ABSTRACT
In this study MALDI-TOF MS was evaluated in the identification of anaerobic bacteria comparing it with Rapid ID 32A system. Discrepancies were solved by 16S r-RNA gene sequencing. At the species level MALDI-TOF MS identified 94.82% and Rapid ID 32A 86.67%, showing the superiority of MALDI-TOF MS to conventional methods.
Subject(s)
Bacteria, Anaerobic/classification , Bacteria, Anaerobic/isolation & purification , Bacterial Infections/diagnosis , Bacterial Infections/microbiology , Bacteriological Techniques/methods , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Bacteria, Anaerobic/chemistry , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Humans , RNA, Ribosomal, 16S/genetics , Sensitivity and Specificity , Sequence Analysis, DNAABSTRACT
Bacteria that produce extended-spectrum ß-lactamases (ESBLs) are an increasing healthcare problem and their rapid detection is a challenge that must be overcome in order to optimize antimicrobial treatment and patient care. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has been used to determine resistance to ß-lactams, including carbapenems in Enterobacteriaceae, but the methodology has not been fully validated as it remains time-consuming. We aimed to assess whether MALDI-TOF can be used to detect ESBL-producing Enterobacteriaceae from positive blood culture bottles in clinical practice. In the assay, 141 blood cultures were tested, 13 of them were real bacteraemias and 128 corresponded to blood culture bottles seeded with bacterial clinical isolates. Bacteraemias were analysed by MALDI-TOF after a positive growth result and the 128 remaining blood cultures 24 h after the bacterial seeding. ß-lactamase activity was determined through the profile of peaks associated with the antibiotics cefotaxime and ceftazidime and its hydrolyzed forms. Clavulanic acid was added to rule out the presence of non-ESBL mechanisms. Overall data show a 99% (103 out of 104) sensitivity in detecting ESBL in positive blood cultures. Data were obtained in 90 min (maximum 150 min). The proposed methodology has a great impact on the early detection of ESBL-producing Enterobacteriaceae from positive blood cultures, being a rapid and efficient method and allowing early administration of an appropriate antibiotic therapy.