Veterinary-Susceptibility-Testing-BSAC-The-British-Society-獸醫(yī)藥敏試驗-BSAC的英國社會課件

1、Veterinary Susceptibility Testing.Chris Teale,Veterinary Laboratories Agency.Veterinary Susceptibility TestVeterinary-Susceptibility-Testing-BSAC-The-British-Society-獸醫(yī)藥敏試驗-BSAC的英國社會課件Key Surveillance Objective.Provide information of value in formulating sound policy to limit the development of resi

2、stance in bacteria of animal origin and to control the spread of antimicrobial resistance within the animal population and to man.Key Surveillance Objective.ProSurveillance for AntimicrobialResistance at VLASalmonella entericaVeterinary Clinical DiagnosticSubmissions Abattoir Surveillance for Zoonot

3、ic and Indicator Organisms.3 main areas of activity:Surveillance for AntimicrobialSalmonella entericaSalmonella isolates are tested against a panel of 16 antimicrobials by disc diffusion test.Results are reported annually.Isolates originate from veterinary clinical submissions, the abattoir surveys

4、of animals at the point of slaughter and from private laboratories (who are required to submit isolates for testing under statute - the Zoonoses Order).Salmonella entericaSalmonella Surveillance for Antimicrobial Resistance in Salmonella.Ciprofloxacin MIC is performed on all isolates that are resist

5、ant to nalidixic acid in the disc diffusion test.Ceftriaxone (or other third generation cephalosporin) MICs are performed on all isolates that are resistant to either ceftazidime or cefotaxime.Surveillance for AntimicrobialSurveillance of Veterinary Clinical Submissions at Regional Diagnostic Labora

6、tories.The VLA has 14 Regional Laboratories that are strategically located throughout England and Wales, ensuring coverage of all regions of these countries.Surveillance is achieved through incoming carcase material and specimens.Susceptibility testing is provided as part of the laboratory diagnosti

7、c service. In general, disc diffusion testing is performed.Surveillance of Veterinary CliVeterinary Clinical Submissions.A system has been put in place to collect all of the susceptibility data from tests performed at the Regional Laboratories and this is published annually on the Defra web-site(htt

8、p:/defraweb/animalh/diseases/zoonoses/index.htm)Veterinary Clinical SubmissionStatistically-based Surveillance at Abattoirs.This is essential to complement clinical surveillance, in particular for organisms such as Campylobacter, Enterococcus and E.coli O157, commensal E.coli, both for prevalence st

9、udies and to assess the antimicrobial resistance of these organisms.Abattoir surveys on pigs, sheep and cattle were performed in 1999/2000 in Great Britain; these are currently being repeated.Statistically-based SurveillanHarmonisation of Methods.Key objective is harmonisation of medical and veterin

10、ary susceptibility testing within the UK.Secondary objective is harmonisation at the international level. A network of all EU veterinary laboratories is taking this forward within the EU.The first joint medical/ veterinary resistance report covering a range of organisms isolated in 2002 has been pre

11、pared by HPA/VLA.Harmonisation of Methods.KeyDisc Diffusion Test.Currently used in most UK veterinary laboratories.Cut-off zone diameter of 13mm used to discriminate between sensitive and resistant strains.British Society for Antimicrobial Chemotherapy method is being adopted at VLA. Automated zone

12、readers being introduced to allow full implementation.Disc Diffusion Test.Currently Resistance Monitoring at VLA.Disc diffusion test.Panels of 8 antimicrobials (6 fixed; 2 selected at each Centre) appropriate for animal species and Gram-reaction of organism.Results (S/R) entered into Access database

13、, which both generates practitioner report and saves data.All databases combined and summary data produced annually at VLA Shrewsbury.Resistance Monitoring at VLA.DDisc Diffusion Methods (1)NCCLSUS Standard.Confluent inoculumData for some veterinary pathogens availableMueller-HintonUsed in some Scot

14、tish laboratories.Disc Diffusion Methods (1)NCCLDisc Diffusion Methods (2)BSACIsosensitest agarSemi-confluent inoculum (nudging colonies)UK standard methodCurrently no specific veterinary guidelinesHarmonisation with medical colleaguesDisc Diffusion Methods (2)BSACDisc diffusion test -Stokes method.

15、Disc diffusion test -Stokes meWhy is zone size determination useful?Early detection of trends in the emergence of resistance.Elucidation of mechanisms of resistance (and interpretative reading).Linkage of zone size to mic dataImprove Quality ControlEstablishment of robust breakpoints.Why is zone siz

16、e determinationThe relationship between Zone Diameter and MIC.Zone DiameterLog MICThe relationship between Zone The relationship between Zone Diameter and MIC.Zone DiameterLog MICConcentration reached in animal.The relationship between Zone The relationship between Zone Diameter and MIC.Zone Diamete

17、rLog MICConcentration reached in animal.Appropriate Zone Diameter.The relationship between Zone Potential Problems.No breakpoint zone size data available for some veterinary antimicrobials when using Isosensitest agar.Tissue concentration may differ betweenDifferent speciesDifferent sites in same an

18、imal (eg udder and serum in dairy cattle)Potential Problems.No breakpoiTotal Numbers of Isolates Examined by VLA.Total Numbers of Isolates ExamResistance in E. coli from Pigs, 1 month old.Resistance in E. coli from PigVeterinary-Susceptibility-Testing-BSAC-The-British-Society-獸醫(yī)藥敏試驗-BSAC的英國社會課件Salmo

19、nella spp. -ampicillin.BSAC breakpoint R or = 17mmSalmonella spp. -ampicillin.BSThe relationship between Zone Diameter and MIC.Zone DiameterLog MICThe relationship between Zone Veterinary-Susceptibility-Testing-BSAC-The-British-Society-獸醫(yī)藥敏試驗-BSAC的英國社會課件Surveillance Outputs.“Salmonella in Livestock”

20、 publication, produced annually gives details of resistance in salmonella.Annual Antimicrobial Sensitivity Report -published on the DEFRA web-site.Reports to practitioners -therapeutic panels of antimicrobials and the expanded salmonella surveillance sensitivity test.Reports of abattoir surveillance

21、 (usually announced at public meetings).Surveillance Outputs.“SalmoneImproving Surveillance Data Quality.Expert rules systemHarmonisation ring trials.Improving Surveillance Data QuExpert Rules System (1).Alert that an isolate has been recovered to manager of antimicrobial resistance sub-programme.Re

22、gional laboratory advised to check result and bacterial identification.Isolate retained in bead culture collection.Expert Rules System (1).Alert Expert Rules System (2).Streptococcus spp. any resistance to penicillin, ampicillin or amoxycillin/ clavulanate.Actinobacillus pleuropneumonia any resistan

23、ce to penicillin, ampicillin, ceftiofur or enrofloxacin.Salmonella enterica resistance to enrofloxacin.Expert Rules System (2).StreptHarmonisation Ring Trial Salmonella enterica.100% concordance between reference laboratories for:AmpicillinChloramphenicolApramycin (tested at 4/5 laboratories)Tetracy

24、clinesTrimethoprim/ sulphonamidesNeomycin.Harmonisation Ring Trial SalmoHarmonisation Ring Trial Salmonella enterica.There is a need for further work in some areas (in particular furazolidone, streptomycin and cefotaxime). Harmonisation Ring Trial SalmoHarmonisation Ring Trial Campylobacter spp.Thre

25、e participating laboratories.Good concordance for nalidixic acid and erythromycin.Concordance was less good for ciprofloxacin.Harmonisation Ring Trial CampyLinkage of resistance genes.E.faecium plasmid.Erythromycin resistance geneVancomycin resistance geneCopper resistance gene.Linkage of resistance

26、 genes.E.Organisms of Particular Concern in Agriculture from the Veterinary Perspective.Brachyspira hyodysenteriae (Swine dysentery)Multi-resistant Salmonella entericaResistance to third generation cephalosporins in Salmonella entericaOrganisms of Particular ConcerThe Spread of Resistance Genes and

27、Resistant Organisms.ANIMALS TO MAN:Apramycin/ Gentamicin resistance gene (AAC(3)IV) in Salmonella Typhimurium.MAN TO ANIMALS:Gentamicin resistance gene (AAC(3)II) in Salmonella TyphimuriumThe Spread of Resistance GenesJoint HPA/ VLA Study on Resistance in Salmonella enterica.Levels of resistance com

28、pared in serotypes Typhimurium, Enteritidis, Hadar and Virchow in man and animals in 2000.Joint HPA/ VLA Study on ResistThe Problem:The relative contribution of resistance in animal salmonella to the overall problem of resistance in human salmonella strains remains unquantified.The Problem:The relat

29、ive contrMethods.PHLS breakpoint method on agarVLA disc diffusion methodKanamycin and neomycin assumed to be equivalent.Nalidixic acid and low-level ciprofloxacin resistance considered to be directly comparable.Methods.PHLS breakpoint methodSalmonella Typhimurium.Of the four serotypes examined, resi

30、stance was most common in Salmonella Typhimurium from animals and man, with definitive phage types 104, 193, 208 and U302 in particular showing resistance.Multi-resistant strains of DT 208 appear to be associated with pigs; for other DTs the relationship between animals and man was complex.Salmonell

31、a Typhimurium.Of the Salmonella Enteritidis, Virchow and Hadar.Substantial differences in the resistance spectra of a significant proportion of isolates from humans and food-producing animals.Suggests that food-producing animals in England and Wales are not the primary source of these strains.Salmon

32、ella Enteritidis, VirchoOverall Levels of Resistance:Overall Levels of Resistance:Main Serotypes in Man and Animals in 2000:Enteritidis (8,468)Typhimurium (2,424)Hadar (348)Virchow (309)Dublin (697)Typhimurium (602)Senftenberg (269)Give (148)MANANIMALSMain Serotypes in Man and AnimSalmonella Enterit

33、idisCases in man have declined since 1997, though it remained the most common serotype in 2000.14% of poultry isolates resistant to furazolidone (67% in France in 1999); 1% human isolates resistant to furazolidone.5% of animal (poultry) isolates resistant to nalidixic acid; 11% of human isolates res

34、istant.Salmonella EnteritidisCases inS.Virchow78% Isolates from man resistant to one or more antimicrobials.21% Isolates from poultry resistant to one or more antimicrobials.S.Virchow78% Isolates from manResistance to Nalidixic acid in S.Virchow in France.60.3% of Salmonella Virchow isolates of poul

35、try origin from France in 1999 were resistant to nalidixic acid.N.B. Data not available for many countries.Resistance to Nalidixic acid iSalmonella HadarS. Hadar isolated only from poultry and man.48% of human isolates and 54% of poultry isolates resistant to nalidixic acid In most cases, resistance detected in poultry isolates to certai