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Comparison of methods based on different molecular epidemiological markers for typing of Mycobacterium tuberculosis complex strains: interlaboratory study of discriminatory power and reproducibility.

ABSTRACT: In this study, the currently known typing methods for Mycobacterium tuberculosis isolates were evaluated with regard to reproducibility, discrimination, and specificity. Therefore, 90 M. tuberculosis complex strains, originating from 38 countries, were tested in five restriction fragment length polymorphism (RFLP) typing methods and in seven PCR-based assays. In all methods, one or more repetitive DNA elements were targeted. The strain typing and the DNA fingerprint analysis were performed in the laboratory most experienced in the respective method. To examine intralaboratory reproducibility, blinded duplicate samples were included. The specificities of the various methods were tested by inclusion of 10 non-M. tuberculosis complex strains. All five RFLP typing methods were highly reproducible. The reliability of the PCR-based methods was highest for the mixed-linker PCR, followed by variable numbers of tandem repeat (VNTR) typing and spoligotyping. In contrast, the double repetitive element PCR (DRE-PCR), IS6110 inverse PCR, IS6110 ampliprinting, and arbitrarily primed PCR (APPCR) typing were found to be poorly reproducible. The 90 strains were best discriminated by IS6110 RFLP typing, yielding 84 different banding patterns, followed by mixed-linker PCR (81 patterns), APPCR (71 patterns), RFLP using the polymorphic GC-rich sequence as a probe (70 patterns), DRE-PCR (63 patterns), spoligotyping (61 patterns), and VNTR typing (56 patterns). We conclude that for epidemiological investigations, strain differentiation by IS6110 RFLP or mixed-linker PCR are the methods of choice. A strong association was found between the results of different genetic markers, indicating a clonal population structure of M. tuberculosis strains. Several separate genotype families within the M. tuberculosis complex could be recognized on the basis of the genetic markers used.

SUBMITTER: Kremer K

PROVIDER: S-EPMC85295 | biostudies-literature | 1999 Aug

REPOSITORIES: biostudies-literature

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Comparison of methods based on different molecular epidemiological markers for typing of Mycobacterium tuberculosis complex strains: interlaboratory study of discriminatory power and reproducibility.

Kremer K K van Soolingen D D Frothingham R R Haas W H WH Hermans P W PW Martín C C Palittapongarnpim P P Plikaytis B B BB Riley L W LW Yakrus M A MA Musser J M JM van Embden J D JD

Journal of clinical microbiology 19990801 8

In this study, the currently known typing methods for Mycobacterium tuberculosis isolates were evaluated with regard to reproducibility, discrimination, and specificity. Therefore, 90 M. tuberculosis complex strains, originating from 38 countries, were tested in five restriction fragment length polymorphism (RFLP) typing methods and in seven PCR-based assays. In all methods, one or more repetitive DNA elements were targeted. The strain typing and the DNA fingerprint analysis were performed in th ...[more]

PMID: 10405410

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Project description:BackgroundSeveral technical hurdles and limitations have restricted the use of IS6110 restriction fragment length polymorphism (IS6110 RFLP), the most effective typing method for detecting recent tuberculosis (TB) transmission events. This has prompted us to conceive an alternative modality, IS6110-5'3'FP, a plasmid-based cloning approach coupled to a single PCR amplification of differentially labeled 5' and 3' IS6110 polymorphic ends and their automated fractionation on a capillary sequencer. The potential of IS6110-5'3'FP to be used as an alternative to IS6110 RFLP has been previously demonstrated, yet further technical improvements are still required for optimal discriminatory power and versatility.ObjectivesHere we introduced critical amendments to the original IS6110-5'3'FP protocol and compared its performance to that of 24-loci multiple interspersed repetitive unit-variable number tandem repeats (MIRU-VNTR), the current standard method for TB transmission analyses.MethodsIS6110-5'3'FP protocol modifications involved: (i) the generation of smaller-sized polymorphic fragments for efficient cloning and PCR amplification, (ii) omission of the plasmid amplification step in E. coli for shorter turnaround times, (iii) the use of more stable fluorophores for increased sensitivity, (iv) automated subtraction of background fluorescent signals, and (v) the automated conversion of fluorescent peaks into binary data.ResultsIn doing so, the overall turnaround time of IS6110-5'3'FP was reduced to 4 hours. The new protocol allowed detecting almost all 5' and 3' IS6110 polymorphic fragments of any given strain, including IS6110 high-copy number Beijing strains. IS6110-5'3'FP proved much more discriminative than 24-loci MIRU-VNTR, particularly with strains of the M. tuberculosis lineage 4.ConclusionsThe IS6110-5'3'FP protocol described herein reached the optimal discriminatory potential of IS6110 fingerprinting and proved more accurate than 24-loci MIRU-VNTR in estimating recent TB transmission. The method, which is highly cost-effective, was rendered versatile enough to prompt its evaluation as an automatized solution for a TB integrated molecular surveillance.

Project description:Historically, a number of typing methods have been evaluated for Staphylococcus aureus strain characterization. The emergence of contemporary strains of community-associated S. aureus, and the ensuing epidemic with a predominant strain type (USA300), necessitates re-evaluation of the discriminatory power of these typing methods for discerning molecular epidemiology and transmission dynamics, essential to investigations of hospital and community outbreaks. We compared the discriminatory index of 5 typing methods for contemporary S. aureus strain characterization. Children presenting to St. Louis Children's Hospital and community pediatric practices in St. Louis, Missouri (MO), with community-associated S. aureus infections were enrolled. Repetitive sequence-based PCR (repPCR), pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), staphylococcal protein A (spa), and staphylococcal cassette chromosome (SCC) mec typing were performed on 200 S. aureus isolates. The discriminatory index of each method was calculated using the standard formula for this metric, where a value of 1 is highly discriminatory and a value of 0 is not discriminatory. Overall, we identified 26 distinct strain types by repPCR, 17 strain types by PFGE, 30 strain types by MLST, 68 strain types by spa typing, and 5 strain types by SCCmec typing. RepPCR had the highest discriminatory index (D) of all methods (D?=?0.88), followed by spa typing (D?=?0.87), MLST (D?=?0.84), PFGE (D?=?0.76), and SCCmec typing (D?=?0.60). The method with the highest D among MRSA isolates was repPCR (D?=?0.64) followed by spa typing (D?=?0.45) and MLST (D?=?0.44). The method with the highest D among MSSA isolates was spa typing (D?=?0.98), followed by MLST (D?=?0.93), repPCR (D?=?0.92), and PFGE (D?=?0.89). Among isolates designated USA300 by PFGE, repPCR was most discriminatory, with 10 distinct strain types identified (D?=?0.63). We identified 45 MRSA isolates which were classified as identical by PFGE, MLST, spa typing, and SCCmec typing (USA300, ST8, t008, SCCmec IV, respectively); within this collection, there were 5 distinct strain types identified by repPCR. The typing methods yielded comparable discriminatory power for S. aureus characterization overall; when discriminating among USA300 isolates, repPCR retained the highest discriminatory power. This property is advantageous for investigations conducted in the era of contemporary S. aureus infections.

Project description:BACKGROUND: Genotyping methods developed to survey the transmission dynamics of Mycobacterium tuberculosis currently rely on the interpretation of restriction and amplification profiles. Multispacer sequence typing (MST) genotyping is based on the sequencing of several intergenic regions selected after complete genome sequence analysis. It has been applied to various pathogens, but not to M. tuberculosis. METHODS AND FINDINGS: In M. tuberculosis, the MST approach yielded eight variable intergenic spacers which included four previously described variable number tandem repeat loci, one single nucleotide polymorphism locus and three newly evaluated spacers. Spacer sequence stability was evaluated by serial subculture. The eight spacers were sequenced in a collection of 101 M. tuberculosis strains from five phylogeographical lineages, and yielded 29 genetic events including 13 tandem repeat number variations (44.82%), 11 single nucleotide mutations (37.93%) and 5 deletions (17.24%). These 29 genetic events yielded 32 spacer alleles or spacer-types (ST) with an index of discrimination of 0.95. The distribution of M. tuberculosis isolates into ST profiles correlated with their assignment into phylogeographical lineages. Blind comparison of a further 93 M. tuberculosis strains by MST and restriction fragment length polymorphism-IS6110 fingerprinting and mycobacterial interspersed repetitive units typing, yielded an index of discrimination of 0.961 and 0.992, respectively. MST yielded 41 different profiles delineating 16 related groups and proved to be more discriminatory than IS6110-based typing for isolates containing < 8 IS6110 copies (P<0.0003). MST was successfully applied to 7/10 clinical specimens exhibiting a Cts < or = 42 cycles in internal transcribed spacer-real time PCR. CONCLUSIONS: These results support MST as an alternative, sequencing-based method for genotyping low IS6110 copy-number M. tuberculosis strains. The M. tuberculosis MST database is freely available (http://ifr48.timone.univ-mrs.fr/MST_MTuberculosis/mst).

Dataset Information

Comparison of methods based on different molecular epidemiological markers for typing of Mycobacterium tuberculosis complex strains: interlaboratory study of discriminatory power and reproducibility.

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Comparison of methods based on different molecular epidemiological markers for typing of Mycobacterium tuberculosis complex strains: interlaboratory study of discriminatory power and reproducibility.

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