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Recent Changes to the Recommendations Jenny Andrews.

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Presentation on theme: "Recent Changes to the Recommendations Jenny Andrews."— Presentation transcript:

1 Recent Changes to the Recommendations Jenny Andrews

2 Members of the BSAC Working Party on Susceptibility Testing Scientific Dr. D. Brown (Chairman & Secretary of EUCAST) Mrs. Andrews (Secretary) Miss. King Dr. Livermore Dr. Winstanley Dr. Perry Veterinary Service Mr. C. Teale Medical Professor MacGowan (President of the BSAC) Professor C. Gemmell Dr. N. Damani Dr. M. Dryden Dr. N. Brown Dr. G. Kahlmeter (SRGA & EUCAST) Industry Mr. P. Wheat (Mast) Mr. C. Booth (Oxoid)

3 Versions of the recommendations First publication in the BSAC Newsletter in the summer 1998 Publications in the JAC Supplement July 2001 Standardized disc method JAC May 2004 Website Version2 July August January August February May November January 2004 (current version)

4 BSAC website (www.bsac.org.uk) Site DirectoryAbout BSACAlliance for the Prudent Use of Antibiotics What’s onANNOUNCEMENTSAwards NewsBSAC Working Party Publications Consultations ResourcesConsumer SectionEducation Resource GuidesEvidence Based Medicine & Clinical Effectiveness External Contacts Garrod Medal & LectureGrants Programme DiscussionsJACMembership Grants & AwardsMiscMRSA JournalNational Prevalence Survey of MRSA Therapy Newsletter Past EventsPowerpoint Presentations PublicationsPUBMED Resistance SurveillanceSARS Susceptibility TestingWhat’s On

5 BSAC website (www.bsac.org.uk) Site directoryAbout BSACAlliance for prudent use of Antibiotics What’s onAnnouncementsAwards NewsBSAC Working Party Publications Consumer-section Resources Education ResourceEvidence Based Medicine & Clinical Effectiveness GuidesGarrod Medal & LectureGrants Programme External Contacts JACMembership DiscussionsMISCNational Prevalence Survey of MRSA Therapy Grants & AwardsNewsletterPast events JournalPowerPoint PresentationsPublications PUBMEDResistance Surveillance SARS What’s on Susceptibility Testing

6 BSAC Working Party on Susceptibility Testing Working Party membership and remit Susceptibility Testing News Background information on some of the recent updates to the BSAC Guidelines and issues currently under review Susceptibility Testing – Powerpoint presentations Powerpoint presentations from previous User Group Days User Group Day Reports Reports and question & answer sessions from previous User Group Days Residential Workshops & User Group Days Details of forthcoming events Guide to Antimicrobial Susceptibility Testing The complete guide to antimicrobial susceptibility testing (with links to individual chapters), based on the JAC Suppl 2001 BSAC Standardized Disc Susceptibility Testing Method Current method with previous versions and other additional methodology BSAC Disc Diffusion Template programme BSAC Standardized Method Development Centre

7 Guide to Antimicrobial Susceptibility Testing Chapter One: History and development of antimicrobial susceptibility testing Chapter Two: Determination of minimum inhibitory concentrations Chapter Three: Establishing MIC breakpoints and the interpretation of in vitro susceptibility tests Chapter Four: The development of the BSAC standardized method of disc diffusion testing Chapter Five: BSAC standardized disc susceptibility testing method Chapter Six: Detection of beta-lactamase-mediated resistance Chapter Seven: Detection of methicillin/oxacillin resistance in staphylococci Chapter Eight: Quality assurance of antimicrobial susceptibility testing by disc diffusion Chapter Nine: Recommendations for susceptibility tests on fastidious organisms and those requiring special handling Chapter Ten: Instrumentation in antimicrobial susceptibility testing Chapter Eleven: Interpretative reading: recognizing the unusual and inferring resistance mechanisms from resistance phenotypes

8 Resources - Susceptibility Testing BSAC Working Party on Susceptibility Testing Working Party membership and remit Susceptibility Testing News Background information on some of the recent updates to the BSAC Guidelines and issues currently under review Susceptibility Testing – Powerpoint presentations Powerpoint presentations from previous User Group Days User Group Day Reports Reports and question & answer sessions from previous User Group Days Residential Workshops & User Group Days Details of forthcoming events Guide to Antimicrobial Susceptibility Testing The complete guide to antimicrobial susceptibility testing (with links to individual chapters), based on the JAC Suppl 2001 BSAC Standardized Disc Susceptibility Testing Method Current method with previous versions and other additional methodology BSAC Disc Diffusion Template programme BSAC Standardized Method Development Centre

9 BSAC Standardized Disc Susceptibility Testing Method Current version Current version 3 January 2004 Changes included in the most current version of the method Previous versions Version November 2003 Version May 2003 Version February 2003 Version August 2002 Version January 2002 Version 2.1 August 2001 Version 2 July 2001 Additional Methodology Detection of Extended Spectrum Beta-lactamases (ESBLs) in E. coli and Klebsiella spp. The use of Etests with BSAC Methodology MIC testing of M. catarrhalis with ampicillin/amoxycillin Testing for dissociated resistance in Staphylococci

10 Presentation of MIC breakpoints (mg/L) (Major organisational change) In line with European consensus (EUCAST) MIC  (as previously) MIC breakpoint concentration = organism susceptible MIC > (previously  ) MIC breakpoint concentration = organism resistant Appearance in the tables Previously R  16, S  8 Changes to R > 8, S  8 Avoids the theoretical `gap’ inherent in the previous system

11 MIC and zone breakpoints for Enterobacteriaceae and Acinetobacter g. Salmonella spp. – for ciprofloxacin there is clinical evidence to indicate a poor response in systemic infections caused by Salmonella spp. with reduced susceptibility to fluoroquinolones (ciprofloxacin MICs mg/L). This reduced susceptibility is most reliably detected with nalidixic acid 30  g discs as strains with reduced susceptibility show no zone of inhibition.

12 N. gonorrhoeae Resistance to ceftriaxone, cefotaxime and cefixime has not been described, however isolates with chromosomally encoded reduced susceptibility to penicillin have slightly reduced zones of inhibition with these antibiotics but remain susceptible. Results for isolates with reduced zones around ceftriaxone, cefotaxime and cefixime discs should be confirmed by MIC determinations. NB. Referral to the Reference Laboratory at Colindale Only send isolates with reduced susceptibility to azithromycin or the cephalosporins

13 Detection of ESBLs in E. coli and Klebsiella species As a general rule laboratories should test isolates to both ceftazidime (best indicator for TEM and SHV-derived ESBLs) and cefotaxime (the best indicator for CTX-M types) Alternatively, cefpodoxime can be used as an indicator for all ESBLs Any organism showing reduced susceptibility to ceftazidime, cefotaxime or cefpodoxime should be investigated for ESBL production Many different methods but all depend on detecting synergy between clavulanic acid and the indicator antibiotic/s used in primary screening

14 S. maltophilia:All isolates with co-amoxyclav MICs of 32 mg/L Data provided by Anna King

15 Stenotrophomonas maltophilia Difficult to test because results are affected by temperature of incubation and media content. All aminoglycosides, polymixins and carbapenems should be reported resistant without testing Most, but not all, S. maltophilia are susceptible to cotrimoxazole. Testing should be at 30 0 C zone of  20 mm = S. For  -lactams and quinolones susceptibility testing is unreliable, but combinations of ciprofloxacin and a  -lactam or aztreonam and co-amoxyclav have had a favourable clinical response.

16 Testing for dissociated resistance in staphylococci Organisms exhibiting blunting Isolate has MLS B and clindamycin should be used with caution (if at all). NB. Disc on the left 5  g erythromycin, disc on right 2  g clindamycin

17 Under review Alpha-haemolytic streptococci Coryneforms Fast growing anaerobes


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