Article

High-frequency endonuclease (REA) typing: results from the WHO collaborative study group on subtyping of Listeria monocytogenes.

Department of Clinical Microbiology, Statens Seruminstitut, Copenhagen S, Denmark.
International Journal of Food Microbiology (Impact Factor: 3.43). 11/1996; 32(3):313-24. DOI: 10.1016/S0168-1605(96)01145-2
Source: PubMed

ABSTRACT Eighty isolates of Listeria monocytogenes were typed by high-frequency restriction endonuclease analysis. Two laboratories participated in the study with two restriction enzymes each. The enzymes used were EcoRI, Hae1II, HhaI. and its isoschizomer Cfo1. EcoRI was less discriminatory than the other enzymes. The profiles generated by Hha1 and CfoI were not fully stable for some closely related isolates. The size and the number of restriction bands generated by Hha1 in one laboratory and its isoschizomer Cfo1 in another laboratory were directly comparable. This indicates that REA-typing may be used as a definitive typing method for Listeria monocytogenes if the typing procedure is standardized. The stability of the REA-types needs further elucidation in order to establish firm differentiation criteria for comparison of isolates.

0 Bookmarks
 · 
53 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The multiple-locus variable-number tandem-repeats analysis (MLVA) method for genotyping has proven to be a fast and reliable typing tool in several bacterial species. MLVA is in our laboratory the routine typing method for Salmonella enterica subsp. enterica serovar Typhimurium and Escherichia coli O157. The gram-positive bacteria Listeria monocytogenes, while not isolated as frequent as S. Typhimurium and E. coli, causes severe illness with an overall mortality rate of 30%. Thus, it is important that any outbreak of this pathogen is detected early and a fast trace to the source can be performed. In view of this, we have used the information provided by two fully sequenced L. monocytogenes strains to develop a MLVA assay coupled with high-resolution capillary electrophoresis and compared it to pulsed-field gel electrophoresis (PFGE) in two sets of isolates, one Norwegian (79 isolates) and one Swedish (61 isolates) set. The MLVA assay could resolve all of the L. monocytogenes serotypes tested, and was slightly more discriminatory than PFGE for the Norwegian isolates (28 MLVA profiles and 24 PFGE profiles) and opposite for the Swedish isolates (42 MLVA profiles and 43 PFGE profiles).
    Journal of Microbiological Methods 03/2008; 72(2):141-8. · 2.16 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Large epidemics of diarrhoea associated with seafood consumption and Vibrio parahaemolyticus occurred during the austral summers of 2004 and 2005 in the environs of Puerto Montt, Chile (41 degrees 29'S 72 degrees 24'W). There are no reports of V. parahaemolyticus infections before 2004 in this region, their absence being explained by the low ocean temperatures which seldom reach 16 degrees C. We analysed V. parahaemolyticus obtained from shellfish and clinical samples during epidemics. Isolates were examined using conventional protocols and an improved method for restriction enzyme analysis using total bacterial DNA which permits direct genome restriction enzyme analysis by conventional gel electrophoresis (DGREA) with a similar discrimination index as restriction fragment length polymorphism-pulsed field gel electrophoresis (RFLP-PFGE). Analysis of clinical samples showed that the epidemics were caused by the V. parahaemolyticus O3:K6 pandemic clonal group. On the other hand, analysis of shellfish samples during both epidemics showed that 53% contained V. parahaemolyticus (3-93 g(-1)). Detailed analysis of 50 positive shellfish samples showed that only three contained detectable levels of the pandemic clone. Most V. parahaemolyticus isolates obtained from shellfish corresponded to non-pandemic clones differentiated into 14 groups by DGREA. In summary, the causative agent during epidemics was only a minor component of a small but diverse population of V. parahaemolyticus in shellfish.
    Environmental Microbiology 05/2006; 8(4):675-83. · 5.76 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Large epidemics of diarrhoea associated with seafood consumption and Vibrio parahaemolyticus occurred during the austral summers of 2004 and 2005 in the environs of Puerto Montt, Chile (41 ° ° ° ° 29 ′ ′ ′ ′ S 72 ° ° ° ° 24 ′ ′ ′ ′ W). There are no reports of V. parahaemolyticus infections before 2004 in this region, their absence being explained by the low ocean temperatures which seldom reach 16 ° ° ° ° C. We analysed V. parahaemolyticus obtained from shellfish and clinical samples during epidemics. Isolates were examined using con-ventional protocols and an improved method for restriction enzyme analysis using total bacterial DNA which permits direct genome restriction enzyme anal-ysis by conventional gel electrophoresis (DGREA) with a similar discrimination index as restriction frag-ment length polymorphism-pulsed field gel electro-phoresis (RFLP-PFGE). Analysis of clinical samples showed that the epidemics were caused by the V. parahaemolyticus O3:K6 pandemic clonal group. On the other hand, analysis of shellfish samples dur-ing both epidemics showed that 53% contained V. parahaemolyticus (3–93 g − − − − 1). Detailed analysis of 50 positive shellfish samples showed that only three contained detectable levels of the pandemic clone. Most V. parahaemolyticus isolates obtained from shellfish corresponded to non-pandemic clones dif-ferentiated into 14 groups by DGREA. In summary, the causative agent during epidemics was only a minor component of a small but diverse population of V. parahaemolyticus in shellfish.
    · 5.76 Impact Factor