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
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)
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
August 2001
2.1.1
January 2002
2.1.2
August 2002
2.1.3
February 2003
2.1.4
May 2003
2.1.5
November 2003
3
January 2004 (current version)
BSAC website (www.bsac.org.uk)
Site Directory
About BSAC
Alliance for the Prudent
Use of Antibiotics
What’s on
ANNOUNCEMENTS
Awards
News
BSAC Working Party
Publications
Consultations
Resources
Consumer Section
Education Resource
Guides
Evidence Based Medicine &
Clinical Effectiveness
External Contacts
External Contacts
Garrod Medal & Lecture
Grants Programme
Discussions
JAC
Membership
Grants & Awards
Misc
MRSA
Journal
National Prevalence Survey
of MRSA Therapy
Newsletter
Past Events
Powerpoint
Presentations
Publications
PUBMED
Resistance Surveillance
SARS
Susceptibility Testing
What’s On
BSAC website (www.bsac.org.uk)
Site directory
About BSAC
Alliance for prudent use
of Antibiotics
What’s on
Announcements
Awards
News
BSAC Working Party
Publications
Consumer-section
Resources
Education Resource
Evidence Based Medicine
& Clinical Effectiveness
Guides
Garrod Medal & Lecture
Grants Programme
External
Contacts
JAC
Membership
Discussions
MISC
National Prevalence
Survey of MRSA Therapy
Grants & Awards
Newsletter
Past events
Journal
PowerPoint Presentations
Publications
PUBMED
Resistance Surveillance
SARS
What’s on
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
Method
Current version
Current version 3 January 2004
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  8
Changes to R > 8, S  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 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
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 300C 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 MLSB
and clindamycin
should be used
with caution (if at
all).
NB.
Disc on the left 5
g erythromycin,
disc on right 2 g
clindamycin
Under review
Alpha-haemolytic streptococci
Coryneforms
Fast growing anaerobes