Early diagnosis of severe infections requires of a rapid and reliable diagnosis to initiate appropriate treatment, while avoiding unnecessary antimicrobial use and reducing associated morbidities and healthcare costs. It is a fact that conventional methods usually require more than 24–48 h to culture and profile bacterial species. Mass spectrometry (MS) is an analytical technique that has emerged as a powerful tool in clinical microbiology for identifying peptides and proteins, which makes it a promising tool for microbial identification. Matrix assisted laser desorption ionization–time of flight MS (MALDI–TOF MS) offers a cost- and time-effective alternative to conventional methods, such as bacterial culture and even 16S rRNA gene sequencing, for identifying viruses, bacteria and fungi and detecting virulence factors and mechanisms of resistance. This review provides an overview of the potential applications and perspectives of MS in clinical microbiology laboratories and proposes its use as a first-line method for microbial identification and diagnosis.

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Nosocomial infections caused by multidrug-resistant and carbapenem-resistant Pseudomonas putida isolates have been reported occasionally in severely ill or immunocompromised patients. Here we report the microbiological characteristics of what are believed to be the two first carbapenem-resistant VIM metallo-b-lactamase (MBL)-producing P. putida strains in Spain, which were isolated from patients at the University Hospital Complex of Santiago de Compostela. Both patients were immunocompromised with severe underlying diseases and had been hospitalized for more than 15 days. One of them had previously been treated with a broadspectrum therapy. Antimicrobial susceptibility testing showed that both strains were resistant to piperacillin/tazobactam, ceftazidime, cefepime, imipenem, meropenem, gentamicin, tobramycin, aztreonam, trimethoprim/sulfamethoxazole and ciprofloxacin, but sensitive to amikacin and colistin. For both isolates PCR and sequencing was positive for the bla VIM-2 gene. Fingerprinting analysis revealed these were two different strains. One patient recovered clinically and one died; no direct link could be established between the isolation of P. putida and death. Our data expose the emergence of multidrug-resistant P. putida VIM-2 MBL, probably arising by independent horizontal transfer of resistance genes. So, although P. putida is not frequently isolated, it may survive easily in the hospital setting and occasionally cause difficult-to-treat nosocomial infections in severely ill patients.

The risk of a rapid dissemination and the persistence of these multidrug-resistant strains through the time determine the need to implement routine procedures for metallo-beta-lactamase detection and measures for prevention of the spread of these microorganisms. The combined use of MALDI-TOF for species identification and DiversiLab System for clonal strain typing may be a useful tool for fast and accurate management of nosocomial outbreaks. The potential clinical utility of fosfomycin in this matter should be considered in future studies.

Trichosporon asahii has been recognized as an emerging opportunistic agent for invasive infections, mainly in immunocompromised patients. Urinary tract infections by this pathogen may also occur, especially in patients with urinary obstruction or those undergoing vesical catheterization and antibiotic treatment. Many outbreaks of Trichosporon spp. have been detected after urinary catheter manipulations. We report the molecular-epidemiological characterization of T. asahii in our institution using the DiversiLab system for the molecular strain typing and compare three different methods for susceptibility testing. Our results present T. asahii as an emergent pathogen in elderly patients with urinary drainage devices that can be adequately treated with triazoles, with voriconazole being the most active. Broth dilution and Vitek 2 had good concordance, while Etest showed more discrepancies. In addition, the DiversiLab system for clonal strain typing may be a useful tool for fast and accurate management of nosocomial outbreaks.