Contamination status, multilocus sequence typing, and drug resistance of Salmonella in poultry meat in Liaoning Province

Abstract:

[Background] Salmonella is a major group of zoonosis pathogens that can be transmitted to humans through poultry and its products, posing a threat to human health. It is important for public health to understand the pathogenic characteristics and drug resistance of Salmonella in poultry meat. [Objective] To investigate the contamination status, serotype distribution, drug sensitivity, and molecular epidemic characteristics of Salmonella in poultry meat sold in Liaoning Province in 2022, and to explore the relationship between different serotypes, multilocus sequence typing (MLST) results, and drug resistance. [Methods] The collected samples were tested according to the method in the National Standard for Food Safety: Microbiology Inspection of Salmonella (GB 4789.4—2016), and the strains were identified by biochemical tests. The slide agglutination method was used for the serological test, and the micro-broth method was employed to examine the drug sensitivity of the strains. BioNumerics 7.6 was used to analyze the results of drug sensitivity tests and MLST. [Results] The 53 Salmonella strains belonged to 11 serotypes, mainly S. enteritidis. The resistance rate of Salmonella to nalidixic acid (NAL) was the highest, 92.5% (49/53). A total of 25 multiple drug resistance spectra were identified, and the total resistance rate was 66.0% (35/53). Among the drug resistance genes, the tetracycline resistance gene tetC showed the highest carrying rate of 45.3% (24/53). The strains of Salmonella were classified into 10 sequence types (STs) and 1 unclassified type according to the sequences of 7 housekeeping genes. [Conclusion] The Salmonella in poultry meat sold in Liaoning Province demonstrates serious contamination, with diverse serotypes, high overall drug resistance, and serious multidrug resistance. Efforts should be doubled for the standardization of poultry breeding.