kespro gonorrhoea
TRANSCRIPT
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Clinical Aspects ofClinical Aspects of
NAAT Testing forNAAT Testing for
NeisseriaNeisseria
GonorrhoeaGonorrhoea
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Neisseria GonorrhoeaNeisseria Gonorrhoea
Second most common bacterial STI in UKSecond most common bacterial STI in UK
Intracellular GramIntracellular Gram--ve diplococcusve diplococcus Obligate human pathogenObligate human pathogen
Colonises urogenital tractColonises urogenital tract
Uncomplicated mucosal infectionUncomplicated mucosal infection
Ascending infection of tractAscending infection of tract complicatedcomplicated
Rare, invasion into bloodRare, invasion into blood -- disseminateddisseminatedConjunctivitis / NeoConjunctivitis / Neo--natal conjunctivitisnatal conjunctivitis
Facilitates transmission of other STIs (HIV)Facilitates transmission of other STIs (HIV)
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Clinical ManifestationsClinical Manifestations
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Gonorrhoea EpidemiologyGonorrhoea Epidemiology
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Why Bother with NAAT for GC?Why Bother with NAAT for GC?
GUM attendancesGUM attendances year on yearyear on year
Many asymptomatic individuals wishing screeningMany asymptomatic individuals wishing screening 48 hr waiting targets by 200848 hr waiting targets by 2008
Multiple swabs replaced by single swab/urineMultiple swabs replaced by single swab/urine-- time saving to see more patientstime saving to see more patients
-- increased acceptability to patientsincreased acceptability to patients
Audit showed 38% males, 60% females to have aAudit showed 38% males, 60% females to have a
symptom or risk factorsymptom or risk factor-- halving the numbers of patients requiring GC cultureshalving the numbers of patients requiring GC cultures
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GC NAAT as Sole Test for GC?GC NAAT as Sole Test for GC?
GRASP data 2004 showed sig.GRASP data 2004 showed sig. increase in resistanceincrease in resistance-- >5% ciprofloxacin resistance all England/Wales>5% ciprofloxacin resistance all England/Wales-- 9% to 14%9% to 14% ciprofloxacin resistance 2003ciprofloxacin resistance 2003--20042004
Sufficient sample size to detect 5% resistance levelSufficient sample size to detect 5% resistance level
--high quality culture methods requiredhigh quality culture methods required
--need for adequate level of lab expertiseneed for adequate level of lab expertise
Currently unlicensed for other samples (rectum/pharynx)Currently unlicensed for other samples (rectum/pharynx)
Most rapid diagnosis made using microscopyMost rapid diagnosis made using microscopy
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Clinical Use of SDA Test forClinical Use of SDA Test for
GonorrhoeaGonorrhoea SDA test alone is not appropriate for screeningSDA test alone is not appropriate for screening
Certain individuals still need to be cultured.Certain individuals still need to be cultured.-- those identified as high risk for GCthose identified as high risk for GC
-- thosethose testing +ve following testing with SDA alone.testing +ve following testing with SDA alone.
From a retrospective audit carried out on clinical dataFrom a retrospective audit carried out on clinical data
from the trial patients using the criteria of risk factors andfrom the trial patients using the criteria of risk factors andsymptoms.symptoms.
-- only 4 individuals (all female) had no markers for possible GC (only 4 individuals (all female) had no markers for possible GC (7.4% of7.4% ofthe GC+ve group and 0.25% of all tested patients)the GC+ve group and 0.25% of all tested patients)
A protocol for the combined SDA test was set up, and itsA protocol for the combined SDA test was set up, and itsuse in clinical practice commenced 1/2/05.use in clinical practice commenced 1/2/05.
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Protocol for Use of the Combined SDAProtocol for Use of the Combined SDA
Test in Clinical PracticeTest in Clinical Practice
Risk Factor*
Symptom**
Sign
Full Screen
SDA only
Urine (m)Cervix (f)
Cultures
prior totreatment
No further
action
positive
negative positive
negative
*Risk Factors **Symptom
GC Contact Males
Past GC Diagnosis Discharge/Dysuria
MSM (Men who have sex with men) FemalesMSM Contact Discharge/Abnormal bleeding/
CSW (Commercial sex worker) Abdominal pain/Dysuria
CSW Contact
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Audit of the First Three Months ofAudit of the First Three Months of
Clinical PracticeClinical PracticeWe wished to evaluate the test by looking at:We wished to evaluate the test by looking at:
1.1. Concordance between SDA and cultures.Concordance between SDA and cultures.
2.2. Adherence to the protocol.Adherence to the protocol.
3.3. Adequacy of the protocol. ie. Low numbers ofAdequacy of the protocol. ie. Low numbers of
SDA +ve patients needing to be reSDA +ve patients needing to be re--tested.tested.
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Audit of First Three Months ClinicalAudit of First Three Months Clinical
UseUse A retrospective case note review of all gonorrhoea +veA retrospective case note review of all gonorrhoea +ve
patients, on any test (at all sites) between 1/2/05 andpatients, on any test (at all sites) between 1/2/05 and
30/4/05.30/4/05.
Data collected on sex, age, risk factors, symptoms, otherData collected on sex, age, risk factors, symptoms, other
STIs, consort data, and which tests were performed, ofSTIs, consort data, and which tests were performed, ofSDA, culture and microscopy.SDA, culture and microscopy.
A further 100 sets of GC negative case notes wasA further 100 sets of GC negative case notes wasreviewed, picked at random from the same time period.reviewed, picked at random from the same time period.Data was collected as to whether there were anyData was collected as to whether there were anydeviations from the protocol.deviations from the protocol.
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ResultsResults
Mean AgeMean Age Other STIsOther STIs Risk Factor/Risk Factor/
SymptomsSymptoms
Full ScreenFull Screen AsymptoAsympto
ScreenScreen
SDA+ve/SDA+ve/
Culture+veCulture+ve
SDA+ve/SDA+ve/
CultureCulture--veve
SDASDA--ve/ve/
Culture+veCulture+ve
MaleMale
(Total 62)(Total 62)
28.628.6 C4a 20 (32%)C4a 20 (32%)C11 1 (1.6%)C11 1 (1.6%)
A6 1 (1.6%)A6 1 (1.6%)
HIV 4 (6.5%)HIV 4 (6.5%)
59 (95%)59 (95%) 59 (95%)59 (95%)
(1 void)(1 void)
2 (3.2%)2 (3.2%) 49 (79%)49 (79%) 2 (3.2%)2 (3.2%) 7 (11.2%)7 (11.2%)
FemaleFemale(Total 44)(Total 44)
21.621.6 C4a 19 (43%)C4a 19 (43%)C6a 4 (9.1%)C6a 4 (9.1%)
38 (86.3%)38 (86.3%) 39 (88.6%)39 (88.6%)(2 void)(2 void)
3 (6.8%)3 (6.8%) 33 (75%)33 (75%) 3 (6.8%)3 (6.8%) 3 (6.8%)3 (6.8%)
3328 patients were tested for Gonorrhoea between 1/2 - 30/4 2005.106 tested positive, (62 males and 45 females.)
Table 1. Results from GC Posit ive Group
Of 98 patients tested with both SDA and culture:
- SDA+ve/Culture+ve results in 82 (83.7%). 83% males/85% females.
- SDA-ve/Culture+ve results found in 10. (7 males and 3 females)
-All 7 males were MSM, culture positive at rectal or pharyngeal sites.
- 4 were also GC contacts.- Of the 3 women, 2 were positive at rectal site only.- 1 was culture positive at urethral site only (a false negative).
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Table 2. SDA+ve/CultureTable 2. SDA+ve/Culture--ve Resultsve Results
Risk FactorRisk Factor SymptomSymptom MicroscopyMicroscopy Other Culture InfoOther Culture Info Consort GCConsort GC
PositivePositive
MalesMales 1.1. MSMMSM NoNo Positive(Ur)Positive(Ur) NoneNone UnknownUnknown
2.2. MSMMSM NoNo Positive(Ur)Positive(Ur) +ve on re+ve on re--examexam PositivePositive
* * 3.* * 3. NoNo NoNo Not doneNot done SDA onlySDA only NegativeNegative
* * 4.* * 4. NoNo NoNo Not doneNot done SDA onlySDA only NegativeNegative
FemalesFemales 1.1. Misc.Misc. NoNo NegativeNegative +ve placenta culture+ve placenta culture NegativeNegative
2.2. NoNo YesYes PositivePositive NoneNone PositivePositive** 3.** 3. NoNo NoNo NegativeNegative NoneNone NegativeNegative
4.4. NoNo NoNo Not doneNot done SDA onlySDA only PositivePositive
5.5. NoNo NoNo Not doneNot done SDA onlySDA only PositivePositive
6.6. NoNo NoNo NegativeNegative Culture +ve on reCulture +ve on re--callcall NegativeNegative
10/106 results were SDA positive with cultures negative or unavailable.
Of these 10, 7 had other features that were consistent with a GC diagnosis.
**3 likely false posit ive SDA results, 2 males, 1 female. (BUT 2 unconfirmed)
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Adequacy of the ProtocolAdequacy of the Protocol
Ability of protocol toAbility of protocol to predict need for cultures in thosepredict need for cultures in those
with GCwith GC
-- 55 patients with no RF/symptoms subsequently tested GC+ve on SDApatients with no RF/symptoms subsequently tested GC+ve on SDA
-- 4.7% of the +ve cases and 0.15% of the tested population4.7% of the +ve cases and 0.15% of the tested population
-- less than the projected number of reless than the projected number of re--calls (7.4% of +ves, 0.25% of allcalls (7.4% of +ves, 0.25% of all
patients)patients)
Ease of adherence to protocolEase of adherence to protocol
GC+ve GroupGC+ve Group -- allall patients with RF/symptoms screened by culture/SDApatients with RF/symptoms screened by culture/SDA-- 2 inappropriate cultures. 3 incomplete set of tests2 inappropriate cultures. 3 incomplete set of tests
-- 4/5 SDA only screens NOT cultured pre4/5 SDA only screens NOT cultured pre--treatmenttreatment
GCGC--ve Groupve Group 5/100 audited case notes SDA alone sent inappropriately5/100 audited case notes SDA alone sent inappropriately
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Urethral Only GC Infection in FemalesUrethral Only GC Infection in Females
From our study, 2 (7.4%) of 27 GC+ve women found to be culture+ve aturethral site only
1 of these women (asymptomatic/no risk factors) was cervical SDA-ve
- a false negative (In women cervix SDA replaces cervical and urethral culture)
1978 study*, 6% of 607 GC+ve women at a London GUM clinic had singlesite urethral gonorrhoea infection
SDA picks up some of these.
Urethral + cervical culture clinical standard in UK
Larger studies needed to examine how many urethral GC single siteinfections missed?
Additional urine/urethral swabs in women clinically and economicallyfeasible?
*Barlow, Phillips. Lancet. April 1978, 761-764
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Changes in Clinical PracticeChanges in Clinical Practice
Less time spent on swabbing and microscopyLess time spent on swabbing and microscopy
frees doctors and nurses to see more patientsfrees doctors and nurses to see more patients
Rapid screening of asymptomatic patients in routineRapid screening of asymptomatic patients in routine
clinicsclinics
Introduction of fastIntroduction of fast--track asymptomatic screening clinictrack asymptomatic screening clinic-- maximised patient numbers, minimal staffmaximised patient numbers, minimal staff
Audit of clinical practiceAudit of clinical practice May 2005May 2005 Nov 2005Nov 2005
48hr access improved from 24%48hr access improved from 24% -- 40%40%increase in acceptability of tests (in men especially)increase in acceptability of tests (in men especially)
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Summary of GC SDASummary of GC SDA
Sensitive/Specific test in our study populationSensitive/Specific test in our study population
Low numbers of false positives in clinical practiceLow numbers of false positives in clinical practice
Single site urethral GC in women, an issue?Single site urethral GC in women, an issue?
PPV is high in our populationPPV is high in our population
This can vary in different populationsThis can vary in different populations
Anxiety remains about poor PPVs in low prevalence populationsAnxiety remains about poor PPVs in low prevalence populations
Need remains for culture alongside SDANeed remains for culture alongside SDAwith a suitable protocol for the target population which can bewith a suitable protocol for the target population which can be easilyeasilyfollowedfollowed
Can result in significantCan result in significant in clinical/lab workloadin clinical/lab workload
Cost neutral in terms of lab/test costsCost neutral in terms of lab/test costs
Increased clinical efficiencyIncreased clinical efficiency greater patient throughputgreater patient throughput