Variable number tandem repeat loci providing discrimination within widespread genotypes of Acinetobacter baumannii

Abstract

Some genotypes of Acinetobacter baumannii, defined by pulsed-field gel electrophoresis (PFGE), have been found in many hospitals. Our aim was to find variable number tandem repeat (VNTR) loci capable of providing discrimination among isolates with highly similar or identical PFGE profiles, to gain insights into the epidemiology. Thirteen loci identified in A. baumannii ATCC 17978 were tested using a panel of isolates that included multiple representatives of genotypes belonging to the three European clonal lineages. Two loci, with repeat units of 9 and 6 bp respectively were selected. Repeat numbers varied between 3 and 29, and 9 and 26 respectively at the two loci. The repeat numbers of representatives of each genotype often differed between hospitals, providing a means of tracking patient transfers and possible transmissions between patients. The results suggest that this analysis accurately reflects the known epidemiological information, and provides a valuable tool for cross-infection studies.

Comparison of Multiple-Locus Variable-Number Tandem-Repeat Analysis with Pulsed-Field Gel Electrophoresis Typing of Acinetobacter baumannii in China

“…In contrast, multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA), based on the copy numbers of tandem-repeat units (TRs) of VNTR loci, is a highly reproducible and portable typing method and can be easily shared. So far, 10 VNTRs that provided sufficient repeat polymorphism for fine typing of clinical isolates have been described in A. baumannii, and three different selections of loci have been evaluated, including a 2-locus assay (9), an MLVA-8 scheme (10), and a partially automated MLVA-10 Orsay scheme (11).…”

Use of the Accessory Genome for Characterization and Typing of Acinetobacter baumannii

“…For example, the predominant PFGE type from United Kingdom hospitals, known as OXA-23 clone 1, a sublineage of international clone II, has been found in over 60 hospitals. We have successfully used variable-number tandem repeat (VNTR) analysis at two highly discriminatory loci to provide fine typing within a PFGE cluster, which does appear to reflect the known epidemiology (29). However, the finding of genetically similar isolates in multiple locations, sometimes with no known epidemiological link, raises questions about the relative roles of spread and selection by antibiotics, and it would be helpful to compare these isolates in more detail.…”

A preliminary molecular epidemiologic study using analysis of variable number of tandem repeats of Acinetobacter baumannii OXA-23 producing strains isolated from hospitals in Rio de Janeiro State, Brazil

“…VNTR have been found in the genomes of several bacteria including Staphylococcus aureus, Bacillus anthracis, Bacillus cereus and Neisseria 7,8,9,10,11 . Turton et al 12 and Pourcel et al 6 suggested the use of VNTR as a complement or even for substitution of the other methodologies. VNTR is a technique based on the PCR detection of specific repetitive sequence(s) active in different individuals, which results in an electrophoretic fingerprint.…”

“…VNTR is a technique based on the PCR detection of specific repetitive sequence(s) active in different individuals, which results in an electrophoretic fingerprint. Multiple-locus VNTR analysis, also known as MLVA, presents the polymorphism among different tandemly repeated DNA sequences 12 . The division of VNTR markers into two groups is made according to their size and rate of evolution.…”

“…It was suggested previously that determination of the number of repeats in VNTR1 and VNTR10 could be valuable in cross-infection studies, with VNTR1 providing the greatest level of discrimination 12 , at least among the isolates of OXA-23 clone 1 that were included in that study. It is clear that the discriminatory power of this technique depends on the choice of locus.…”