kespro gonorrhoea

7/30/2019 Kespro Gonorrhoea

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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

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