Amsterdam 2005 I C G -- International Collaboration on Gonococci

International Collaboration on Gonococci (ICG) Workshop

in conjunction with the 16th Biennial meeting of the International Society for Sexually Transmitted Diseases Research (ISSTDR)

Amsterdam, The Netherlands

July 10, 2005


Approximately 25-30 people attended the workshop.

Workshop record

Dr Magnus Unemo ( from the Swedish Reference Laboratory for Pathogenic Neisseria, Örebro University Hospital, Sweden and Dr John Tapsall ( from the WHO Collaborating Centre for STD and HIV, Sydney, Australia kept record for the workshop.

Introduction to ICG

Dr John Tapsall reviewed the origin, background and aims of ICG and the previous ICG meetings. The ICG arose from initial discussions between WHO and CDC in May 2000 with a view to enhancing production of and access to global data on gonococcal antimicrobial resistance (GC AR). Since the preliminary meeting at the 12th International Pathogenic Neisseria Conference (IPNC) in Galveston, USA (November 2000), annual meetings have been convened. It is acknowledged however that most ICG members are unable to attend these meetings so that electronic communication has been a main aim for keeping contact. At the second meeting (ISSTDR/IUSTI Meeting, Berlin, Germany in June 2001), the ICG was formed together with five Working Groups to consider and make recommendations on specific issues relevant to GC AR surveillance or other biological/laboratory aspects important for control of the spread of gonococcal disease. The Working Groups were named as follows: Diagnostics including molecular diagnostics, Gonococcal typing, Laboratory quality systems, Sampling and methodology, and Resistance mechanisms and ICG website development.

The aims of the ICG are:

Membership to the ICG is free and open to anyone working or interested in the broad areas of epidemiology, microbiology, and management of gonococcal disease. Members are encouraged to join and contribute to one or several of the existing Working groups. In addition, suggestions for the formation of additional groups are always welcome.

Dr Tapsall presented the previous outcomes of the ICG Working Groups. Briefly, a study of different molecular GC typing methods, comparisons of methods used for antimicrobial susceptibility testing, and an evaluation of methods for molecular GC diagnostics have been performed. In addition, a new panel of quality assurance/quality control (QA/QC) strains for antimicrobial susceptibility testing has been evaluated and several sampling approaches have thoroughly been reviewed and discussed.

Progress Reports from the ICG Working Groups

I) Resistance mechanisms and ICG website development

ICG website (

A summary update was provided by Dr Jo-Anne Dillon. Progress on the website had been delayed because of the limited amount of time available to devote to it, but Dr Liao hopes to make progress shortly. The members of ICG were requested to provide ideas and suggestions concerning what to include on the website.

For example, methodology that can be of interest, validated raw data or aggregated data, links to other websites that may be of interest, and recent articles to be highlighted. Dr ML Liao will be responsible for the practical work of constructing and updating the website.

Molecular mechanisms for assessment of antimicrobial resistance in GC

Dr David Trees briefly reviewed the presently known molecular mechanisms of resistance to the different antimicrobials that are of interest for treatment of GC disease. In addition, Dr Trees described many different molecular techniques that are utilised for identification of decreased susceptibility or resistance to the antimicrobials e.g. probe hybridization, PCR, conventional sequencing, microarray, transformation, Tm analysis (with or without sequence confirmation), and pyrosequencing. The members of ICG attending agreed with the opinion of David Trees regarding the use of the molecular methods for AMR for GC. At present these are only applicable for presumptive identification of resistance in GC strains or in GC positive nucleic acid amplification test (NAAT) specimens. Furthermore, the methods can mainly identify previously known mechanisms for resistance and not any new emerging resistance. The methods may be used as surveillance/screening tools to predict relative prevalence of resistance. However, this is only for an initial screening that gives presumptive prevalences, and for definitive results, a culture-based program with subsequent conventional antimicrobial susceptibility testing should be retained.

II) Sampling and methodology

Sampling requirements for GC AR surveillance

Dr Tapsall described the need for a sample that is representative and with sufficient statistical power to identify the 5% prevalence of resistance threshold at which gonorrhoea treatment recommendations are changed. In practice, 100-200 GC isolates can be routinely obtained and examined. However, if a resistance rate of approximately 3-8% is detected, an enhanced surveillance is needed before conclusions of changed gonorrhoea treatment recommendations.

These recommendations are based on the assumption that the critical threshold for resistance prevalence is indeed 5%.

Subsequent to the meeting, a publication (Roy K, et al, EID 2005;11:1265-1273) has appeared and would be of interest to members interested in this area. Dr Susan Wang, an active member of the ICG, is a co-author.

Use of First Void Urine (FVU) samples positive in PCR for GC to increase sample size for GC AR monitoring

NAATs are increasingly replacing culture of GC for routine diagnostics. However, GC isolates are still needed for AR testing. Due to these facts, Dr Tapsall and colleagues have performed a study to examine the viability of GC in FVU samples positive in GC PCR. The viability varied for different GC strains and extremes of the pH and the osmolarity of the FVU affected the yield. However, FVU from males were considered as "reasonable" to maintain viability of GC, e.g. GC were grown from 74% of the FVU inoculated within 24-48 h after collection.

(available on See Abstract WP - 010 page 270 of ISSTDR meeting abstracts - there are many interesting abstracts by ICG members available)

III) Laboratory quality systems

Current status of international panel of GC QA/QC strains for antimicrobial susceptibility testing

An update was provided by Dr Tapsall for Dr Joan Knapp who was unable to attend. Previously, an international panel consisting of five GC strains (WHO A-E) has been used in several countries, but these were not representative of current resistance patterns. An ICG project was conducted by Dr Knapp in conjunction with other members to develop a new set of international controls for AR testing, QC and QA. Many new GC QC strains have now been thoroughly evaluated and will be included in three different "panels" named as follows, Provisional QC strains (intended to be used as a basic panel), Supplemental QC strains (to supplement the provisional panel in special cases), and Candidate QC strains (for identification of emerging resistance e.g. resistance to third generation cephalosporins). The evaluation of these QC strains is completed. Dr Knapp is close to finalising recommendations concerning the use of these new GC QC strains. The meeting acknowledged Dr Knapp for her contribution.

IV) Diagnostics, including molecular diagnostics

Trial of an automated method for GC PCR 

Dr Hannah Robertson presented her experiences from Scotland of using Roche GC PCR with subsequent confirmation by cppB gene and ompIII gene PCRs. By using this approach, they detect more GC positive samples in comparison with using solely GC culture. However, all positive samples with the Roche GC PCR need to be confirmed due to the high level of false positives and no data regarding the antimicrobial susceptibility of the GC strains are possible to receive.

Members commented that the need for supplemental testing in GC NAAT had been recognised with the CDC making recommendations in this regard. Australian approaches to this problem have been prepared and are in the final stages of approval.

Culture confirmation based on prolyliminopeptidase (PIP) and typing of Neisseria gonorrhoeae

Dr Magnus Unemo briefly described the function of the enzyme PIP (also named proline aminopeptidase among many other names), which is used for species confirmation of GC in several commercial kits. During recent years, PIP-negative GC isolates have been increasingly identified in many countries. These isolates are not species identified as GC in kits such as API NH, RapID NH, Gonochek II and Neisseria PET. An increased awareness of PIP-negative GC isolates is crucial and in several geographic areas worldwide, alterations in the diagnostic strategies may need to be considered. Dr Unemo also presented results from a phenotypic and genetic characterisation of PIP-negative GC isolates from United Kingdom, Denmark, Australia and New Zealand, which indicates a worldwide circulation, mainly among men who have sex with men, of at least one N. gonorrhoeae PIP-negative strain.

See also Abstract WP- 034 page 279 above and W0-101 page 96

of ISSTDR Abstract book or URL

V) Gonococcal typing

Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST) and developments

Dr Iona Martin described the molecular typing method NG-MAST, which sequences more variable segments of the porB gene and the tbpB gene. At present, there are at least 10 NG-MAST users around the world and a free webpage for designation of porB and tbpB allele numbers as well as NG-MAST sequence types (ST) has been developed. Further improvements of this webpage are also in progress, e.g. tools for creating sequence alignments and to look at single locus variation will be included.

Applications of GC typing to disease outbreaks

Dr Tapsall briefly presented the use of mainly phenotypical typing for identification of a DGI cluster.

Genetic Systems panel of monoclonal antibodies (MAbs) for serovar determination

Dr David Trees informed that it will be too time-consuming and difficult to develop new MAbs for replacements of the ones that cannot be supplied anymore. Probably, molecular methods for typing of GC will replace the serovar determination. However, if needed the “Pharmacia” panel of MAbs can still be used for serological characterization. This panel of MAbs is provided by Boule Diagnostics, Sweden.

Surveillance updates  

Dr Tapsall briefly described surveillance updates regarding GC AR in the Western Pacific Region. The resistance to ciprofloxacin is extremely high in many countries in this region. The MIC values to third generation cephalosporins are also increasing and an awareness of this has to be raised. The emergence of future ceftriaxone-resistance will be of major importance.

Re-structure of ICG

Dr Tapsall proposed a re-structure of ICG with a wider involvement and establishment of an "ICG Board" where all members can nominate a particular area of interest and involvement. Some people have already been contacted individually or nominated by others as a "Board member". It is important to have as wide involvement as possible regarding different areas of expertise and also geographically. If you have an area of special interest where you could contribute as a resource for ICG, please notify this. For the electronic communication of the members of the group, see below.

Further information on the reorganisation will follow.

Electronic communication

Dr Lai King Ng demonstrated the Canadian Public Health Agency communication system. This system includes a set of tools (e.g. News board, Group notification, Discussion board.) that the new structure of ICG will be allowed to use for a more effective communication. However, all members have to be registered as a user of the system. A template, i.e. Excel file, for registering users of the future ICG web tools has previously been distributed by Dr John Tapsall and after completing this form with all details, the file should be sent to Dr Lai King Ng (

WHO mapping facility for AMR in GC

This facility is still available but the mapping is done by groups in WHO not part of the AMR group. Thus the upgrading of AMR maps may be delayed due to resource limitation.

Discussion on an hypothesis advanced by Dr Livermore.

The proposition that targeted treatment for gonorrhoea was responsible for emergence and spread of quinolone resistance in GC was advanced by Dr Livermore (Lancet Infectious Diseases 2005;5:450-459). This paper was circulated prior to the meeting. Data was presented to show that alternative explanations exist to those proposed in the paper.

Next Meetings

Meeting at the International Union Against Sexually Transmitted Infections (IUSTI) Conference, Bangkok, Thailand (November 2005) and at the IPNC, Cairns, Australia (2006) are planned.