Modifications

Additions and modifications in this edition of the manual.

The following additions and modifications have been made to the online edition of the manual (including downloadable pdf versions) since the inception of the online edition in September 2006. Minor formatting and phrasing changes are not listed. Note that this section is cumulative and all changes that have been made in the recent past can be found here or by using the site’s search engine.

October 2016

Launch of the on-line and printed versions of the 8th Edition of the CDS Manual. There has been numerous minor additions, modifications, deletions and corrections and these will not be listed here, but the major changes are listed below:

Disc testing of Nocardia sp.: This was reviewed and found to lack robustness in the field and no longer is included in the CDS test.  Quantitative methods are the appropriate techniques for testing this species.

Disc testing of yeasts: Antimicrobial testing of yeast has been deleted from the CDS due to a lack of mycology expertise to support the method and the availability of more appropriate techniques.

Quality Assurance: A number of items relevant to enhancement of quality assurance and compliance with regulatory requirements for the use of in-house IVDs have been included in the 8th Edition of the CDS Manual. These include the revision and restocking of Reference Strains used in the CDS Test. ACM strains are no longer available and the alternatives are listed in Table 3.1 of the Manual. In addition NATA’s recommendations on the maintenance of Reference Strains is included as Appendix 3. In March 2016 TGA revised its regulatory requirements for in-house IVD’s and a copy of this document is included in the Manual as Appendix 2.

Neisseria Susceptibility Testing: Prof. Monica Lahra has updated and enhanced the section on antimicrobial susceptibility testing on Neisseria sp.. This will serve as a useful reference source for diagnostic laboratories but the routine diagnostic laboratory’s role and responsibility in managing these important public health disease are defined in the 8th edition in section 6.1. The  details of more extensive laboratory testing of these species by the reference laboratory are set out in Section 6.2.


December 2013

Compliance with in-house in vitro diagnostic device requirements: Detailed information is given in the 7th edition of the manual to ensure that the CDS will comply with the statutory requirements for the use of in house in vitro diagnostic devices that are proposed for introduction by TGA in 2014.


August 2013

Disc Testing of Nocardia sp: The method of disc testing Nocardia sp. is under review (see Newsletter 32).
Susceptible breakpoint for cefazolin: The susceptible breakpoint of cefazolin and Gram negatives has been corrected to 4mg/L in Table 10.1.b.  Due to a clerical error previously it was recorded as 16 mg/L.
Calibration of ceftaroline for testing MRSA (See Newsletter 33)Ceftaroline has been calibrated for MRSA and the results are shown in Table 10.1.and the results for the reference strain of Staph. aureus ACM 5190 are included in Table 10.3.


December 2012

Calibration of doxycycline and enterococci: Tables 10.1.a “Calibrations” has been modified to include doxycyline in the section headed Enterococci.  Table 10.3.a  “Reference strains” also has been changed to include doxycycline in the sectioned headed Enterococcus faecalis.  See Newsletter 31.


September 2012

Changes to Neisseria gonorrhoeae Testing: A/Prof. Monica Lahra has updated the section on testing Neisseria gonorrhoeae. Major changes have been made to the description at 5.8.2 including the list of references at the end of chapter 5, Table 10.1.b (Neisseria gonorrhoeae),and Table10.3.b (Neisseria gonorrhoeae). Note also a change in footnote a  in reference to (Neisseria gonorrhoeae) in this table.


April 2012

1. Calibration of Fosfomycin This antibiotic has been calibrated for the CDS for use in uncomplicated urinary tract infections using a Fosfomycin/Trometamol 200µg disc (Oxoid, FOT 200, CT0758). It is emphasised that this antibiotic has not been calibrated for systemic use and it is best regarded as a urinary antiseptic. Enterobacteriaceae and Pseudomonas sp. are tested on Sensitest agar and enterococci are tested on blood Sensitest agar.
Enterobacteriaceae, Pseudomonas species
MIC of susceptible strains                            ≤ 32 mg/L
Annular radius of susceptible strains          ≥ 6 mm
Enterococcus species (tested on Blood Sensitest agar, 35oC, 5 % CO2)
MIC of susceptible strains                            ≤ 64 mg/L
Annular radius of susceptible strains          ≥ 6 mm
Note: With this antibiotic in vitro mutation to resistance is high with the majority of strains tested and this is demonstrated by the presence of resistant colonies within the inhibitory zones on disc testing. However, it is claimed that the reason for the clinical efficacy is that a fosfomycin urine level of > 128 mg/L is maintained for over 24h after a single 3g oral dose (Raz, R, Fosfomycin: an old—new antibiotic, Clinical Microbiology and Infection, vol. 18, 4–7, 2012). Acinetobater species are considered inherently resistant to fosfomycin. With Enterobacteriaceae and Pseudomonas sp., when there is a double zone of confluent growth, the measurement of the annular radius is performed on the inner zone.
Acceptable range for quality control (annular radius in mm)
Escherichia coli ACM 5185:                                         5.7    –     9.7
Pseudomonas aeruginosa ACM 5189:                           8.0   –    10.8Enterococcus faecalis ACM 5184:                                7.1    –    10.7

 2.    Modified susceptible breakpoint MIC for Augmentin® (2 parts of amoxicillin to one part of clavulanate).

The susceptible breakpoint MIC of Augmentin® has been changed to 8/4 mg/L (8 mg/L amoxicillin and 4 mg/L clavulanate) for Acinetobacter and Enterobacteriaceae and Vibrionaceae. The cut off annular radius of susceptible strains remains the same at 6 mm with an Augmentin 60 µg disc. In the quality control of AMC 60 discs, the acceptable range for the reference strain Escherichia coli ACM 5186 is unchanged i.e. 6.4 – 9.6 mm.

Note: the susceptible breakpoint MIC of Augmentin® is unchanged at 8/4 mg/L for Burkholderia species.

3.    Modified susceptible breakpoint MIC for Timentin® (ticarcillin in the presence of a fixed level of 2mg/L clavulanate)

The new susceptible breakpoint MIC of Timentin® is 16/2 mg/L. The cut off annular radius of susceptible strains with a Timentin® 85 µg disc is unaltered at 6 mm. The reference strain E. coli ACM 5186 is also used in the quality control of Timentin® 85 discs and its acceptable range with a Timentin® 85 disc is unchanged i.e. 6.0 – 8.4 mm.

4.    Timentin® (ticarcillin in the presence of a fixed level of 2mg/L clavulanate) is no longer recommended testing for anaerobic organisms and is removed from Table 10.1.c.

5.    Ticarcillin testing for Pseudomonas species is removed from Table 10.1.b.

6.    Testing Staphylococcus species that do not grow on Sensitest agar

Rare isolates of Staphylococcus species will failing to grow on Sensitest agar are tested on blood Sensitest agar (in air or 5 % CO2). Interpretation of results is the same as those of staphylococci tested on Sensitest agar.


March 2012

1.EnterococciTetracycline has been added to Table 10.1.a Enterococci. The disc potency is 10 µg, the breakpoint MIC for susceptible strains is < 4 mg/L and the zone size of susceptible strains is > 6 mm. Table 10.3.a has been modified also to show the results of QA testing with Enterococcus faecalis ACM 5184 . The acceptable range with a 10 µg disc is 7.0 – 10.2 mm.


September 2011

1.  Citrobacter amalonaticus addedCitrobacter amalonaticus is a Citrobacter species biochemically indistinguishable from Citrobacter koseri but it produces a class A inducible β-lactamase. See section 5.7.iii and Table 4 for details and information about testing and reporting β-lactam antibiotics.

2.  Changes in Testing Neisseria gonorrhoeae

Additional Neisseria gonorrhoeae reference strains:

Neisseria gonorrhoeae WHO K and Neisseria gonorrhoeae WHO P

Azithromycin 15 µg disc calibrated for the testing of Neisseria gonorrhoeae (section

3.  Addition of new Plates

Plate 13.10.A:  Klebsiella pneumoniae with the recommended positioning of β-lactam discs providing the detection of ESBL, inducible AmpC or inducible class A β-lactamases in routine testing.

Plates 11.15.A and 11.15.B: MBL and ESBL producing K.  pneumoniae in CDS routine testing and confirmation.

Plates 11.15.C and 11.15.D:  Klebsiella pneumoniae  carbapenemase (KPC) producing K.  pneumoniae in CDS routine testing and confirmation.


August 2011

  1. Revised Interpretation of Testing Streptococci and cefotaxime/ceftriaxone : The interpretation of the results of testing of Streptococcus pneumoniae from sites other than CSF and other streptococci including strains of the Streptococcus milleri group (S. anginosus, S. constellatus, S. intermedius) against cefotaxime/ceftriaxone 0.5 µg discs has been revised. The cut off zone size is 4 mm annular radius and the susceptible breakpoint is ≤ 0.5 mg/L.
  1. Decreased Susceptibility (DS) Report: Although an Intermediate category of susceptibility is generally not accepted in the CDS Test there are a few occasions where it is useful to distinguish between those isolates that are not fully susceptible to a particular agent.  Previously we referred to these isolates as having a Reduced Susceptibility (RS) but as some found this term confusing we have adopted the term Decreased Susceptibility (DS) that is used in reporting ceftriaxone susceptibility for Neisseria gonorrhoeae.
  1. Surrogate Testing of Augmentin: As requested by some members of the CDS Users Group, the surrogate reporting of Augmentin for Streptococcus pneumoniae from sites other than CSF will be included in Table 10.2.a.
  1. Amendment to Table 10.4.: With Serratia marcescens read T (tested) for Tazocin instead of R; Aeromonas sobria will be replaced by A. sobria/veronii and with Proteus vulgaris/penneri, aztreonam should be tested (T) and the susceptibility reported.
  1. Use of an ampicillin and a cephalexin disc: We recommend to test in parallel ampicillin 25 µg and cephalexin 100 µg Acinetobacter species and members of the Enterobacteriaceae.  Organisms producing chromosomal AmpC β-lactamase are obviously resistant to cephalexin 100 µg but may yield a zone around 6 mm with ampicillin. These strains should be reported as resistant to ampicillin.
  1. Detection of Decreased Susceptibility to fluoroquinolones: We recommend the testing of all coliforms isolated from blood culture including Salmonella sp. and E. coli with nalidixic acid 30 µg as well as ciprofloxacin 2.5 µg to detect a decreased susceptibility to the fluoroquinolone of the isolates.
  2. Testing Salmonella sp. against azithromycin: Salmonella typhi and other Salmonella species isolated from blood culture have been calibrated in the CDS using an azithromycin 15 µg disc. The Australian Antibiotic Guidelines recommend azithromycin as the treatment of choice for Salmonella typhi.  Although it is surprisingly high we have tentatively accepted a susceptible breakpoint of 16 mg/L as this is based on clinical outcome and in vitro testing reported in the literature (Buttler et al., 1999, JAC, 44, 243-250; Capoor et al., JMM 2007, 57, 1490-1494). The cut off of the annular radius for susceptible strains is 4 mm. The acceptable range obtained with E. coli ACM 5185 is 5.4 – 7.0 mm.
  1. Unusual MRSA isolate: We recently came across an MRSA isolate with a FOX 10 zone of approximately 6mm. The strain was mecA gene positive by PCR testing.  CDS Users are reminded that mecA gene negative strains i.e. MSSA always have a zone of ≥ 7 mm. Therefore, a coagulase positive staphylococcus with a FOX 10 zone of less than 7 mm may belong to this group of low resistance MRSA. Please forward the isolate to us for PCR confirmation. In the meantime, you can either withhold the results or send the results out as “probable MRSA awaiting PCR confirmation”.
  1. Klebsiella pneumoniae carbapenemase (KPCs): Although KPC producing K. pneumoniae have been reported over the last few years in Europe and USA, the first strain isolated in Australia was reported in September 2010. KPCs are essentially “super” ESBLs of Bush group 2 (Ambler class A) plasmid mediated β‑lactamases and hydrolyse all β-lactam antibiotics including the carbapenems. Although inhibited by clavulanic acid and sulbactam, the enzyme is very efficient and affects all β-lactams including Timentin, Augmentin and Tazocin, see Power points 2011.
  1. High level aminoglycoside resistance in E. faecalis: All enterococci are known to be resistant to the aminoglycosides and all isolates would have a zone < 6mm with a gentamicin 10 ug disc (CN 10). Therefore enterococci are not calibrated against CN 10.  However CN 200 and S 300 discs have been calibrated in the CDS to detect high level resistance to these aminoglycosides in isolates of E. faecalis from blood cultures in patients with suspected endocarditis caused. If the isolate does not have high level resistance, gentamicin or streptomycin may used to provide synergy to ampicillin.  Note that the high level resistance is mediated by a different mechanism in each of the two aminoglycosides therefore if needs be both should be tested.
  2. Apramycin zone: Please note that the 4 mm cut off in annular radius of aminoglycosides with the Gram-negative isolates applies to all aminoglycosides including apramycin that is used in veterinary medicine.
  3. Confirmation of MBLs using EDTA discs: When using EDTA discs to perform MBL confirmatory testing it is necessary to include an aztreonam 30 µg disc (ATM 30). As aztreonam is not affected by MBL an MBL producer will be susceptible to ATM 30 unless it also expresses an ESBL. The co-presence of an MBL and an ESBL can be clearly demonstrated in members of the Enterobacteriaceae by the resistance to ATM 30 and the synergy observed between ATM 30 and an adjacent ACM 60 disc, see power points 2011.With Pseudomonas aeruginosa, some isolates may show a non-specific synergy between EDTA and a beta-lactam disc including ATM 30 that does not indicate the presence of an MBL (see power points 2009).

December 2010

1. Quality control3.1.4. Measuring and recording reference strains results
When testing an antibiotic against the reference strains if the annular radii lie outside the acceptable interval on two consecutive testings, retest using a new cartridge from the same batch. If the annular radii from the new cartridge also lie outside the acceptable interval, discontinue the use of this batch. The reason being that with 95% confidence limits, there is a chance of the reading to “occasionally” land outside the acceptable range but is unlikely on two consecutive testings.

2.Change in wording of report of Streptococcus pneumoniae susceptibility

Streptococcus pneumoniae isolated from sites other than CSF, that have a zone with P 0.5 u or CTX/CRO 0.5 µg of < 6mm in annular radius and a zone with  AMP 5 or CTX/CRO 5 µg of > 6 mm are now reported as having a “Decreased Susceptibility” (DS) instead of “Reduced Susceptibility” (RS).

3.    Use of 2 disc potencies for Streptococcus sp.

The testing with P 0.5 u or CTX/CRO 0.5 µg disc and AMP 5 µg or CTX/CRO 5 µg disc is to be used for all Streptococcus species including S. milleri.   Interpretation and reporting the results are the same as with S. pneumoniae.

4.    Reporting of Plasmid Mediated AmpC (PM-AmpC)

The results of susceptibility testing are reported according to the standard. CDS interpretation.

5.    Reporting of Klebsiella oxytoca

The results of susceptibility testing of K. oxytoca hyperproducer of K1 enzyme are reported according to the standard CDS interpretation.

6.    Further studies on the ESCHAPM Group.

EEC group to replace ESCHAPM Group (sections 5.2 and 5.5.7).

7.    Table 10.4.

Table 10.4 a guide to the reporting of β-lactam antibiotics has been simplified.


August 2010

2.3. Interpretation of resultsExceptions to the Standard Interpretation:

Exceptions to the standard 6 mm annular radius cut off are flagged in Table 10.1 Calibrations.

The Table of Exception was removed.

Table 3.1 Reference Strains.

Added Reference Strain:

Accession No.

Reference Strain


WHO K Neisseria gonorrhoeae 

3.1.1. Obtaining reference strains

Deleted the ACM reference as the Australian Collection of Micro-organisms (ACM) has suspended its activity for the time being.

3.3. External quality assurance program

5.  If requested to test an organism not calibrated for the testing by the CDS, we can extend the testing from an organism with similar growth requirement and behaviour. For example, the testing and reporting of Chromobacterium sp. may be extended from that of non-fastidious Gram negative bacillin such as Pseudomonas sp.

5.5.9 Salmonella species and Escherichia coli with decreased susceptibility to ciprofloxacin

Treatment failure has been reported with invasive Salmonella infections and E. coli septicaemia where….. . Salmonella sp. and blood culture E. coli isolates should be …

gene gyrA in Salmonella species and E. coli confer …..Report as resistant to ciprofloxacin.

5.8.2. Neisseria gonorrhoea

Ceftriaxone

Resistance to ceftriaxone, i.e., properly documented treatment failure with ceftriaxone, given as a single 500 mg intramuscular dose, has not yet been recorded. “The susceptibility of Neisseria gonorrhoeae to the extended spectrum cephalosporins (ESCs), which include ceftriaxone, the current first line of treatment for gonorrhoea, has been decreasing worldwide. To assist in the laboratory detection of gonococci with decreased susceptibility (DS) to Ceftriaxone, using the Ceftriaxone 0.5ug disc, the Cefpodoxime CPD10ug disc has recently been included to assist in the detection of gonococci with decreased susceptibility to Ceftriaxone. Thus a WHO control panel strain namely ‘Neisseria gonorrhoeae WHO K’  is listed which displays decreased susceptibility to Ceftriaxone due to the presence of a penA mosaic allele, an alteration in the penicillin binding protein2 (PBP2).

Categories of susceptibility are defined as follows:

·        Susceptible to ceftriaxone.

The annular radius of the inhibitory zone around a ceftriaxone 0.5 μg disc is > 9 mm and > 12 mm around a cefpodoxime 10 μg disc.

·        Decreased susceptibility to ceftriaxone.

The annular radius of the inhibitory zone is between 5 mm and 9 mm around a ceftriaxone 0.5 μg disc and between 7 mm and 12 mm around a cefpodoxime 10 µg disc. This result should be confirmed by determining the MIC of ceftriaxone. 

8. Application to veterinary medicine

8.2. Erythromycin and Pasteurella sp.

As requested by Veterinary Laboratories, erythromycin has been calibrated on Blood Sensitest Agar at 35oC in 5% CO2 atmosphere for the testing of Pasteurella sp. isolated from respiratory infection specimens of dogs and cats.

Annular radius of susceptible strains          ≥ 4 mm

Susceptible MIC                                        ≤ 2 mg/L


September 2009

-Ciprofloxacin 2.5 μg can used as a surrogate disc for reporting the susceptibility to Ofloxacin as listed in tables 10.2.a and 10.2.b.
-Insertion of the protocol for the recover of lyophilised quality assurance strains.
-Due to a renewed interest in the global surveillance of Neisseria gonorrhoeae antimicrobial resistance, a panel of eight additional strains of Neisseria gonorrhoeae (WHO F, G and K to P) are now included in the CDS quality control reference organisms. See section 3.1 of the CDS manual for details.


August 2009

The Neisseria Reference Laboratory recommends incubating Neisseria gonorrhoeae cultures at 35 to 36°C and that stock cultures be maintained on paraffin covered chocolate agar slopes at 30 to 36° C.


July 2009

Neisseria gonorrhoeae strains with a Ceftriaxone MIC between 0.03 and 0.25 are now categorised as non-susceptible rather than less susceptible as the clinical significance is currently uncertain.
-Quality assurance ranges for Clarithromycin against Staphylococcus aureus ACM 5190 inserted into Table 10.3.a
-The Neisseria gonorrhoeae specified Annular Radius to Nalidixic Acid (30 µg) for Susceptibility to Ciprofloxacin has changed from  ≥ 6 to > 6 and for Ciprofloxacin (1 µg) from ≥ 6 to > 6.
-The specified Annular Radius to Nalidixic Acid (30 µg) for Resistance to Ciprofloxacin has changed from < 6 to 0.  The Annular radius to Ciprofloxacin remains unchanged. See Table 10.1.b
-The Neisseria gonorrhoeae MIC for Susceptibility to Ceftriaxone has changed from ≤ 0.03 to < 0.03 and the Annular Radius from > 8 to > 9. The MIC for Less Susceptible has changed from 0.06 – 0.25 to 0.03 – 0.25 and the Annular Radius from 5 – 7 to 5 – 9. See Table 10.1.b

-The Neisseria gonorrhoeae Annular Radius for Less Susceptibility to Benzylpenicillin has changed from 4 – 9 to 3 – 9 mm. The Annular Radius for Resistance has changed from ≤ 3 to < 3 mm. The MICs remain unchanged. See Table 10.1.b (Table 5a of the Fourth Edition).

-A new section has been inserted between sections 4.5.1 and the previous 4.5.2 covering Borderline Oxacillin Resistant Staphylococcus Aureus (BORSA). The existing sections 4.5.2 to 4.5.9 are consequently renumbered 4.5.3 to 4.5.10.

-Pristinamycin has been removed from Tables 10.1.a and 10.3.a. It is now recommended that susceptibility to Pristinamycin be based on the surrogate antibiotic Quinupristin/Dalfopristin (Table 10.2.a).

-A new section has been inserted between 5.5.1 and the previous 5.5.2 covering Inhibitor Resistant TEM (IRT). The existing sections 5.5.2 to 5.5.6 are consequently renumbered 5.5.3 to 5.5.7

-A new section has been inserted between 5.5.5 and the previous 5.5.6 for Yersinia enterocolitica. The existing sections 5.5.6 and 5.5.7 are consequently renumbered as 5.5.7 to 5.5.8

-Section 5.11 has been relocated and is now section 5.5.9

-The Appendix 1 “β Lactamases in Gram negative organisms” has been removed from the manual. Information relevant to the performance of the CDS test has been relocated into chapter 5.

-All coagulase negative staphylococci with heterogeneous resistance to methicillin will have annular radius of < 6 mm to Oxacillin 1 µg. Consequently, Section 4.5.7, subheading ‘Heterogenous methicillin-resistance in CNS’ and the following paragraph have been removed from the manual.

-A new section has been inserted between sections 4.4 and the previous 4.5 covering susceptibility testing of Nocardia. The existing sections 4.5 to 4.7 are consequently renumbered 4.6 to 4.8
-Neomycin has now been added to list of exceptions to the standard interpretation. The susceptibility boundary for Staphylococci, Acinetobacters, the Enterobacteriaceae and the Vibrionaceae with Neomycin 30 μg is now 4 mm and the MIC ≤8.

-All yeast susceptibility testing is now performed on Casitone complex media. Yeast Nitrogen Base has been discontinued as a CDS medium.

Candida parapsilosis ACM 5283 has replaced Candia albicans as the quality control reference organism for yeast susceptibility testing. Table 10.3.d shows the new quality control reference strain ranges for this organism.


December 2008

-The veterinary antibiotic Cefovecin has been assessed and determination of susceptibility is based upon surrogate disc testing as defined in tables 10.2.a and 10.2.b.
-Marbofloxacin discs have been calibrated for the susceptibility testing of veterinary isolates. Tables 10.1.a, 10.1.b 10.3.a and 10.3.b


October 2008

95% confidence intervals for the reference strain Pseudomonas aeruginosa against Norfloxacin 10 μg added to table 10.3.b.


June 2008

The protocol for the handling and storage of reference strains extended to cover Neisseria gonorrhoeae.


May 2008

We now recommend that Proteus vulgaris or Proteus penneri, which possess a Bush group 2e β‑lactamase, be reported as resistant to both Cefpirome and Cefepime

We now recommend that Klebsiella oxytoca K1 hyperproducers be reported as resistant to both Cefpirome (CPO) and Cefepime (FEP).Augmentin (AMC), Timentin (TIM) and Tazocin (TZP) should only be tested against urinary isolates of this organism; from all other sites report it as resistant to these antibiotics.
Caspofungin and Posaconazole calibrations have been added to Table 10.1.d Yeast.
Following recalibration, we now recommend using Tetracycline 10 μg for all susceptibility and quality assurance testing. The quality assurance 95% confidence intervals for the 10 μg discs are listed in the calibrations table in this edition of the CDS manual.


February 2008

β‑lactamases of Stenotrophomonas maltophilia now mentioned in section 5.11


June 2007

Inserted into Table 10.2.b (Surrogate disc testing): Ciprofloxacin 2.5 μg can used as a surrogate disc for reporting the susceptibility of Pseudomonas to norfloxacin.
Inserted Enterobacteriaceae calibrations for Polymyxin B into 10.1.b
Inserted the acceptable range for Polymyxin B when tested against reference strain Escherichia coli ACM 5185 into Table 10.3.b.


May 2007

Streptomycin calibrations have been added to Tables 10.1.a and 10.3.a for enterococci.
Recalibration of gentamicin for enterococci (Table 10.1.a)
Cotrimoxazole calibrations have been added to Tables 10.1.a for Listeria.
Voriconazole calibrations have been added to table 10.1.d Yeast.


March 2007

The protocol for detecting and confirming metallo‑β‑lactamase (MBL) expression has been modified and extended to assist in detecting co-expression of an MBL and an ESBL (Sections 5.1, 5.5.6 and 5.10 in this edition of CDS manual).
Wire manufacturers have now switched from SWG (Standard Wire Gauge) gauges to B&S (Brown and Sharp) gauges. Accordingly, it was necessary to switch from the previously specified 0.56 mm SWG (SWG 24) gauge to 0.574 mm B&S gauge (B&S 23 nichrome wire). This has been evaluated and no significant difference in inoculum strength or zone size was detected. Note: Don’t confuse SWG with AWG – AWG (American Wire Gauge) is equivalent to B&S.
The previously listed nichrome wire supplier has closed down. New suppliers are now listed in Section 2.1 of this manual.
We now recommend that Moxifloxacin (and not Ciprofloxacin) be used as the surrogate for Enrofloxacin and Orbifloxacin (See Newsletter 21)


February 2007

Tigecycline calibrations have been added to Tables 10.1.a and 10.1.b


December 2006

References are now included at the end of each chapter.


November 2006

Some sections of the manual have been rewritten for improved clarity, without changing the actual information content.
Section 3.1.2. on the ‘Handling and storage of reference strains’ has been expanded to clarify the preferred method of storage and recovery of reference organisms as well an acceptable alternative where -70°C storage is not available.
Tables formatted for consistency of formatting between web site and printed edition.
Table 5a (Neisseria gonorrhoeae calibrations) is now incorporated into Table 10.1.b (Gram-negative calibrations)
Table 5b (Neisseria gonorrhoeae reference strain quality control) is now incorporated into Table 10.3.a (Gram-negative reference strain quality control)
Table 6a (Anaerobe calibrations) is now incorporated into Table 10.1 as Table 10.1.c.
Table 6b (Anaerobe reference strain quality control) is now incorporated into Table 10.3 as Table 10.3.c.
Table 7a (Yeast calibrations) is now incorporated into Table 10.1 as Table 10.1.d.
Table 7b (Anaerobe reference strain quality control) is now incorporated into Table 10.3 as Table 10.3.d.
Tables, Figures and Plates are now numbered within in each chapter and preceded by the chapter number.
Photographic plates have been rearranged to make it easier to find examples relating to particular organisms.