How do the Different Wet Market Areas Affect the Virulence of Salmonella Found in Fresh Chicken Wings?

Abstract:

This is a survey of fresh chicken wings from wet markets in Hong Kong that looks at the prevalence of Salmonella. As well as providing some indication of hygiene practices in wet markets, genomic sequencing and phylogenetic analysis can reveal relationships between Salmonella strains that may provide information about their origins.

Salmonella is a Gram-negative enteric bacterial pathogen of the family Enterobacteriaceae and typically lives in both human and animal intestines. The main concern related to Salmonella is that poultry meat, especially in chickens, is the most frequent source of food poisoning in humans, causing symptoms such as diarrhoea, fever, and nausea. The complete eradication of Salmonella from poultry products is an increasingly difficult task, especially in wet markets. This may be due to their lack of maintenance and poor sanitary practices in markets, but equally can also be a consequence of intensive farming and industrial processing. As wet markets in Hong Kong commonly sell fresh poultry products, including chicken wings, seafood, pigs, and even amphibians and reptiles, this study aims to characterise the virulence and antimicrobial resistance profiles of Salmonella found in chicken wings to understand more about the factors affecting its proliferation.

Six fresh chicken wing samples were collected from three different shops in two districts in Hong Kong. The samples were mixed in a saline buffer solution, serial-diluted, and incubated overnight at 37 ℃. The Salmonella colonies were then identified using CAS+ (CHROMagar Salmonella Plus), CAS (CHROMagar Salmonella), 3M™ Petrifilm™ E. coli/Coliform count plates, and LB agar plates. Isolates were streaked and passaged before DNA extraction. Genomic DNA was extracted using Invitrogen PureLink Genomic DNA Mini Kit and shotgun sequencing performed via the Illumina MiSeq platform.