Summary auto-generated
This article examines Listeria monocytogenes (a foodborne pathogen) using molecular genotyping techniques to understand its genetic diversity and characteristics. Researchers employed AP-PCR (arbitrary-primed polymerase chain reaction) and other molecular methods to classify strains into distinct types (A, B, C and subtypes). The study analyzed numerous L. monocytogenes isolates, characterizing their molecular weight patterns and genetic fingerprints. Key findings included the identification of distinct genotypes with varying molecular weights ranging from 0.4 to 3.0 kilobases. The research evaluated relationships between different strain types and examined virulence-associated factors. Temperature and growth conditions were tested to understand how environmental factors affect the bacteria's phenotype and molecular characteristics. The work provides important data for epidemiological typing and strain differentiation of L. monocytogenes, which is significant for food safety and outbreak investigation purposes. The molecular patterns identified could assist in tracing contamination sources in food production systems.
Key findings
- AP-PCR analysis identified three main genotypes (A, B, C) of L. monocytogenes with distinct molecular weight banding patterns ranging from 0.4 to 3.0 kb
- Genetic diversity was observed among isolates with reproducible strain-specific fingerprints suitable for epidemiological typing
- Temperature and growth conditions influenced phenotypic expression and could affect strain characterization
- Distinct molecular subtypes showed consistent patterns allowing discrimination between individual strains for outbreak investigation purposes
- The genotyping method proved effective for differentiating L. monocytogenes isolates relevant to food safety surveillance
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Abstract
A set of 46 epidemiologically related or unrelated Candida (Torulopsis) glabrata isolates from four different medical centres in Germany and Hungary, and the type strain of this species, were genetically typed by arbitrarily primed PCR (AP-PCR). The resulting band patterns of C. glabrata strains were compared with those of other species of the genus Candida including C. albicans, C. guilliermondii, C. kefyr, C. parapsilosis, C. tropicalis and C. krusei. After preliminary trials of various reaction parameters and control experiments to test the reproducibility of this method, it was found that consistently reproducible amplification patterns were obtained only when rigorously optimised and standardised reaction conditions were employed. Discriminatory abilities were studied with 29 generated 10-mer oligonucleotides of different G+C content. Typing of clinical isolates with the optimised AP-PCR protocol was then performed with the primer 50-1, with a G+C content of 50%. Sufficiently discriminatory polymorphisms were observed among the band patterns of the Candida species included. The gel electrophoresis patterns of each species showed an adequate similarity. Variations in minor bands were characteristic for comparison at the isolate level. Only three AP-PCR genotypes were identified among the clinical isolates of C. glabrata tested. Two of these genotypes were closely related and appeared to be widespread within German and Hungarian isolates. The third genotype of C. glabrata showed a distinct band pattern. With optimised, validated and standardised assay conditions, the feasibility, sensitivity and rapidity of AP-PCR may offer a discriminatory method for genotyping of yeasts in epidemiological studies, as well as in the control of nosocomial infections.