The matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS)-based protein peaks of 4448 and 5302Da are not associated with the presence of Panton-Valentine leukocidin

Szabados, Florian; Becker, Karsten; Eiff, Christof von; Kaase, Martin; Gatermann, Sören

doi:10.1016/j.ijmm.2010.05.005

Cited by 29 publications

(12 citation statements)

References 27 publications

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“…The ribosomal protein S20 RpsT was assigned to the m/z 4,446 signal. Since the precision of linear MALDI-TOF MS measurements is limited, with a potential mass deviation of Ͼ500 ppm with external calibration, RpsT might be identical to the signal at m/z 4,448 that was erroneously postulated to signify the production of the Panton-Valentine leukocidin in ST80 CA-MRSA (11,26).…”

Section: Discussionmentioning

confidence: 99%

Analysis of the Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrum of Staphylococcus aureus Identifies Mutations That Allow Differentiation of the Main Clonal Lineages

et al. 2013

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Staphylococcus aureus causes a wide range of hospital infections. Often, these infections involve epidemic methicillin-resistant S. aureus (MRSA) strains that are transferred by health care workers to patients. In order to detect outbreaks that are caused by epidemic strains, the clinical isolates have to be typed. Multilocus sequence typing (MLST) relies on the sequence analysis of housekeeping genes and is used to allocate the strains to sequence types (ST), which can be grouped into clonal complexes (CC). This method has provided a detailed insight into the population structure of MRSA and methicillin-susceptible S. aureus (MSSA) strains (1). Finer discrimination is achieved by pulsed-field gel electrophoresis (PFGE) and spa typing (2). All of these methods need additional experimentation.In matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), different spectra or signatures of cell extracts (3, 4, 5, 6) or whole cells (7,8,9,10,11,12) could be identified for different strains or groups of strains. An increasing number of laboratories use MALDI-TOF MS for the identification of S. aureus. However, the differences in the signatures of the strains have not been evaluated so far, because the discriminatory threshold of the software used in clinical settings is set up to assign the isolate to a species. To this end, more subtle differences are ignored. Another reason is that, so far, MALDI-TOF MS of whole bacterial cells has been employed in a heuristic manner, and for most species, the identities of the compounds that are detected in the measurements are unknown. Thus, the spectra are not well understood, and the variations in the signatures cannot be interpreted.In principle, two spectra might differ by signal intensity, loss of a signal, or by the shift of a signal. Variations in signal intensity are probably caused by expression differences, which might be directly correlated with culture conditions and, therefore, do not give unambiguous information about a genotype of the strain. The loss of a signal is caused by the total failure to express a protein or peptide, which in turn might indicate a mutation causing a frameshift or stop codon, but might also depend on culture conditions, mutations of regulatory factors, or sample preparation. Thus, there is no clear-cut correlation between the loss of a signal and a genotype. In contrast, peak shifts (i.e., loss of a signal coupled to the appearance of a new signal, both of which are correlated to the same peptide) correspond to point mutations in the genes of the peptides detected in the analysis; the mutation leads to an amino acid exchange that alters the molecular weight of the corresponding gene product.In order to characterize the clonal lineages of S. aureus in the MALDI-TOF MS, this work was aimed at the identification of the peptides that are detected in the spectra and that show mass variations between the clonal complexes of S. aureus. To this end, we analyzed the spectra of 401 S. aureus strains, concentrating on...

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Section: Discussionmentioning

confidence: 99%

Analysis of the Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrum of Staphylococcus aureus Identifies Mutations That Allow Differentiation of the Main Clonal Lineages

et al. 2013

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“…However, acquisition of virulence or resistance factors which are not directly detectable because of their high molecular mass (m/z of Ͼ Ͼ20 kDa) may not be reflected by changes in whole-cell mass spectra. Hence, apparent correlations of mass fingerprints to virulence and resistance need to be thoroughly evaluated, taking into account possible effects of clonality, as some previous erroneous results have already been published (22).…”

Section: Typing By Maldi-tof Ms: What Can We Learn From Pfge?mentioning

confidence: 99%

“…However, based on the points presented above, a consideration of guidelines for the interpretation of MALDI typing data must note that PFGE typing and MALDI typing measure completely different cellular proper- a Adapted from Tenover et al (22). As shown in columns 4 and 5, a peak was considered constant when found in either 80% or 70% of every spectrum for the same species.…”

Section: Typing By Maldi-tof Ms: What Can We Learn From Pfge?mentioning

confidence: 99%

Microbial Typing by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: Do We Need Guidance for Data Interpretation?

et al. 2015

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eThe integration of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in clinical microbiology has revolutionized species identification of bacteria, yeasts, and molds. However, beyond straightforward identification, the method has also been suggested to have the potential for subspecies-level or even type-level epidemiological analyses. This minireview explores MALDI-TOF MS-based typing, which has already been performed on many clinically relevant species. We discuss the limits of the method's resolution and we suggest interpretative criteria allowing valid comparison of strain-specific data. We conclude that guidelines for MALDI-TOF MS-based typing can be developed along the same lines as those used for the interpretation of data from pulsed-field gel electrophoresis (PFGE). Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been integrated into the routine diagnostic workflow of many industrial, pharmaceutical, and medical microbiology laboratories. It has already been thoroughly evaluated for the identification of clinically relevant bacterial species, including anaerobes, Gram-positive rods and cocci, Enterobacteriaceae, and miscellaneous Gram-negative (including nonfermentative) rods, with adequate to excellent results (1, 2).Species identification, however, is only a first step in the diagnostic workflow. The ability to quickly and reliably distinguish or "type" related bacterial isolates is essential for bacterial transmission studies and larger-scale epidemiological surveillance projects. "Conventional" phenotyping methods, such as multiple-susceptibility testing, phage typing, serotyping, biochemical typing, and several others, have been important contributors to our understanding of the epidemiology of community-and health careassociated infections. However, these methods all have practical limitations which render them largely unsuitable for comprehensive bacterial population analyses as well as for scientifically less ambitious but critical infection surveillance. Furthermore, most phenotypic methods have been developed for individual bacterial taxa and are not transferable to other taxa without considerable adaptation.Hence, over the past 2 decades, phenotyping has been largely replaced by "molecular" genotyping. Clonal reproduction by binary fission imprints the evolutionary history of the organism in genotypic markers amenable to analysis by nucleic acid-mediated methods. However, in practice, the ease with which recombination, transfection, and transformation can take place in bacteria necessitates that data from multiple genetic markers are analyzed in defining a "precise" genotype and even then there is no guarantee that an adequate natural taxonomy will be derived. Polyphasic taxonomy currently uses combinations of different phenotypic and/or genotypic data sets to define genera, species, and entities at or below the subspecies level. Still, all these approaches remain time-consuming and relatively...

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“…However, a recent publication calls into question the previous work. Szabados et al claim that protein peaks of 4448 and 5302 Da are not associated with the presence of Panton-Valentine leukocidin [29] .…”

Section: Detection Of Virulence Factorsmentioning

confidence: 99%

Mass spectrometry: a revolution in clinical microbiology?

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Espinal

Dunyach-Rémy

et al. 2012

Clinical Chemistry and Laboratory Medicine (CCLM)

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Recently, different bacteriological laboratory interventions that decrease reporting time have been developed. These promising new broad-based techniques have merit, based on their ability to identify rapidly many bacteria, organisms difficult to grow or newly emerging strains, as well as their capacity to track disease transmission. The benefit of rapid reporting of identification and/or resistance of bacteria can greatly impact patient outcomes, with an improvement in the use of antibiotics, in the reduction of the emergence of multidrug resistant bacteria and in mortality rates. Different techniques revolve around mass spectrometry (MS) technology: matrix-assisted laser desorption ionization time-offlight mass spectrometry (MALDI-TOF MS), PCR combined with electrospray ionization-mass spectrometry (PCR/ESI-MS), iPLEX MassArray system and other new evolutions combining different techniques. This report emphasizes the (r)evolution of these technologies in clinical microbiology.

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The matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS)-based protein peaks of 4448 and 5302Da are not associated with the presence of Panton-Valentine leukocidin

Cited by 29 publications

References 27 publications

Analysis of the Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrum of Staphylococcus aureus Identifies Mutations That Allow Differentiation of the Main Clonal Lineages

Analysis of the Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrum of Staphylococcus aureus Identifies Mutations That Allow Differentiation of the Main Clonal Lineages

Microbial Typing by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: Do We Need Guidance for Data Interpretation?

Mass spectrometry: a revolution in clinical microbiology?

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