Prevalence Of Foodborne Pathopgens In The Fresh Meats Of Nanning And Study On The Antimicrobial Resistance Of Salmonella Isolates

Salmonella spp,Escherichia coli O157:H7,Listeria monocytohenes and Campylobacter jejuni are the most important pathogens of foodborne diseases around the world,widespread in nature and mostly symbiotic bacteria or pathogens in animal intestinal tract.The main route of transmission of these pathogens to humans is through the consumption of polluted foods,and may result in vomiting,diarrhea and other food poisoning symptoms in patients,and that accounting for 90%of the foodborne bacterial poisoning incidence.The purpose of the study including:to investigate the prevalence of foodborne pathogens in the fresh meats in Nanning;to classify the serotypes of Salmonella isolates and evaluate the drug resistance phenotypes and to detect the drug resistant genes.According to the Chinese national standard method,the prevalence of four foodborne pathogens was determined by collecting and testing fresh meat samples including beef,pork,chicken and duck,in fifteen supermarkets and wet markets in Nanning,Guangxi during 2011-2012.Furthermore,the isolates of Salmonella were identified by serotyping and antibiotics resistance evaluations through both classical resistance phenotypes test against 20 common antibiotics and resistant genes detection by PCR technique.The results showed that in the fresh meats Salmonella spp.ranked the highest contamination(21%),then following by Lm(3.7%),C.jejuni(2.5%)and E.coli O157:H7(1.5%),and the samples from supermarkets were more detected than the samples from wet markets for the pathogens except C.jejuni and Lm even was just only detected in supermarkets;Salmonella was mostly detected in pork(35.6%)and then in duck(20.7%),E.coliO157:H7 was more likely detected in livestock than in poultry,while C.jejuni and Lm were found to be more detected in poultry than in livestock;166 Salmonella isolates were identified by serotype classification,the majority of isolates being classified as group B(49.4%,82/166),followed by group E1.Of all the 38 serotypes determined,S.Derby(n=60,36.1%)is dominated and the followings are S.London(n=15,9%),S.Newlands(n=8,4.8%)and S.Enteritiadis(n=7,4.2%);Salmonella isolates showed the strongest resistance to TET and relatively high to AMC and AMP.50.6%of Salmonella isolates were showed resistant to more than four antibiotics and the highest is resistant to 13 antibiotics.The most common resistant spectrum is AMP-CHL/TSU-TMP/AMC-TET;Three kinds of resistant genes against tetracycline,sulfonamides and chloramphenicols,and two against aminoglycosides,respectively were detected in Salmonella isolates.The results of the study demonstrated that the prevalence of four foodborne pathogens was polluting fresh meats in NanNing;the majority serotype of Salmonella isolates being classified as group B,and the dominant serotypes is S.Derby;the resistance of Salmonella isolates is more serious and the prevalence of drug resistance genes in Salmonella isolates.