matrix-assisted laser desorption/ionization time of flight
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Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry is used for the determination of molecular weights of different chemical compounds. We describe here the use of MALDI-TOF mass spectrometry to detect a carbapenem antibiotic, meropenem, and its degradation products. Buffered meropenem solution (0.1 mM Tris-HCl, pH 6.8) was mixed with an overnight culture of bacteria. After 3-h incubation, the reaction mixture was centrifuged, and the supernatant was analyzed by MALDI-TOF mass spectrometry. The presence or absence of peaks representing meropenem and its sodium salts was crucial. The average turnaround time of this test, considering the use of overnight culture, is 4 h. We validated this method for the detection of resistance to carbapenems in Enterobacteriaceae and Pseudomonas aeruginosa mediated by carbapenemase production. A total of 124 strains, including 30 carbapenemase-producing strains, were used in the study. The sensitivity of this method is 96.67%, with a specificity of 97.87%. Our results demonstrate the ability of this method to routinely detect carbapenemases in Enterobacteriaceae and Pseudomonas spp. in laboratories. This assay is comparable with a labor-intensive imipenem-hydrolyzing spectrophotometric assay that is a reference method for the detection of carbapenemase. As demonstrated here, MALDI-TOF mass spectrometry may be used in microbiological laboratories not only for microbial identification but also for other applications, such as studies of mechanisms of antibiotic resistance.
- MeSH
- antibakteriální látky analýza MeSH
- bakteriální proteiny metabolismus MeSH
- beta-laktamasy metabolismus MeSH
- Enterobacteriaceae enzymologie MeSH
- lidé MeSH
- Pseudomonas aeruginosa enzymologie MeSH
- senzitivita a specificita MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice metody MeSH
- thienamyciny analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
Cíl práce: MALDI-TOF hmotnostní spektrometrie je v posledních letech široce zaváděna do diagnostických mikrobiologických laboratoří. Poskytuje levnou a rychlou metodu pro taxonomickou identifikaci bakterií a mikromycet. Kromě těchto aplikací je používána i pro detekci mechanismů antibiotické rezistence. V budoucnu lze očekávat další rozšíření i pro jiné aplikace v mikrobiologii. Cílem této studie bylo validovat MALDI-TOF hmotnostní spektrometrii pro identifikaci mykobakterií. Materiál a metody: Do studie bylo zařazeno 30 izolátů Mycobacterium spp. izolovaných v laboratoři mykobakteriologie Fakultní nemocnice v Plzni. Druhová identifikace izolátů byla provedena biochemickými testy, genovými sondami a sekvenací genu pro 16S rRNA. Identifikace MALDI-TOF hmotnostní spektrometrií probíhala s využitím extrakce pomocí silikonových kuliček. Identifikace kmene sekvenací genu pro 16S rRNA byla považována za referenční metodu. Výsledky: Pomocí MALDI-TOF hmotnostní spektrometrie byly správně identifikovány všechny izoláty Mycobacterium spp. (hodnota skóre 1,461–2,168). Jednalo se o druhy Mycobacterium tuberculosis (n = 5), Mycobacterium kansasii (n = 5), Mycobacterium avium (n = 6), Mycobacterium intracelullare (n = 3), Mycobacterium xenopi (n = 3), Mycobacterium gordonae (n=1), Mycobacterium abscessus (n=1), Mycobacterium kumamotonense (n=2), Mycobacterium mantenii (n = 1), Mycobacterium lentiflavum (n = 1), Mycobacterium fortuitum (n = 1), Mycobacterium scrofulaceum (n = 1). Závěr: Identifikace hmotnostní spektrometrií je tedy vhodná k rutinní identifikaci Mycobacterium spp. v laboratořích, kde již je tato metoda zavedena pro konvenční identifikaci mikrobů.
Study objective: Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has recently been widely used in diagnostic microbiological laboratories. It is a cheap and rapid method for the identification of bacteria and micromycetes. Apart from this purpose, it is also used for the detection of antibiotic resistance mechanisms. It has the potential to be extended for other purposes in microbiology. The aim of this study was to validate MALDI-TOF MS for the identification of mycobacteria. Material and methods: Thirty isolates of Mycobacterium spp. isolated in the Laboratory of Mycobacteriology of the Plzeň University Hospital were included in the study. The isolates were identified to the species level using biochemical tests, gene probes, and sequencing of the gene encoding 16S rRNA. The identification by MALDI-TOF MS was performed with the use of silica beads. Strain identification by sequencing the gene encoding 16S rRNA was considered as the reference method. Results: MALDI-TOF MS correctly identified all isolates of Mycobacterium spp. (score range 1.461 – 2.168). The species identified were Mycobacterium tuberculosis (n= 5), Mycobacterium kansasii (n=5), Mycobacterium avium (n=6), Mycobacterium intracelullare (n=3), Mycobacterium xenopi (n=3), Mycobacterium gordonae (n=1), Mycobacterium abscessus (n=1), Mycobacterium kumamotonense (n=2), Mycobacterium mantenii (n=1), Mycobacterium lentiflavum (n=1), Mycobacterium fortuitum (n=1), and Mycobacterium scrofulaceum (n=1). Conclusion: MALDI-TOF MS is a suitable tool for the routine identification of Mycobacterium spp. in laboratories using this method for the conventional identification of microbes.
- MeSH
- laboratoře MeSH
- lidé MeSH
- Mycobacterium * genetika izolace a purifikace klasifikace MeSH
- mykobakteriózy * diagnóza MeSH
- RNA ribozomální 16S MeSH
- sekvenční analýza DNA MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice * využití MeSH
- techniky typizace bakterií metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
BACKGROUND: Phlebotomine sand flies are incriminated in the transmission of several human and veterinary pathogens. To elucidate their role as vectors, proper species identification is crucial. Since traditional morphological determination is based on minute and often dubious characteristics on their head and genitalia, which require certain expertise and may be damaged in the field-collected material, there is a demand for rapid, simple and cost-effective molecular approaches. METHODS: Six laboratory-reared colonies of phlebotomine sand flies belonging to five species and four subgenera (Phlebotomus, Paraphlebotomus, Larroussius, Adlerius) were used to evaluate the discriminatory power of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Various storage conditions and treatments, including the homogenization in either distilled water or given concentrations of formic acid, were tested on samples of both sexes. RESULTS: Specimens of all five analysed sand fly species produced informative, reproducible and species-specific protein spectra that enabled their conclusive species identification. The method also distinguished between two P. sergenti colonies originating from different geographical localities. Protein profiles within a species were similar for specimens of both sexes. Tested conditions of specimen storage and sample preparation give ground to a standard protocol that is generally applicable on analyzed sand fly specimens. CONCLUSIONS: Species identification of sand flies by MALDI-TOF MS is feasible and represents a novel promising tool to improve biological and epidemiological studies on these medically important insects.
- MeSH
- hmyzí proteiny metabolismus MeSH
- proteomika MeSH
- Psychodidae klasifikace metabolismus MeSH
- shluková analýza MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice * MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In our laboratory, we have been studying the reductive processes that occur during matrix-assisted laser desorption/ionization (MALDI) experiments. Recently, we have finished an analysis of the DHB matrix effect on the azo group in cyclic peptides. However, deep understanding of disulfide bond behaviour during a mass spectrometry (MS) experiment is much more important in proteomics as its reduction can cause serious errors in protein spectra interpretation. Therefore, we have focused on intra- and intermolecular disulfide bonds as well as disulfide bonds connecting cysteine and 2-thio-5-nitrobenzoic acid (TNB, Ellman's reagent modification) in model peptides during MALDI MS measurements. While the reduction was not observed for intra- and intermolecular cysteine-cysteine disulfide bonds, the disulfide connection between cysteine and TNB was always affected. It was proved that TNB and Ellman's reagent can act as a matrix itself. The results obtained enabled us to propose a reaction mechanism model which is able to describe the phenomena observed during the desorption/ionization process of disulfide-containing molecules.
- MeSH
- cystein chemie MeSH
- disulfidy chemie MeSH
- ionty chemie MeSH
- kyselina dithionitrobenzoová chemie MeSH
- molekulární sekvence - údaje MeSH
- nitrobenzoany chemie MeSH
- peptidy chemie MeSH
- sekvence aminokyselin MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice metody MeSH
- sulfhydrylové sloučeniny chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This study describes a new method for simultaneous identification of uropathogens in the case of polybacterial urinary tract infections. The method utilizes recently developed preparative isoelectric focusing (IEF) in cellulose-based separation medium with a subsequent analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Preparative IEF was successfully used for both purification and separation of bacteria, Escherichia coli (pI 4.6) and Staphylococcus aureus (pI 3.4), in urine samples. The focused zones of bacteria, localized by the positions of focused colored pI markers, were easily collected from the separation media after the IEF analysis and then unambiguously identified by MALDI-TOF MS. The proposed method enables the identification of bacteria in urine specimens when the concentration of individual bacteria is ≥104 cells mL-1. Another benefit is the viability of bacteria extracted from the collected fractions after preparative IEF.
- MeSH
- Escherichia coli izolace a purifikace MeSH
- infekce močového ústrojí mikrobiologie moč MeSH
- isoelektrická fokusace metody MeSH
- lidé MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice metody MeSH
- Staphylococcus aureus izolace a purifikace MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
RATIONALE: Distinguishing between individual bacterial strains below the species level is a challenge to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial profiling. We propose a quick method for improving strain differentiation of two Staphylococcus and one Bacillus species. METHODS: An alternative procedure to the extraction protocol recommended by Bruker Daltonics was developed. Ethanol-sterilized cells of six S. aureus and six S. haemolyticus strains were digested by trypsin using 2-min microwave irradiation and were then analyzed. Twenty-eight strains belonging to two ecotypes of B. subtilis were subjected to the same procedure to extend the scope of the method. RESULTS: S. aureus and S. haemolyticus strains, only partially distinguishable by the standard sample preparation procedure, were subjected to microwave-assisted tryptic digestion. The repeatability of the procedure was checked in three experiments accomplished at weekly intervals. Clear distinction of the strains was achieved by cluster analysis. The differentiation of B. subtilis ecotypes was also improved significantly by the digestion method. The discriminatory power of the novel method was supported by an increase in the number of strain-specific peaks, as compared to the standard method. CONCLUSIONS: The method modulates the discriminatory power of MALDI-TOF MS profiling. The differentiation of a set of S. aureus, S. haemolyticus and B. subtilis strains was improved significantly after microwave-accelerated tryptic digestion of the cellular material.
- MeSH
- Bacillus chemie klasifikace MeSH
- mikrovlny MeSH
- molekulární typizace metody MeSH
- shluková analýza MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice metody MeSH
- Staphylococcus chemie klasifikace MeSH
- trypsin MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been recently introduced to many diagnostic microbiological laboratories. Besides the identification of bacteria and fungi, that technique provides a potentially useful tool for the detection of antimicrobial resistance, especially of that conferred by β-lactamases. Here, we describe an assay allowing a detection of meropenem hydrolysis in clinical isolates of Enterobacteriaceae, Pseudomonas spp., and Acinetobacter baumannii using MALDI-TOF MS. This method is able to confirm carbapenemases within 3 h. The results are important for proper and fast intervention to limit the spread of carbapenemase-producing bacteria and provide information for appropriate initial therapy of the infections caused by these microbes.
- MeSH
- Acinetobacter baumannii účinky léků enzymologie genetika izolace a purifikace MeSH
- antibakteriální látky farmakologie MeSH
- bakteriální proteiny genetika metabolismus MeSH
- beta-laktamasy genetika metabolismus MeSH
- beta-laktamová rezistence genetika MeSH
- biotest * MeSH
- exprese genu MeSH
- hydrolýza MeSH
- infekce bakteriemi rodu Acinetobacter diagnóza farmakoterapie mikrobiologie MeSH
- lidé MeSH
- pseudomonádové infekce diagnóza farmakoterapie mikrobiologie MeSH
- Pseudomonas účinky léků enzymologie genetika izolace a purifikace MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
- thienamyciny farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
RATIONALE: The bacterial genus Cronobacter was established quite recently, in 2008. Therefore, its systematic classification is still in progress as well as the risk assessment of Cronobacter strains. The possibility of rapid identification within the biogroup level has an essential epidemiological significance. We examined the potential of mass spectrometry to accomplish this task on species Cronobacter sakazakii comprising eight different biogroups. METHODS: Members of all Cronobacter sakazakii biogroups were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) using intact cells. Analyses were performed on a Biflex IV MALDI-TOF mass spectrometer in the range of 2000 to 20 000 Da in linear mode with an accelerated voltage of 19 kV. RESULTS: Optimal conditions for a proper identification of biogroups, such as suitable cultivation media or growth time of bacteria, were investigated. The biomarker patterns characterizing each of the Cronobacter sakazakii biogroups were obtained. The established identification protocol was applied to ten previously non-identified strains and their biogroups were successfully determined. CONCLUSIONS: The presented work is the first report of successful and rapid bacterial biogroup taxonomy classification using MALDI-TOF-MS that could substitute demanding biochemical testing.
- MeSH
- biologické markery analýza chemie MeSH
- Cronobacter sakazakii chemie klasifikace růst a vývoj MeSH
- kultivační média chemie metabolismus MeSH
- reprodukovatelnost výsledků MeSH
- shluková analýza MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice metody MeSH
- techniky typizace bakterií metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
