| ObjectiveEscherichia coli is widely found in nature,and in most cases it is found in human and animal.Now,Escherichia coli is one of the important indicators of antibiotic resistance in livestock and poultry.Salmonella is an important public health zoonosis of serotypes found as many as two thousand kinds of current.In animals,chickens are the main source of Salmonella infection,which can cause death in severe cases.S.aureus is the natural distribution of the most extensive pyogenic bacteria of human or animal,can cause local abscess,sepsis,sepsis etc..In recent years,in order to prevent and treat the bacterial diseases,and promote the development and growth of animals,a large number of antimicrobial agents used in intensive farms or individual farmers.The use of antibacterial drugs of long-term and extensive and unreasonable,and antibiotic selection pressure to E.coli,Salmonella and S.aureus resistant strains increase,resistance spectrum expanded,even some strains have not been used for new antibacterial drugs in clinical treatment also showed resistance.Chloramphenicol antibiotics are a broad spectrum of antibiotics,due to the strong toxicity of chloramphenicol,in 2002,chloramphenicol was listed as a banned drug in China,Florfenicol is widely used as a new generation of chloramphenicol antimicrobial agents in animal bacterial diseases.Therefore,the distribution characteristics of animal source E.coli,Salmonella and S.aureus resistant strains of the epidemic situation,the resistant phenotype and Chloramphenicols resistance genes,and the correlation analysis between,will have a positive significance for clinical veterinary and public health,to curb the development of E.coli,Salmonella and drug resistance of S.aureus,has important significance to guide the clinical medication,lay the foundation for further study on chloramphenicol antibacterial drug resistance mechanisms.MethodsThis study from September 2014 to March 2016,in Beibei District of Chongqing,Hechuan District,Rongchang District and Dianjiang District and other places of 13 farms(households)were respectively collected E.coli,Salmonella and Staphylococcus aureus samples,The Escherichia coli,Salmonella and Staphylococcus aureus were isolated and identified by Gram staining,morphological features,and PCR methods.To determine the sensitivity of E.coli,Salmonella and S.aureus of 30 kinds of antimicrobial agents by Disk diffusion method.Then the PCR technology was used to detect the resistance genes of chloramphenicols,such as flor,clmA,fexA,fexB,cat,pexA,and cfr,in E.coli,Salmonella and S.aureus.To analyze the relationship between the resistance phenotype and the resistance genotype of all the strains.ResultsFinally,in the part of Chongqing city Beibei District,Hechuan District,Rongchang district and Dianjiang county area,1003 samples were collected from E.coli,695 strains of E.coli,isolation rate was 69.3%,of which 393 strains of swine,chickens,194 strains of 108 strains of bovine origin;867 samples were collected from Salmonella,66 strains of Salmonella,isolation rate was 7.6%,of which 31 strains of swine,chickens,26 strains of 9 strains of bovine origin;926 samples were collected from S.aureus,103 strains of Salmonella,isolation rate was 11.1%,of which 64 strains of swine,chickens,29 strains of 7 strains of bovine origin;The total number of strains was 864.The results of drug sensitivity showed that E.coli,Salmonella and S.aureus showed different resistance to 30 kinds of antibiotics.The average resistance of E.coli was 6.2%~91.4% among E.coli to penicillin G,ampicillin,amoxicillin,vancomycin resistance rate of more than 70%;of ofloxacin and Amikacin resistance rate below 20%.The average resistance of Salmonella was 9.1%~100.0%,Salmonella to penicillin G,amoxicillin,ampicillin,vancomycin resistance rate was above 85%;resistant to levofloxacin,ceftazidime and amikacin was below 20%.S.aureus in average resistance rate was between 12.6%~79.6%,S.aureus resistance rate is more than 70% of penicillin G,ampicillin,amoxicillin,Lin;to ceftazidime,cefazolin,cefoperazone,ceftriaxone,cephalexin,gentamicin,amikacin resistance rate does not exceed 20%.E.coli,Salmonella and S.aureus showed varying degrees of multidrug resistance,Multi drug resistant E.coli was the highest 29 resistant strains in 2 strains,a minimum of 0 resistant strains and 1 strains of Salmonella;multidrug resistance was the highest 27 resistant strains of 1,a minimum of 4 resistant strains and 1 strains of S.aureus;multidrug resistance was the highest 25 resistant strains in 1 strains,2 minimum resistance the results showed that 3 strains.From different regions collected from E.coli to 30 kinds of antimicrobial resistance rates,resistance of Dianjiang county was generally higher than that of Beibei District,Hechuan district and Rongchang district;Different areas of Salmonella showed different resistance to different antibiotics;Drug resistance of Staphylococcus aureus,Beibei District,Hechuan District,generally lower than the rate of Rongchang district and Dianjiang county.The drug resistance rate of E.coli from different animal sources,chicken source is generally higher that of porcine,pig source is generally higher than bovine origin;The distribution of drug resistance of Salmonella from different animal sources was similar to that of E.coli.Chicken was the highest,the second was the source of pig,and the lowest was bovine origin;Different animal origin of S.aureus,in addition to the individual antibiotics of bovine and rabbit was slightly high,chicken source resistance rate is generally higher than other animals.The resistance rate of E.coli in different seasons,rate of spring was higher than that in summer,and the resistance rate in autumn was higher than that in summer;The resistance rate of most antibiotics in Salmonella was 100%,there was no significant difference in summer,autumn and winter.Resistance gene electrophoresis results showed that,408 strains of flor gene were detected in 695 strains of E.coli,the detection rate was 58.7%,403 strains of clmA gene,the detection rate was 58.0%;257 strains of cat gene,the detection rate was 37.0%;6 strains of cfr gene,the detection rate was 0.9%.45 strains of flor gene were detected in 66 strains of Salmonella,the detection rate was 68.2%;clmA gene 41 strains,the detection rate was 62.1%;cat gene 52 strains,the detection rate was 78.8%,2 strains of cfr gene,the detection rate was 3%.S.aureus was detected in the flor gene of 28 strains,the detection rate was 27.2%,clmA gene of 33 strains,the detection rate was 32%,cat gene of 45 strains,the detection rate was 43.7%,cfr gene of 1 strains,the detection rate was 1%,fex A gene of 43 strains,the detection rate of 41.7%.FexB and pexA were not detected.E.coli,Salmonella and S.aureus detection of drug resistance genes of the drug resistance phenotype and drug resistance genotype coincidence rate of more than 50%,the number of bacterial strains with 356 strains of E.coli,the coincidence rate was 59.6%;the number of bacterial strains of Salmonella with 58 strains,the coincidence rate was 93.5%;the number of bacterial strains of Staphylococcus aureus strains was 51,the coincidence rate is 67.1%.E.coli,Salmonella and S.aureus was not detected in resistant phenotype and genotype drug resistance genes in isolates with the rate of E.coli strains,which accord with the 68 strains,the coincidence rate was 69.4%;the number of Salmonella bacteria with 2 strains,the coincidence rate was 50%;Strains of S.aureus with 9 strains,the coincidence rate is 33.3%.ConclusionThe sampling time of this strain was from September 2014 to March 2016,Respectively,from Chongqing Beibei District Beilong company slaughterhouse,Chongqing mayor waterfowl Industry Development Co.,Ltd.,Chongqing Hechuan District dairy farmers Chen Zhaoqiang and Chongqing Rongchang District "Chongqing pig farm" and so on 13 farms collected E.coli,Salmonella and Staphylococcus aureus strains.The isolation rate of E.coli was 69.3%,the separation rate of Salmonella was 7.6%,and the isolation rate of S.aureus was 11.1%.E.coli,salmonella and S.aureus on 30 kinds of antibacterial drugs showed different degree of drug resistance,most of the strains exist the phenomenon of multiple drug resistance.Among them,penicillin G,ampicillin,amoxicillin and vancomycin were the most resistant,and the resistance rate was higher than 70%;The resistance rate to Amikacin was lower than 20%,which was more sensitive to Amikacin.The detection rates of flor,clmA and cat genes were relatively high in E.coli,Salmonella and S.aureus,which,clmA for the 3 types of bacteria strains carrying the most resistant gene.The fexB and pexA genes were not detected in this study.E.coli,salmonella and S.aureus detected strains of drug-resistant genes and its coincidence rate of drug resistance phenotypes,or not detected strains of drug-resistant genes and its coincidence rate of drug resistance phenotypes were both not up to 100.0%. |
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