Prevalence of Listeria monocytogenes in Raw Meats Marketed in Bangkok and Characterization of the Isolates by Phenotypic and Molecular Methods.
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Date
2011-02
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Abstract
Listeria monocytogenes causes listeriosis characterized by septicaemia, encephalitis, and abortion or stillbirth.
Regular monitoring of its prevalence in food and characterization of its phenotypes and genotypes
are necessary for disease surveillance and tracing the epidemic outbreaks. In this study, the prevalence of
L. monocytogenes in raw meats marketed in Bangkok was 15.4%. The bacteria isolated from meat were serotyped
and genotyped using enterobacterial repetitive intergenic consensus–polymerase chain reaction
(ERIC-PCR). Their virulence-associated genes, antimicrobial susceptibility, and ability to invade intestinal
epithelial cells were studied. All 22 L. monocytogenes strains isolated from 104 raw meat samples carried
virulence-associated genes, such as actA, flaA, hlyA, iap, inlA, inlB, and prfA. These were serotype 4b, suggesting
their pathogenic and epidemic potential. These isolates could be classified into six ERIC-PCR groups:
A-F. The majority (59.1%) of the isolates belonged to Group A, and three isolates were Group D which was
closely related to the Group A. Two isolates each were Group C and E, and one isolate each was group B
and F. Although the isolates belonged to the same serotype and genotype and were all equipped with the
virulence-associated genes, they showed a different cell invasion capability and antibiotic susceptibility. All
the isolates were susceptible to ampicillin, amikacin, chloramphenicol, gentamicin, imipenem, penicillin
G, sulphamethoxazole-trimethoprim, and tetracycline. However, one isolate showed only intermediate
susceptibility to tetracycline. The data provide the first molecular insight into the L. monocytogenes isolates
in Thailand and elucidate a potential risk of people contracting listeriosis.
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Keywords
Characterization, Phenotype, Flagellin, Genes typing, Haemolysin, Internalins, Invasins, Listeria monocytogenes, Listeriolysin, Listeriosis, Microbial sensitivity tests, Virulence genes, Thailand
Citation
Indrawattana Nitaya, Nibaddhasobon Tanaporn, Sookrung Nitat, Chongsa-nguan Manas, Tungtrongchitr Anchalee, Makino Sou-ichi, Tungyong Witawat, Chaicumpa Wanpen. Prevalence of Listeria monocytogenes in Raw Meats Marketed in Bangkok and Characterization of the Isolates by Phenotypic and Molecular Methods. Journal of Health, Population and Nutrition. 2011 Feb; 29(1): 26-38.