Title Molecular Typing of Listeria monocytogenes, an approach for Tracing Contaminations
Call Number TS 212
Author(s) Moordiani - Personal Name
Subject(s) Mikrobiologi
Series Title
GMD Text
Language English
Publisher School of Bioscience The University of Nottingham
Publishing Year 2012
Publishing Place Nottingham
Abstract/Notes Abstract

Listeria monocytogenes is a Gram positive rod-shape bacteria. Unlike most other foodborne pathogens that it only rarely cause the typical symptoms of gastroenteritis, Listeria monocytogenes infection may result in more serious symptoms, usually take the form of meningitis or septicaemia. Those with immune system are vulnerable are in a bigger risk of got the infection. Crucially, it also tougher than any other bacteria found in the food, with more resistant to heat, drying, or salty environment. These give Listeria monocytogenes more difficult to be vanished.
This study is purposed to identify and trace Listeria monocytogenes contamination in a fresh cut factory using molecular typing methods. Firstly, the isolate sample was identified and confirmed as a Listeria monocytogenes. The methods used in this step were Gram staining, tumbling motility test, catalase test and haemolysin assay. After that, together with other Listeria monocytogenes isolates obtained from the different place, the factory sample was typed. The methods used were speciation, allele-specific oligonucleotide, serotyping and ribotyping PCR, and pulsed-field gel electrophoresis.
The identification tests showed that LM 25722248 sample is Listeria monocytogenes, confirmed by a positive result for Gram staining (it is a Gram positive bacterium), tumbling motility and catalase tests, and haemolysin assay. Using speciation PCR, sample was able to show specificity for Listeria monocytogenes. With allele-specific oligonucleotide and serotyping PCR methods, LM 25722248 sample was identified belongs to lineage 2 and of serovar 1/2a, respectively. In combination between PFGE and ribotyping, it was verified that LM 25722248 sample is different with other Listeria monocytogenes isolates obtained from the laboratory which was originally came from other places hence assumed to be different.
It can be concluded that the techniques performed above are reproducible to carry out a molecular typing to LM 25722248 sample. In addition, making comparisons of LM 25722248 sample with other samples gained from the same factory using combination of molecular techniques mentioned before could clarify the similarity, and the origin, of the samples.
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