Routine use of a protease zymogen-based colorimetric assay for the detection of Beta-glucan and its role in clinical practice.

The detection of Aspergillus antigen (galactomannan) is considered a reliable marker for the diagnosis of invasive aspergillosis (IA), yet the sensibility and specificity of the assays commonly employed in routine are not optimal. The aim of the present study was to investigate whether the detection of another panfungal antigen, the (1,3)-b-D-glucan could have an auxiliary role in the identification of patients with IA. The study was carried out on 63 sera belonging to patients who had been screened for galactomannan, according to the clinical suspect of IA. Our data show that the positive galactomannan results were not confirmed by positive (1,3)-b-D-glucan results in patients receiving therapy with beta-lactam antibiotics associated with tazobactam, whereas in all the other cases, with the exception of four, the results of the (1,3)-b-D-glucan test were confirmatory of the galactomannan results.

MALDI-TOF mass spectrometry and microsatellite markers to evaluate Candida parapsilosis transmission in neonatal intensive care units.

Recent studies on outbreaks of Candida showed an increased incidence of bloodstream infections in neonatal intensive care units (NICUs) caused by C. parapsilosis species, highlighting the need for the proper identification and epidemiology of these species. Several systems are available for molecular epidemiological and taxonomic studies of fungal infections: pulsed-field gel electrophoresis (PFGE) represents the gold standard for typing, but is also one of the most lengthy and expensive, while simple sequence repeats (SSRs) is based on polymerase chain reaction (PCR) amplification and is, therefore, faster. Only recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used to identify and type microorganisms involved in nosocomial outbreaks. In our study, 19 strains of C. parapsilosis isolated from the blood cultures of neonates admitted to the University Hospital Federico II were genotyped by the amplification of eight SSR markers and by MALDI-TOF MS. Electrophoretic and spectrometric profile results were compared in order to identify similarities among the isolates and to study microevolutionary changes in the C. parapsilosis population. The discriminatory power and the unweighted pair group method with arithmetic mean (UPGMA) dendrograms generated were compared in order to evaluate the correlation of the groups established by the analysis of the clusters by both methods. Both methods were rapid and effective in highlighting identical strains and studying microevolutionary changes in the population. Our study evidenced that mass spectroscopy is a useful technique not only for the identification but also for monitoring the spread of strains, which is critical to control nosocomial infections.