Guidance

GRASP protocol

Updated 10 May 2023

1. Introduction

1.1 Background

Gonorrhoea, caused by the bacterium Neisseria gonorrhoeae, is the second-most common sexually transmitted infection (STI) diagnosed in the UK. If untreated, gonorrhoea can lead to complications in women, such as:

• chronic pelvic pain
• pelvic inflammatory disease
• ectopic pregnancy
• infertility

The emergence of resistance to antimicrobials used to treat gonorrhoea is a global public health concern. The ability of gonorrhoea to successively develop resistance to different antimicrobials has hampered control efforts and risks the disease becoming untreatable. Surveillance of antimicrobial resistance (AMR) is critical for informing national treatment guidelines to ensure appropriate patient management. Established in 2000, the gonococcal resistance to antimicrobials surveillance programme (GRASP) includes a suite of testing and surveillance systems to detect and monitor AMR in N. gonorrhoeae and potential treatment failures.

The cornerstone of GRASP is a national sentinel surveillance system. The GRASP sentinel surveillance system involves the collection of N. gonorrhoeae isolates from consecutive individuals attending a network of 27 sexual health services (SHSs) across England and Wales and their 21 associated laboratories, typically between July and September annually.

Since 2000, GRASP data have revealed important antimicrobial susceptibility trends and provided evidence to revise national treatment guidelines in 2005, 2011 and 2019.

1.2 Objectives

The objectives of GRASP are to:

• characterise annual antimicrobial susceptibility patterns in N. gonorrhoeae in England and Wales, and monitor trends over time
• identify associations between antimicrobial resistant gonococci and patient demographic, clinical and behavioural data
• inform the development of national gonorrhoea treatment guidelines
• apply molecular typing and characterisation to further investigate any emerging resistance trends

2. Methods

GRASP is a collaboration between the:

• Blood Safety, Hepatitis, Sexually Transmitted Infections and HIV (BSHSH) Division, part of the Clinical and Public Health (CPH) group at the UK Health Security Agency (UKHSA)
• Antimicrobial Resistance in STIs (AMRSTI) section, part of the Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit, UKHSA
• 27 SHSs throughout England and Wales and the 21 associated regional primary diagnostic laboratories

Analyses from the GRASP sentinel surveillance system are based on:

• antimicrobial susceptibility data from isolates collected from consecutive individuals with a gonorrhoea diagnosis at a sentinel SHS during the collection periods
• demographic, clinical and behavioural information from these individuals

Data from the sentinel surveillance system are supplemented year-round by real-time laboratory data reported through the Second-Generation Surveillance System (SGSS). SGSS includes unconfirmed gonococcal antimicrobial susceptibility data from testing undertaken in primary diagnostic laboratories across England. In addition, AMRSTI receives gonococcal isolates for susceptibility testing and confirmation of identity from primary diagnostic laboratories. Data on suspected treatment failures, reported to UKHSA via the HIV and STI Data Exchange, also feed into GRASP.

3. Activities and responsibilities

3.1 Sentinel sites overview

A GRASP sentinel SHS is responsible for the collection and submission of:

• gonococcal isolates from consecutive individuals to its primary diagnostic laboratory during the collection period (usually July to September)
• demographic, clinical and behavioural data on individuals diagnosed with gonorrhoea in their SHS to UKHSA

Gonorrhoea diagnoses made during the survey period from GRASP SHSs in England are extracted from the national STI surveillance dataset, the GUMCAD STI surveillance system (version 3), and linked to an electronic web-reporting form on the HIV and STI Data Exchange.

Participating SHSs access the form securely online to provide additional demographic, behavioural and antimicrobial prescribing data for GRASP. For participating SHSs in Wales, demographic, clinical and behavioural data for individuals captured in GRASP are reported via an electronic spreadsheet.

3.2 Sentinels site laboratory collection, handling and shipping of isolates

Isolates of N. gonorrhoeae are archived on cryobeads and are stored at -80°C. Frozen archives are collected via courier and are shipped on dry ice to UKHSA at designated times during the collection period, dictated by the number of isolates collected.

Prior to the start of the collection period, GRASP scientists estimate the number of isolates expected from collaborating laboratories on the basis of previous years submissions. Collection packs, comprising cryobeads, labels pre-printed with unique study numbers, the laboratory isolate collection protocol, a line listing form and the list of participating SHSs, are then distributed to all collaborating laboratories. Collection packs and courier shipments are provided and organised free-of-charge by UKHSA.

3.3 Sentinel site clinic activities

GRASP demographic, clinical and behavioural data collections are based upon GUMCADv3 data submissions. All gonorrhoea diagnoses made and reported via GUMCADv3 are linked to an electronic web reporting form on UKHSA’s HIV and STI Data Exchange. The following fields are pulled directly from GUMCADv3 submissions and will already be completed in the reporting form:

• date of attendance
• attendance type
• gender
• age
• ethnicity
• country of birth
• sexual orientation
• concurrent STIs

GRASP clinic staff then enhance these data with additional demographic, clinical and behavioural data items obtained through review of patient medical records, including:

• date of birth
• diagnostic method(s) used
• site(s) of infection and symptom presence
• previous gonorrhoea diagnoses
• HIV status
• antibiotic treatment for gonorrhoea and chlamydia
• test of cure
• sexual contacts (in the UK or abroad)

4. Testing of isolates for antimicrobial susceptibility

Regional primary diagnostic laboratories are responsible for sending isolates received from GRASP SHSs to the UKHSA AMRSTI national reference laboratory.

4.1 Receipt of isolates

Once isolates are received at UKHSA they are matched to the accompanying electronic line listing and any discrepancies identified are followed up with the submitting laboratory. Isolates are then entered into an electronic database. Isolates are stored at -80°C prior to testing.

4.2 Confirmatory testing

The identification of all isolates submitted to GRASP are confirmed using Gram stain (Gram-negative diplococci), oxidase test (where positive) and N. gonorrhoeae-specific real-time PCR (RT-PCR).

Due to the high-throughput nature of GRASP, lysates are made directly from cryobeads for testing on the RT-PCR. The assay specifically targets the N. gonorrhoeae porA gene which encodes the highly conserved, non-expressed porin-A protein. The assay also targets the sodC gene (which encodes a protein required for ion transport and metabolism) of Neisseria meningitidis, allowing for direct detection of mis-identified isolates. There is evidence that some N. gonorrhoeae isolates have recombined with N. meningitidis and carry the N. meningitidis porA sequence, therefore any isolates that are negative for both gene targets are identified further using MALDI-ToF analysis. Isolates requiring MALDI-ToF analysis are first extracted using formic acid. Isolates with an identification score >2.3 are considered acceptable. Isolates whose MALDI-ToF score is repeatedly <2.3 are tested by API-NH (Biomerieux) to obtain a biochemical profile.

4.3 Beta-lactamase tests

β-lactamase activity is measured using Nitrocefin (Oxoid), a chromogenic cephalosporin substrate. Isolates exhibiting β-lactamase activity rapidly catalyse the reagent inducing a colour change from yellow to red.

4.4 Antimicrobial susceptibility testing

Susceptibilities to 8 different antimicrobials (penicillin, tetracycline, ceftriaxone, cefixime, azithromycin, ciprofloxacin, spectinomycin and gentamicin) are ascertained for each isolate submitted to GRASP that can be case-matched within the GUMCAD STI Surveillance System and to enhanced data provided by SHSs. Where more than one isolate is collected from an individual diagnosed with gonorrhoea, the following prioritisation hierarchy is applied for testing:

1. pharyngeal*
2. male rectal
3. male urethral
4. female cervical
5. any other site

*Please note that the 2021 collection is the first year that pharyngeal isolates have been prioritised ahead of all other sites due to concerns that resistance is most likely to emerge in this site.

Testing is carried out by agar dilution using Diagnostic Sensitivity Test (DST) agar plus 5% lysed horse blood and 1% Vitox (Oxoid).

Susceptibility testing plates are quality controlled using a panel of control isolates with well characterised antimicrobial susceptibility profiles. Plates that pass quality control are used for the testing of GRASP isolates. Inoculated plates are incubated for 48 hours before reading using an automated plate reader.

Since 2016, breakpoint plates have been used for susceptibility testing of ciprofloxacin and spectinomycin. Breakpoint plates were introduced for penicillin in 2017 and tetracycline in 2018.

4.5 Alert value MICs

Alert minimum inhibitory concentrations (MICs) are:

• >0.25 mg/L of cefixime
• >0.25 mg/L of ceftriaxone
• >4 mg/L of azithromycin
• >64 mg/L of spectinomycin

Isolates are tested by E-test (Biomerieux) to confirm the MIC. Where the penicillin MIC >2 mg/L, a negative nitrocefin result should be questioned and investigated. N. gonorrhoeae exhibiting resistance to cefixime (>0.125 mg/L) are unlikely to be susceptible to ciprofloxacin; any isolates exhibiting this profile should be investigated further.

4.6 Archive isolates

Isolates are submitted to GRASP on cryobeads. Therefore, further archiving is not necessary for most isolates. Where contamination was identified on sub-culture or where isolates were more fastidious, purified isolates are re-archived on cryobeads.

4.7 Isolate preservation

All isolates of N. gonorrhoeae are stored at -80°C to preserve viability.

5. Ethics

GRASP is a routine public health surveillance activity, and no specific consent is required from individuals captured within it.

UKHSA has permission to handle data obtained by GRASP under Section 251 of the UK National Health Service Act of 2006 (previously Section 60 of the Health and Social Care Act of 2001), which was renewed annually by the ethics and confidentiality committee of the National Information Governance Board until 2013. Since then, the power of approval of public health surveillance activity has been granted directly to UKHSA.

6. Data reporting

There are several outputs related to the reporting of findings from GRASP. These include:

• the annual GRASP report, produced within the year following the data collection period
• the annual GRASP collaborators’ meeting, which features presentations and discussions of the latest data on antimicrobial resistance in N. gonorrhoeae
• clinic and laboratory-specific reports, comprising data on local gonorrhoea diagnoses and resistance trends for all GRASP participating sites*

*A shortened report will be provided where less than 20 diagnoses were included from a participating clinic in the GRASP year and this data will also be masked when reporting longitudinal trends in subsequent years; this is due to difficulties interpreting the data where numbers are small.

These outputs are disseminated via:

• Health Protection Reports (HPR): annual report on the prevalence of antimicrobial resistance in England and Wales
• peer-reviewed articles: anticipated that articles will be produced for dissemination in peer-reviewed medical journals
• oral and poster presentation: anticipated presentations of GRASP findings to end-users (including sexual health, public health and microbiology specialties) at appropriate fora (for example conferences, meetings, special interest groups)
• internet: presentation of summary data on the GOV.UK website

7. Use of GRASP isolates and data

The GRASP dataset draws data from GUMCADv3. Therefore, UKHSA staff seeking access to GRASP data must complete a GUMCADv3 data request form detailing the purpose of the request and the data that are required. Typically, a new form is required for each new analysis planned. Once completed, the form should be sent to grasp.enquiries@ukhsa.gov.uk for review. The request will be discussed with the GRASP team and the GRASP Steering Group where appropriate.

If the requestor is not a member of UKHSA staff, then:

• an honorary contract must be set up for an employee of another organisation who is coming to complete work or a project with UKHSA (for example University College London or St. George’s)
• a visiting worker’s agreement must be set up if the requestor does not have a principal employer (for example an MSc student)