Standards for Laboratory Standards for Laboratory Diagnosis of TuberculosisDiagnosis of Tuberculosis

Professor Brian I. DuerdenProfessor Brian I. DuerdenInspector of Microbiology and Infection Inspector of Microbiology and Infection

Control,Control,Department of HealthDepartment of Health

TB diagnosis and management depend upon a reliable and prompt

laboratory service

Guidance and StandardsGuidance and Standards

National SOPNational SOP– How to do the testsHow to do the tests

NICE guidanceNICE guidance– How to manage the patientHow to manage the patient

DH programmeDH programme– What service should be deliveredWhat service should be delivered– 3 working groups3 working groups

TB monitoring and laboratory TB monitoring and laboratory services working groupservices working group

Surveillance standardsSurveillance standards

Standards for laboratory diagnosisStandards for laboratory diagnosis– Current best practiceCurrent best practice– Simple and straightforwardSimple and straightforward– Not replicate or replace the National SOPNot replicate or replace the National SOP

Standards to coverStandards to cover

SamplesSamples

Transfer to laboratoryTransfer to laboratory

Immediate testsImmediate tests– MicroscopyMicroscopy

Culture, isolation and Culture, isolation and identificationidentification

Laboratory facilities Laboratory facilities and expertiseand expertise

Transport Transport

Susceptibility testingSusceptibility testing

Molecular Molecular fingerprinting/typingfingerprinting/typing

NotificationNotification

PCR detection of MtbPCR detection of Mtb

Immunodiagnostic Immunodiagnostic teststests

Histopathology Histopathology

SamplesSamples

Type of sampleType of sample– Sputum (resp. sample), CSF (spinal/para-Sputum (resp. sample), CSF (spinal/para-

spinal/intra-cerebral), gastric washings, lymph spinal/intra-cerebral), gastric washings, lymph nodes (tissues), urine, faecesnodes (tissues), urine, faeces

Number of samplesNumber of samples– 2 or 3 for sputum? Consecutive days.2 or 3 for sputum? Consecutive days.– Early morning or any time?Early morning or any time?– True LRT specimenTrue LRT specimen

DocumentationDocumentation

Transfer to laboratoryTransfer to laboratory

Within 24h (or 1 working day, max 48h)Within 24h (or 1 working day, max 48h)– Minimise overgrowthMinimise overgrowth– Maintain AFB characterMaintain AFB character

Potentially infected clinical samplePotentially infected clinical sample– Routine procedureRoutine procedure

Immediate testsImmediate tests

MicroscopyMicroscopy– Auramine fluorescent stainingAuramine fluorescent staining– 6-day service (not on call)6-day service (not on call)– Perform microscopy and issue result within 24h (1 Perform microscopy and issue result within 24h (1

working day) of receiptworking day) of receipt– Telephone positive result to Telephone positive result to seniorsenior member of clinical member of clinical

teamteam– Notify lead TB nurse, lead clinician, CCDCNotify lead TB nurse, lead clinician, CCDC

Accreditation; IQC programme; satisfactory EQA Accreditation; IQC programme; satisfactory EQA performance; staff CPD/peer reviewperformance; staff CPD/peer review

Culture, isolation and identificationCulture, isolation and identification

Automated liquid culture on all samplesAutomated liquid culture on all samples– Set up within 24h of receipt (6 day service)Set up within 24h of receipt (6 day service)– Plus conventional solid culturePlus conventional solid culture

Send all isolates to RCM on day found to Send all isolates to RCM on day found to be positivebe positive– Reach RCM within 24h Reach RCM within 24h

Complete identification of most Complete identification of most mycobacterial isolates within 21 daysmycobacterial isolates within 21 days

Identification and reportingIdentification and reporting

NAAT (PCR, LCR) or hybridisation gene NAAT (PCR, LCR) or hybridisation gene probe for Mtb complexprobe for Mtb complex– On the day culture shows positive OROn the day culture shows positive OR– Within 24h of receipt at RCMWithin 24h of receipt at RCM

Other probes and/or phenotypic testsOther probes and/or phenotypic tests

Report on day of test to Report on day of test to – SeniorSenior member of clinical team member of clinical team– Lead TB nurse, lead TB clinician, CCDCLead TB nurse, lead TB clinician, CCDC

Laboratory facilities and expertiseLaboratory facilities and expertise

Safety – Category 3 for cultureSafety – Category 3 for culture– HSE approvedHSE approved– Contingency plan for accidental dispersalContingency plan for accidental dispersal– Continuity plan for closureContinuity plan for closure

AccreditedAccredited– IQC programme, satisfactory EQAIQC programme, satisfactory EQA

Sufficient number – daily service, Sufficient number – daily service, competencecompetenceNamed Consultant and BMS for adviceNamed Consultant and BMS for advice

TransportTransport

SamplesSamples– Potentially infected samples (routine)Potentially infected samples (routine)

Positive culturesPositive cultures– Category A but exemption to treat as B for Category A but exemption to treat as B for

clinical and diagnostic purposesclinical and diagnostic purposesUN 3373 – marked Diagnostic or Clinical UN 3373 – marked Diagnostic or Clinical

P650 packagingP650 packaging

Do not send by Royal MailDo not send by Royal Mail

Susceptibility testingSusceptibility testing

Complete within 30 days of initial receipt of Complete within 30 days of initial receipt of clinical sample for primary agentsclinical sample for primary agents– Isoniazid, rifampicin, pyrazinamide, ethambutolIsoniazid, rifampicin, pyrazinamide, ethambutol

Takes 10-20 days by liquid proportion (automated) or Takes 10-20 days by liquid proportion (automated) or resistance ratioresistance ratio

Molecular detectionMolecular detection– Rifampicin within 24h if MDRTB suspectedRifampicin within 24h if MDRTB suspected– Isoniazid under developmentIsoniazid under development

Done at RCM with accreditation, IQC, EQADone at RCM with accreditation, IQC, EQA

Molecular fingerprinting/typingMolecular fingerprinting/typing

ALL ISOLATESALL ISOLATES– 15-loci MIRU-VNTR15-loci MIRU-VNTR

Mycobacterial Interspersed Repetitive Units – Mycobacterial Interspersed Repetitive Units – Variable Number Tandem RepeatsVariable Number Tandem Repeats

– Results to national databaseResults to national database– Other techniques as appropriateOther techniques as appropriate

Done at RCMDone at RCM

Laboratory notification Laboratory notification

HPAHPA– Via CoSurv from laboratory that identifies a Via CoSurv from laboratory that identifies a

positive culturepositive culture– Confirmation of positive from RCM within 24h Confirmation of positive from RCM within 24h

(1 working day) of receipt(1 working day) of receipt– RCM reports culture and susceptibility results RCM reports culture and susceptibility results

to MycobNET within 24h of report to clinicianto MycobNET within 24h of report to clinician

PCR detection of MtbPCR detection of Mtb

Not routineNot routine

Available from RCM for particular samplesAvailable from RCM for particular samples– High suspicionHigh suspicion– Definitive diagnosis deemed to be urgentDefinitive diagnosis deemed to be urgent– Liaise in advance – Consultany Microbiologist Liaise in advance – Consultany Microbiologist

to RCM to RCM

Immunodiagnostic testsImmunodiagnostic tests

Interferon Interferon γγ (QuantiFERON-TB Gold) (QuantiFERON-TB Gold)

Activated specific T-cells (T-SPOT.Activated specific T-cells (T-SPOT.TBTB))

– Standard under developmentStandard under developmentWhich patients?Which patients?

How long should it take?How long should it take?

Who provides it?Who provides it?

What do the results mean and who interprets What do the results mean and who interprets them?them?

HistopathologyHistopathology

Report within 3 days of receiptReport within 3 days of receipt

Inform the Microbiology service Inform the Microbiology service – Ensure same reporting as for positive Ensure same reporting as for positive

microscopy and culture resultsmicroscopy and culture results

Send autopsy samples to Microbiology Send autopsy samples to Microbiology without formalinwithout formalin!!!!

[Role of PCR to be determined][Role of PCR to be determined]

Implementation of standardsImplementation of standards

Local responsibilityLocal responsibility– What is done where?What is done where?

Microscopy; culture; identificationMicroscopy; culture; identification

– What throughput is needed?What throughput is needed?– Equipment – cost-effectivenessEquipment – cost-effectiveness– Personnel Personnel

Maintain skills; CPD; peer reviewMaintain skills; CPD; peer reviewNamed individuals for adviceNamed individuals for adviceBack-up and coverBack-up and cover

– IQC, EQAIQC, EQA

Standards for QualityStandards for Quality

Only do what you can do properly!Only do what you can do properly!