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Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification and clustering of Neisseria gonorrhoeae.

Carannante A, De Carolis E, Vacca P, Vella A, Vocale C, De Francesco MA, Cusini M, Del Re S, Dal Conte I, Cristaudo A, Ober P, Sanguinetti M, Stefanelli P - BMC Microbiol. (2015)

Bottom Line: Molecular typing by NG-MAST showed 28 sequence types (STs); G1407 was the predominant accounting for 75 gonococci.All the 93 gonococci, except one, were correctly identified at species level by MALDI-TOF MS and G1407 isolates were divided into two clusters.Moreover, additional studies are required to collect more data on the performance of MALDI-TOF MS for gonococci.

View Article: PubMed Central - PubMed

Affiliation: Departmentof Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy. anna.carannante@iss.it.

ABSTRACT

Background: The sexually transmitted infection gonorrhea remains a public health concern for becoming resistant to drug treatments available. The purpose of this study was to evaluate the usefulness of the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify and cluster Neisseria gonorrhoeae. From a current monitoring in Italy, as part of the European Gonococcal Antimicrobial Surveillance Programme (EURO-GASP), 93 gonococci collected from 2007 to 2012 susceptible (44 isolates) and resistant (49 isolates) to cefixime were selected. Minimum Inhibitory Concentration (MIC) values for cefixime was assessed by Etest carried out in agreement with the manufacturer's instructions and interpreted referring to European Committee on Antimicrobial Susceptibility testing (EUCAST) clinical breakpoints criteria. Data obtained by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and the dendrogram based on the concatenation of porB and tbpB genes were evaluated. MALDI-TOF MS, to reconfirm gonorrhea identification, analyzed single colonies from freshly grown isolates and applied directly on a ground-steel MALDI target plate. For the MALDI-TOF dendrogram cluster analysis, MSPs (Main Spectrum Profile) from each isolate were created acquiring 5000 shots from 10 technical replicates obtained from bacteria extraction.

Results: Molecular typing by NG-MAST showed 28 sequence types (STs); G1407 was the predominant accounting for 75 gonococci. All the 93 gonococci, except one, were correctly identified at species level by MALDI-TOF MS and G1407 isolates were divided into two clusters.

Conclusion: MALDI-TOF MS for a real-time detection and cluster analysis of gonorrhea is a promising tool for surveillance purposes. Moreover, additional studies are required to collect more data on the performance of MALDI-TOF MS for gonococci.

No MeSH data available.


Related in: MedlinePlus

Cluster analysis of MALDI-TOF MS spectra obtained for 93 N. gonorrhoeae isolates. In the MSP dendrogram, relative distance between isolates is displayed as arbitrary units. Zero indicates complete similarity and 1000 indicates complete dissimilarity. The arbitrary distance level of 600 was chosen for isolates clustering evaluation. The STs listed in the Figure are different from the genogroup (G) 1407
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Fig3: Cluster analysis of MALDI-TOF MS spectra obtained for 93 N. gonorrhoeae isolates. In the MSP dendrogram, relative distance between isolates is displayed as arbitrary units. Zero indicates complete similarity and 1000 indicates complete dissimilarity. The arbitrary distance level of 600 was chosen for isolates clustering evaluation. The STs listed in the Figure are different from the genogroup (G) 1407

Mentions: As shown in Fig. 3, in relation to their mass signals and intensities, a hierarchic dendrogram clustered the 93 gonococci in two main groups: a large group (n = 77 isolates) it has been divided into two sub-clusters, the remaining 15 isolates were grouped into a smaller one. Conversely, 1 single isolate was grouped in a different cluster, according to the arbitrary distance level of 600 (Fig. 3). Dendrograms obtained from MALDI-TOF MS hierarchical cluster analysis and concatenation of tbpB and porB sequences were compared; the G1407 clustered as a single clone by NG-MAST, whilst turn to be divided in two groups by dendrogram obtained with MALDI-TOF MS analysis. In particular, in one cluster have been included isolates belonging to G1407 except for one that had the ST4232 with the tbpB allele 110 present among the G1407 isolates. In the second cluster, 60 out of 77 isolates belonged to G1407. The remaining 17 isolates defined small groups of 2 isolates, i. e. ST225 and ST5107 or ST4517 and ST4518 (Fig. 3).Fig. 3


Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification and clustering of Neisseria gonorrhoeae.

Carannante A, De Carolis E, Vacca P, Vella A, Vocale C, De Francesco MA, Cusini M, Del Re S, Dal Conte I, Cristaudo A, Ober P, Sanguinetti M, Stefanelli P - BMC Microbiol. (2015)

Cluster analysis of MALDI-TOF MS spectra obtained for 93 N. gonorrhoeae isolates. In the MSP dendrogram, relative distance between isolates is displayed as arbitrary units. Zero indicates complete similarity and 1000 indicates complete dissimilarity. The arbitrary distance level of 600 was chosen for isolates clustering evaluation. The STs listed in the Figure are different from the genogroup (G) 1407
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4514454&req=5

Fig3: Cluster analysis of MALDI-TOF MS spectra obtained for 93 N. gonorrhoeae isolates. In the MSP dendrogram, relative distance between isolates is displayed as arbitrary units. Zero indicates complete similarity and 1000 indicates complete dissimilarity. The arbitrary distance level of 600 was chosen for isolates clustering evaluation. The STs listed in the Figure are different from the genogroup (G) 1407
Mentions: As shown in Fig. 3, in relation to their mass signals and intensities, a hierarchic dendrogram clustered the 93 gonococci in two main groups: a large group (n = 77 isolates) it has been divided into two sub-clusters, the remaining 15 isolates were grouped into a smaller one. Conversely, 1 single isolate was grouped in a different cluster, according to the arbitrary distance level of 600 (Fig. 3). Dendrograms obtained from MALDI-TOF MS hierarchical cluster analysis and concatenation of tbpB and porB sequences were compared; the G1407 clustered as a single clone by NG-MAST, whilst turn to be divided in two groups by dendrogram obtained with MALDI-TOF MS analysis. In particular, in one cluster have been included isolates belonging to G1407 except for one that had the ST4232 with the tbpB allele 110 present among the G1407 isolates. In the second cluster, 60 out of 77 isolates belonged to G1407. The remaining 17 isolates defined small groups of 2 isolates, i. e. ST225 and ST5107 or ST4517 and ST4518 (Fig. 3).Fig. 3

Bottom Line: Molecular typing by NG-MAST showed 28 sequence types (STs); G1407 was the predominant accounting for 75 gonococci.All the 93 gonococci, except one, were correctly identified at species level by MALDI-TOF MS and G1407 isolates were divided into two clusters.Moreover, additional studies are required to collect more data on the performance of MALDI-TOF MS for gonococci.

View Article: PubMed Central - PubMed

Affiliation: Departmentof Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy. anna.carannante@iss.it.

ABSTRACT

Background: The sexually transmitted infection gonorrhea remains a public health concern for becoming resistant to drug treatments available. The purpose of this study was to evaluate the usefulness of the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify and cluster Neisseria gonorrhoeae. From a current monitoring in Italy, as part of the European Gonococcal Antimicrobial Surveillance Programme (EURO-GASP), 93 gonococci collected from 2007 to 2012 susceptible (44 isolates) and resistant (49 isolates) to cefixime were selected. Minimum Inhibitory Concentration (MIC) values for cefixime was assessed by Etest carried out in agreement with the manufacturer's instructions and interpreted referring to European Committee on Antimicrobial Susceptibility testing (EUCAST) clinical breakpoints criteria. Data obtained by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and the dendrogram based on the concatenation of porB and tbpB genes were evaluated. MALDI-TOF MS, to reconfirm gonorrhea identification, analyzed single colonies from freshly grown isolates and applied directly on a ground-steel MALDI target plate. For the MALDI-TOF dendrogram cluster analysis, MSPs (Main Spectrum Profile) from each isolate were created acquiring 5000 shots from 10 technical replicates obtained from bacteria extraction.

Results: Molecular typing by NG-MAST showed 28 sequence types (STs); G1407 was the predominant accounting for 75 gonococci. All the 93 gonococci, except one, were correctly identified at species level by MALDI-TOF MS and G1407 isolates were divided into two clusters.

Conclusion: MALDI-TOF MS for a real-time detection and cluster analysis of gonorrhea is a promising tool for surveillance purposes. Moreover, additional studies are required to collect more data on the performance of MALDI-TOF MS for gonococci.

No MeSH data available.


Related in: MedlinePlus