclusion. We should suspect misidentification when C. famata is reported by the VITEK 2 system, and we always should keep in mind the possibility of misidentification of any organism when an uncommon species is reported.

Accuracy of species-level identification of yeast isolates from blood cultures from 10 university hospitals in South Korea by use of the matrix-assisted laser desorption ionization-time of flight mass spectrometry-based Vitek MS system

We assessed the accuracy of yeast bloodstream isolate identification performed over a 1-year period at 10 South Korean hospitals, using the matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)-based Vitek MS system. The overall phenotypic misidentification rate was 3.4% (18/533), with considerable variation between hospitals (0.0% to 19.0%), compared to 1.1% (6/533) for the Vitek MS system.

Fungal diagnostics: review of commercially available methods

Fungi and yeasts are critical causes of acute infection. As such, the detection and identification of these organisms are crucial in the diagnosis of affected patient populations. There is a vast array of commercial tests currently available for diagnostic purposes. These vary from traditional culture and biochemical methods to advanced multiparameter molecular tests. Recent technological advances have driven the development of rapid tests which are complementing and in some cases replacing the more traditional methods of detection. Irrespective of the method used the ultimate goal is timely detection of the infectious agent allowing appropriate treatment and improved outcome for the patient.

Assessment of accuracy of identification of pathogenic yeasts in microbiology laboratories in the United kingdom

Rapid, accurate identification of yeast isolates from clinical samples has always been important given their innately variable antifungal susceptibility profiles. Recently, this has become paramount with the proposed introduction of species-specific interpretive breakpoints for MICs obtained in yeast antifungal susceptibility tests (M. A. Pfaller, D. Andes, D. J. Diekema, A. Espinel-Ingroff, D. Sheehan, and CLSI Subcommittee for Antifungal Susceptibility Testing, Drug Resist. Updat. 13:180-195, 2010). Here, we present the results of a 12-month evaluation of the accuracy of identifications that accompany yeast isolates submitted to the Mycology Reference Laboratory (United Kingdom) for either confirmation of identity or susceptibility testing. In total, 1,781 yeast isolates were analyzed, and the robustness of prior identifications obtained in microbiology laboratories throughout the United Kingdom was assessed using a combination of culture on chromogenic agar, morphology on cornmeal agar, and molecular identification by pyrosequencing. Over 40% of isolates (755) were submitted without any suggested identification. Of those isolates with a prior identification, 100 (9.7%) were incorrectly identified. Error rates ranged from 5.2% (for organisms submitted for antifungal susceptibility testing) to 18.2% (for organisms requiring confirmation of identity) and varied in a strictly species-specific manner. At least 50% of identification errors would be likely to affect interpretation of MIC data, with a possible impact on patient management. In addition, 2.3% of submitted cultures were found to contain mixtures of at least two yeast species. The vast majority of mixtures had gone undetected in the referring laboratory and would have impacted the interpretation of antifungal susceptibility profiles and patient management. Some of the more common misidentifications are discussed according to the identification method employed, with suggestions for avoiding such misinterpretations.

Pyrosequencing of a hypervariable region in the internal transcribed spacer 2 to identify clinical yeast isolates

The incidence of invasive fungal infection has increased significantly. A majority of the infections is caused by yeast. Clinically important yeast show species-specific differences in susceptibility to antifungal agents therefore rapid and accurate identification of the pathogen is essential. We aimed to validate pyrosequencing of 40 nucleotides in the internal transcribed spacer 2 (ITS2) for species identification of yeast. Amplification of ITS2 and pyrosequencing of targeted region were performed in 940 clinical isolates of yeast. A local database containing the 40 nucleotide ITS2 sequences of 33 species of medically important yeast was generated using published sequences of type strains. The sequencing results were searched against the local database using the BLAST algorithm to identify the species of yeast. The length of sequences obtained from pyrosequencing averaged between 40-61 nucleotides. Pyrosequencing identified 940 clinical isolates of yeast down to 14 species level, whereby 931 isolates belonged to genus Candida (11 species), four of Saccharomyces cerevisiae, three of Malassezia pachydermatis and two of Rhodotorula mucilaginosa. In addition, intraspecies specific sequence variations in Candida albicans and Candida glabrata were detected. Pyrosequencing of 40 nucleotides in ITS2 is reliable for species identification of yeast. This methodology can contribute to the high quality management of patients with fungal infections.

Misidentification of Candida parapsilosis as C famata in a clinical case of vertebral osteomyelitis

A case of vertebral osteomyelitis involving misidentification of Candida parapsilosis as C famata by the VITEK 2 compact is described. Species-specific primers were used in the polymerase chain reaction to correctly identify the clinical isolate. When uncommon species of Candida are reported using automated systems, heightened clinical suspicion is warranted.

MALDI-TOF mass spectrometry proteomic phenotyping of clinically relevant fungi

Proteomics is particularly suitable for characterising human pathogens with high life cycle complexity, such as fungi. Protein content and expression levels may be affected by growth states and life cycle morphs and correlate to species and strain variation. Identification and typing of fungi by conventional methods are often difficult, time-consuming and frequently, for unusual species, inconclusive. Proteomic phenotypes from MALDI-TOF MS were employed as analytical and typing expression profiling of yeast, yeast-like species and strain variants in order to achieve a microbial proteomics population study. Spectra from 303 clinical isolates were generated and processed by standard pattern matching with a MALDI-TOF Biotyper (MT). Identifications (IDs) were compared to a reference biochemical-based system (Vitek-2) and, when discordant, MT IDs were verified with genotyping IDs, obtained by sequencing the 25-28S rRNA hypervariable D2 region. Spectra were converted into virtual gel-like formats, and hierarchical clustering analysis was performed for 274 Candida profiles to investigate species and strain typing correlation. MT provided 257/303 IDs consistent with Vitek-2 ones. However, amongst 26/303 discordant MT IDs, only 5 appeared "true". No MT identification was achieved for 20/303 isolates for incompleteness of database species variants. Candida spectra clustering agreed with identified species and topology of Candida albicans and Candida parapsilosis specific dendrograms. MT IDs show a high analytical performance and profiling heterogeneity which seems to complement or even outclass existing typing tools. This variability reflects the high biological complexity of yeasts and may be properly exploited to provide epidemiological tracing and infection dispersion patterns.

Enzymatic substrates in microbiology

Enzymatic substrates are powerful tools in biochemistry. They are widely used in microbiology to study metabolic pathways, to monitor metabolism and to detect, enumerate and identify microorganisms. Synthetic enzymatic substrates have been customized for various microbial assays, to detect an expanding range of both new enzymatic activities and target microorganisms. Recent developments in synthetic enzymatic substrates with new spectral, chemical and biochemical properties allow improved detection, enumeration and identification of food-borne microorganisms, clinical pathogens and multi-resistant bacteria in various sample types. In the past 20 years, the range of synthetic enzymatic substrates used in microbiology has been markedly extended supporting the development of new multi-test systems (e.g., Microscan, Vitek 2, Phoenix) and chromogenic culture media. The use of such substrates enables an improvement in time to detection and specificity over conventional tests that employ natural substrates. In the era of intense developments in molecular biology, phenotypic tests involving enzymatic substrates remain useful to analyse both simple and complex samples. Such tests are applicable to diagnostic and research laboratories all over the world.