Characterization of serovars and drug resistance of Salmonella contaminating pork production chains in China, 2008-2023

ObjectiveTo systematically analyze the serovars and drug resistance characteristics of Salmonella contaminated with pork production chain in China from 2008 to 2023 based on literature.MethodsThe literature related to Salmonella in the pork production chain in China published from 2008 to 2023 was searched in China Knowledge and PubMed databases and 83 articles were screened. The data were statistically analyzed by using SPSS and Excel. According to time span， the literature were divided into three time periods： T1 （2008-2012）， T2 （2013—2017） and T3 （2018—2023） and were analyzed in comparison with the European Union and the United States homologous data on serovars and antimicrobial susceptibility.ResultsThe average positivity rate of Salmonella contamination in pork production chains in China from 2008 to 2023 was 18.0%， with higher positivity rates in both the slaughter （19.6%） and retail （29.1%） segments than in the farmed segment （8.4%）， which was much higher than that in the EU （slaughter： 1.4%； retail： 1.7%） and the United States （slaughter： 15.9%； retail： 1.4%） （P<0.05）. The most common serovars of Salmonella of pork origin in China were Samonella Derby （28.4%）， Samonella Typhimurium and Samonella I 4，［5］，12：i：- （24.7%） and Samonella Rissen （12.9%） and the rate of contamination varied over time： a gradual decrease in Derby， and a gradual increase in Samonella Typhimurium and S. I 4，［5］，12：i：- and Samonella Rissen. Five Salmonella of swine origin （Samonella Derby， Samonella Typhimurium and Samonella I 4，［5］，12：i：-， Salmonella Enteritidis， Samonella london and Samonella Rissen） had high rates of resistance to antimicrobial drugs such as doxycycline （85.1%）， tetracycline （78.8%）， ampicillin （65.1%） and chloramphenicol （61.5%） and were significantly higher than those in the EU and the USA （P<0.05）. The resistance rates of ampicillin， cotrimoxazole， tetracycline and ciprofloxacin showed an increasing trend with time， increasing by 38.3%， 28.2%， 18.0% and 15.1%， respectively.ConclusionThe contamination rate of Salmonella from pork sources in China was high， there was an elimination of some dominant serovars. The resistance rate of tetracycline antimicrobials showed an increasing trend in the whole. It is recommended to strengthen the regulation of the use of veterinary antimicrobial drugs in the pork production chain.