Transcript Recent Changes to the Recommendations
Recent Changes to the Recommendations
Jenny Andrews
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 Medical Professor MacGowan (President of the BSAC) Professor C. Gemmell Dr. N. Damani Dr. M. Dryden Dr. N. Brown Dr. G. Kahlmeter (SRGA & EUCAST) Veterinary Service Mr. C. Teale Industry Mr. P. Wheat (Mast) Mr. C. Booth (Oxoid)
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 Version 2 July 2001 2.1 2.1.1 2.1.2 2.1.3 August 2001 January 2002 August 2002 February 2003 2.1.4
2.1.5
3 May 2003 November 2003 January 2004 (current version)
BSAC website (www.bsac.org.uk)
Site Directory What’s on News Resources Guides External Contacts Discussions Grants & Awards Journal About BSAC ANNOUNCEMENTS BSAC Working Party Publications Consumer Section Evidence Based Medicine & Clinical Effectiveness Garrod Medal & Lecture JAC Misc National Prevalence Survey of MRSA Therapy Past Events Publications Resistance Surveillance Susceptibility Testing Alliance for the Prudent Use of Antibiotics Awards Consultations Education Resource External Contacts Grants Programme Membership MRSA Newsletter Powerpoint Presentations PUBMED SARS What’s On
BSAC website (www.bsac.org.uk)
Site directory What’s on News Resources Guides About BSAC Announcements BSAC Working Party Publications Education Resource Garrod Medal & Lecture Alliance for prudent use of Antibiotics Awards Consumer-section Evidence Based Medicine & Clinical Effectiveness Grants Programme External Contacts Discussions JAC MISC Membership Grants & Awards Journal Newsletter PowerPoint Presentations PUBMED SARS What’s on National Prevalence Survey of MRSA Therapy Past events Publications Resistance Surveillance Susceptibility Testing
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
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
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
BSAC Standardized Disc Susceptibility Testing
Current version Current version 3 January 2004
Method
Changes included in the most current version of the method Previous versions Version 2.1.5 November 2003 Version 2.1.4 May 2003 Version 2.1.3 February 2003 Version 2.2.2 August 2002 Version 2.1.1 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
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
Changes to R > 8, S
8 8 Avoids the theoretical `gap’ inherent in the previous system
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 0.125-1 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.
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
Detection of ESBLs in
E. coli Klebsiella
species and
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
S. maltophilia:All isolates with co-amoxyclav MICs of 32 mg/L
Data provided by Anna King
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.
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