Detection Of Antibiotic Resistance Genes In Cheese Products And Identification Of Multi-drug Resistance Of Isolated Cheese Bacteria

At present,different types of antibiotics are widely used in clinical and animal breeding,leading to the emergence of multi-drug resistant bacteria.Bacterial antibiotic resistance is caused by antibiotic resistance genes,which persist in soil and water environments and have been identified as novel pollutant.In addition,the enrichment of resistance genes in food can have more direct effects on human health,As a ready-to-eat food,cheese is becoming increasingly popular in the China,because of the unique taste and flavor,In the process of making cheese,many fermentation bacteria are added to produce acid.In addition to the fermentation bacteria,there are also some unique non-fermentation bacteria.Consequently,the microbial diversity in cheese is rich.However,at present,there are few studies on the existence of antibiotic resistance genes.Therefore,quantitative PCR(QPCR)was used to detect the resistance genes of 8 categories of antibiotics(Beta Lactam,Aminoglycoside,Tetracycline,FCA,MLSB(Macrolide-Lincosami de-Streptogramin B,Vancomycin,Sulfonamide,others)in 23 popular cheeses on the domestic market,and the bacterial diversity in these cheeses and the multi-drug resistance of dominant bacteria in cheese were analyzed.The results showed that,except vancomycin resistance genes,the resistance genes of other 7 categories of antibiotics could be detected by high abundance in cheese samples,A total of 223 ARGs were detected in 17 cheese samples,and 52 ARGs were detected in 6 remanufactured cheese samples.Aminoglycosides(17.5%)and tetracycline(12%)were the top two detection rates of antibiotic resistance genes in reprocessed cheese,while FCA(56%)and aminoglycosides(52%)were the top two detection rates of antibiotic resistance genes in natural cheese.while the abundance of resistance genes in reprocessed cheese made from natural cheese was significantly lower than that of natural cheese.High throughput sequencing was used to analyze the microbial diversity in cheese,The results showed that all kinds of cheese fermentation bacteria belong to Lactococcus,Streptococcus,Lactobacillus of firmicutes.and Propionibacterium of actinomycetes,Citrobacter of proteobacteria.Twenty-five strains of different types of bacteria were isolated from different cheese.To further indentify the existence of highly abundant resistance genes detected by QPCR in cheese,the corresponding antibiotics were used to characterize drug resistances within the 25 isolated bacteria respectively,and the results indicated that the isolated bacteria possess multiple drug resistance.The first two drugs with high drug resistance rate in all bacteria were sulfamethoxazole(95%)kanamycin(85%),and the first two drugs with high sensitivity rate were ampicillin(95%)tetracycline(85%),respectively,and it was generally shown that antibiotic-related resistance genes of drug resistance could be detected in bacteria in high abundance.In summary,although most live bacteria in cheese are probiotic,it is a ready-to-eat food possessing drug resistance.As the result,with the increasing consumption of cheese in China,sufficient attention should be paid to the detection of drug resistance genes as well as the drug resistance bacteria.