SummaryBackgroundMatrix-Assisted Laser-Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) has already proven to be a powerful tool for species identification in microbiological laboratories. As adequate and rapid screening methods for antibiotic resistance are crucially needed, the present study investigated the discrimination potential of MALDI-TOF MS among extended-spectrum-beta-lactamase (ESBL) or metallo-beta-lactamases- (MBL) producing and the nonproducing strains of Escherichia coli (n=19), Klebsiella pneumoniae (n=19), and Pseudomonas aeruginosa (n=38), respectively.Material/MethodsWe used a MALDI-TOF MS protocol, usually applied for species identification, in order to integrate a screening method for beta-lactamases into the routine species identification workflow. The acquired spectra were analyzed by visual inspection, statistical similarity analysis and support vector machine (SVM) classification algorithms.ResultsNeither visual inspection nor mathematical similarity analysis allowed discrimination between spectra of beta-lactamase-producing and the nonproducing strains, but classification within a species by SVM-based algorithms could achieve a correct classification rate of up to 70%.ConclusionsThis shows that MALDI-TOF MS has definite potential to discriminate antibiotic-resistant strains due to ESBL and MBL production from nonproducing strains, but this performance is not yet sufficiently reliable for routine microbiological diagnostics.
Discrimination of Enterobacteriaceae and Non-fermenting Gram Negative Bacilli by MALDI-TOF Mass SpectrometryMatrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) has proven to be an effective identification tool in medical microbiology. Discrimination to subspecies or serovar level has been found to be challenging using commercially available identification software. By forming our own reference database and using alternative analysis methods, we could reliably identify all implemented Enterobacteriaceae and non-fermenting gram negative bacilli by MALDI-TOF MS and even succeeded to distinguish Shigella sonnei from Escherichia coli (E. coli) and Salmonella enterica spp. enterica serovar Enteritidis from Salmonella enterica spp. enterica serovar Typhimurium. Furthermore, the method showed the ability to separate Enterohemorrhagic E. coli (EHEC) and Enteropathogenic E. coli (EPEC) from non-enteropathogenic E. coli.
Spinal and cerebellar hemangioblastomas are common in von Hippel-Lindau disease (vHLD) and usually treated surgically. Multifocal presence and surgically not amenable locations are issues that require a combined microsurgical and radiosurgical approach to control complex cases.We would like to present the case of a 37-year-old male patient who was diagnosed vHLD with multiple spinal and one infratentorial hemangioblastomas and holocord syrinx formation of the whole spinal cord. Combined microsurgical approaches to two spinal lesions and the cerebellar lesion followed by external beam radiotherapy of the posterior fossa and the whole spinal axis stabilized tumor growth of the asymptomatic lesions, while no recurrent tumors were detected at the site of surgery. A clinical deterioration connected to early postoperative deficits stabilized to a moderate gait ataxia. The follow-up after radiotherapy covered 60 months.A combination of microsurgery and radiosurgery for the surgically not amenable lesions is an adequate treatment regimen to stabilize tumor growth and clinical symptoms of multifocal spinal hemangioblastomas in vHLD, though the therapy should be limited to symptomatic or growing lesions.
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