Prevalence of Listeria monocytogenes in Raw Meats Marketed in Bangkok and Characterization of the Isolates by Phenotypic and Molecular Methods

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.

Bacterial Contamination in Retail Foods Purchased in Thailand

“…For example, the Thai government has established a policy to develop Thailand as the "Kitchen of the World". However, various types of spoilage and pathogenic bacteria have been found in Thai foods (Indrawattana et al, 2011;Keeratipibul et al, 2010;Minami et al, 2010;Padungtod et al, 2006;Suthienkul et al, 1990;Vindigni et al, 2007;Vuddhakul et al, 2000).…”

Polymerase chain reaction (PCR4)-based detection of hly and plc-A genes in Listeria monocytogenes isolated from dairy and meat products in Iran

“…The bacteria can grow under a wide range of temperature and external stress such as extreme pH and salt concentration, and these are thus, ubiquitous (Indrawattana and Nibaddhasobon, 2011). In recent years different epidemiological and experimental investigations revealed that contaminated food is an important route for transmission of bacteria to humans.…”

Prevalence of Campylobacter spp., Salmonella spp., Listeria monocytogenes, and Hepatitis E Virus in Swine Livers Collected at an Abattoir

“…Serotyping was performed by examining group-specific Listeria O and H antigens by slide agglutination using commercially prepared antisera (Denka Seiken). Nine virulence-associated genes (actA, clpE, hlyA, iap, inlA, inlB, plcA, plcB, and prfA) were investigated by PCR analysis (10,11).…”