scholarly journals Multi-laboratory validation study of multilocus variable-number tandem repeat analysis (MLVA) for Salmonella enterica serovar Enteritidis, 2015

2017 ◽  
Vol 22 (9) ◽  
Author(s):  
Tansy Peters ◽  
Sophie Bertrand ◽  
Jonas T Björkman ◽  
Lin T Brandal ◽  
Derek J Brown ◽  
...  
Keyword(s):  
North America ◽  
Tandem Repeat ◽  
Validation Study ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
European Economic Area ◽  
The European Union ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Typing Method ◽  
Repeat Analysis

Multilocus variable-number tandem repeat analysis (MLVA) is a rapid and reproducible typing method that is an important tool for investigation, as well as detection, of national and multinational outbreaks of a range of food-borne pathogens. Salmonella enterica serovar Enteritidis is the most common Salmonella serovar associated with human salmonellosis in the European Union/European Economic Area and North America. Fourteen laboratories from 13 countries in Europe and North America participated in a validation study for MLVA of S. Enteritidis targeting five loci. Following normalisation of fragment sizes using a set of reference strains, a blinded set of 24 strains with known allele sizes was analysed by each participant. The S. Enteritidis 5-loci MLVA protocol was shown to produce internationally comparable results as more than 90% of the participants reported less than 5% discrepant MLVA profiles. All 14 participating laboratories performed well, even those where experience with this typing method was limited. The raw fragment length data were consistent throughout, and the inter-laboratory validation helped to standardise the conversion of raw data to repeat numbers with at least two countries updating their internal procedures. However, differences in assigned MLVA profiles remain between well-established protocols and should be taken into account when exchanging data.

scholarly journals Genotyping North American Animal Mycobacterium Bovis Isolates Using Multilocus Variable Number Tandem Repeat Analysis

2008 ◽  
Vol 20 (6) ◽  
pp. 707-715 ◽  
Author(s):  
Lorene R. Martinez ◽  
Beth Harris ◽  
William C. Black ◽  
Robert M. Meyer ◽  
Patrick J. Brennan ◽  
...  
Keyword(s):  
North America ◽  
Mycobacterium Bovis ◽  
Tandem Repeat ◽  
North American ◽  
Variable Number Tandem Repeat ◽  
Epidemiological Data ◽  
Variable Number ◽  
Repeat Analysis ◽  
Trace Back ◽  
Animal Isolates

Multilocus variable number tandem repeat analysis (MLVA) has recently emerged as a genotyping method that is both robust and highly discriminatory for the differentiation of Mycobacterium tuberculosis complex (MTBC) strains, including Mycobacterium bovis. However, MLVA assessment of M. bovis isolates recovered from animals in North America has been limited. Using an epidemiologically diverse set of 41 North American M. bovis animal isolates, MLVA, based on 27 published variable number tandem repeat (VNTR) loci, was evaluated. Nineteen loci displayed polymorphism, which resulted in differentiation of 21 unique MLVA genotypes. A subset of 6 loci differentiated the isolates into 14 genetically related groups that displayed remarkable concordance with the epidemiological data gathered via traditional trace-back methods. In most cases, MLVA exhibited greater resolution than spoligotyping, which differentiated the isolates into 11 groups. MLVA genotyping of M. bovis shows great potential as a molecular typing tool for characterizing the epidemiology of M. bovis animal infections in North America. However, the greatest resolution was achieved by using a combination of both MLVA and spoligotyping.

scholarly journals Subtyping of a Large Collection of Historical Listeria monocytogenes Strains from Ontario, Canada, by an Improved Multilocus Variable-Number Tandem-Repeat Analysis (MLVA)

2013 ◽  
Vol 79 (20) ◽  
pp. 6472-6480 ◽  
Author(s):  
S. Saleh-Lakha ◽  
V. G. Allen ◽  
J. Li ◽  
F. Pagotto ◽  
J. Odumeru ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Tandem Repeat ◽  
Food Chain ◽  
Diversity Index ◽  
Variable Number Tandem Repeat ◽  
Diversity Indices ◽  
Variable Number ◽  
Typing Method ◽  
Content Type ◽  
Repeat Analysis

ABSTRACTListeria monocytogenesis responsible for severe and often fatal food-borne infections in humans. A collection of 2,421L. monocytogenesisolates originating from Ontario's food chain between 1993 and 2010, along with Ontario clinical isolates collected from 2004 to 2010, was characterized using an improved multilocus variable-number tandem-repeat analysis (MLVA). The MLVA method was established based on eight primer pairs targeting seven variable-number tandem-repeat (VNTR) loci in two 4-plex fluorescent PCRs. Diversity indices and amplification rates of the individual VNTR loci ranged from 0.38 to 0.92 and from 0.64 to 0.99, respectively. MLVA types and pulsed-field gel electrophoresis (PFGE) patterns were compared using Comparative Partitions analysis involving 336 clinical and 99 food and environmental isolates. The analysis yielded Simpson's diversity index values of 0.998 and 0.992 for MLVA and PFGE, respectively, and adjusted Wallace coefficients of 0.318 when MLVA was used as a primary subtyping method and 0.088 when PFGE was a primary typing method. Statistical data analysis using BioNumerics allowed for identification of at least 8 predominant and persistentL. monocytogenesMLVA types in Ontario's food chain. The MLVA method correctly clustered epidemiologically related outbreak strains and separated unrelated strains in a subset analysis. An MLVA database was established for the 2,421L. monocytogenesisolates, which allows for comparison of data among historical and new isolates of different sources. The subtyping method coupled with the MLVA database will help in effective monitoring/prevention approaches to identify environmental contamination by pathogenic strains ofL. monocytogenesand investigation of outbreaks.

scholarly journals Multiple-Locus Variable-Number Tandem Repeat Analysis of Dutch Bordetella pertussis Strains Reveals Rapid Genetic Changes with Clonal Expansion during the Late 1990s

2004 ◽  
Vol 186 (16) ◽  
pp. 5496-5505 ◽  
Author(s):  
Leo M. Schouls ◽  
Han G. J. van der Heide ◽  
Luc Vauterin ◽  
Paul Vauterin ◽  
Frits R. Mooi
Keyword(s):  
The Netherlands ◽  
Tandem Repeat ◽  
Bordetella Pertussis ◽  
Minimum Spanning Tree ◽  
Whooping Cough ◽  
Variable Number Tandem Repeat ◽  
Clonal Expansion ◽  
Variable Number ◽  
Multiple Locus ◽  
Repeat Analysis

ABSTRACT Bordetella pertussis, the causative agent of whooping cough, has remained endemic in The Netherlands despite extensive nationwide vaccination since 1953. In the 1990s, several epidemic periods have resulted in many cases of pertussis. We have proposed that strain variation has played a major role in the upsurges of this disease in The Netherlands. Therefore, molecular characterization of strains is important in identifying the causes of pertussis epidemiology. For this reason, we have developed a multiple-locus variable-number tandem repeat analysis (MLVA) typing system for B. pertussis. By combining the MLVA profile with the allelic profile based on multiple-antigen sequence typing, we were able to further differentiate strains. The relationships between the various genotypes were visualized by constructing a minimum spanning tree. MLVA of Dutch strains of B. pertussis revealed that the genotypes of the strains isolated in the prevaccination period were diverse and clearly distinct from the strains isolated in the 1990s. Furthermore, there was a decrease in diversity in the strains from the late 1990s, with a remarkable clonal expansion that coincided with the epidemic periods. Using this genotyping, we have been able to show that B. pertussis is much more dynamic than expected.

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