Research On Isolation,Identification And Phenotypic Resistance Analysis Of Salmonella From Row Chicken Meat In Ya'an City

Salmonella is the most common foodborne pathogen that causes intestinal diseases in humans after food transmission.According to the data,food-borne diseases caused by Salmonella infection have long occupied the top of the world,and Salmonella is the culprit in the outbreak of food-borne diseases in China.In order to prevent and treat salmonellosis,an effective measure commonly used is the antibiotics.However,long-term low-dose induction of antibiotics has increased the drug resistance of Salmonella,and the drug resistance spectrum has been broadened.This not only brings great resistance to the prevention and treatment of salmonellosis,but also poses a threat to social public health security.As a natural host of Salmonella,chicken is one of the main sources of transmission of human Salmonella infection.However,chicken is an indispensable dish on the table of the common people.Therefore,knowing the situation of fresh chicken meat contaminated with Salmonella,studying the distribution of Salmonella serotypes and analyzing its phenotypic resistance is an important prerequisite for effective prevention and control of the spread of salmonellosis,and also provides a reference for regulating the use of antibiotics.The main contents are as follows:1.Isolation and identification of Salmonella in fresh chicken meat in Ya'an CityIn this study,240 fresh chicken meat samples were collected from 48 supermarkets,farmers'markets,and vendors in Ya'an City.BPW medium was used to enhance the bacteria and selective enrichment was carried out on TTB medium and SC medium.Then,they were inoculated separately into XLD medium and BS medium,and 85 strains of suspected Salmonella were isolated after lysine decarboxylase and TSI slant medium.Biochemical identification and PCR identification of suspected Salmonella were carried out,and 74 strains were confirmed to be Salmonella finally.2.Serotyping of Salmonella in fresh chicken meat in Ya'an CityThe serotyping test of 74 strains of Salmonella was carried out by using Salmonella diagnostic serum and 16S rDNA Sequence Analysis.The results showed that there were 25strains in B group,accounting for 33.78%,including 16 strains?21.62%?of S.Typhimurium,7of S.Paratyphi B?9.46%?and 2 of S.Agona?2.7%?.There are 9 strains in C₁ group,accounting for 12.16%,including 6 strains of S.Thompson?8.1%?,3 strains of S.Braenderup?4.05%?.Besides,38 strains in D₁ group,accounting for 51.35%,including 25 strains of S.Enteritidis?33.78%?,13 strains of S.Gallinarum?17.57%?.What's more,S.Quebec has 2 strains?2.7%?.3.Analysis of phenotypic resistance of Salmonella in fresh chicken meat in Ya'an CityEight common antibiotics were selected,and phenotypic resistance of 74 strains of Salmonella were detected by K-B paper method and micro-broth dilution method.The results showed that 74 strains of Salmonella all showed different degrees of antibiotic resistance and the multi-drug resistance was 59.46%?44/74?.The resistance rate to Penicillin antibiotics?Ampicillin,Amoxicillin?were 64.86%⁷0.27%,to Aminoglycoside antibiotics?Gentamicin,Kanamycin?were 6.76%³7.83%,to Tetracycline antibiotics?Tetracycline,Minocycline?were 17.58%⁶7.57%,to Cephalosporin antibiotics?Ceftriaxone Sodium?was 10.81%and to Quinolone antibiotics?Nalidixic Acid?was 20.27%.The MIC₅₀ values were:Ampicillin was 2ug/mL,Amoxicillin was 2/1 ug/mL,Gentamicin was 4 ug/mL,Kanamycin was 8 ug/mL,Tetracycline was 4 ug/mL,Minocycline was 2 ug/mL,Ceftriaxone Sodium was 0.5 ug/mL and Nalidixic Acid was 8 ug/mL.In summary,this study used Ya'an fresh chicken meat as samples,by means of isolating and identificating Salmonella in samples,serotyping and analyzing phenotypic resistance,to know the contamination rate and serotype of Salmonella in raw chicken meat in this city.Distribution and antibiotic resistance provide basic data and references for research on controlling the spread of salmonellosis and the use of antibiotics in cultured chickens.The research results have certain theoretical and practical value.