point of care testing and microbiology
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Point of Care Testing and Microbiology. Yvette S. McCarter, PhD, DABMM Director, Clinical Microbiology Laboratory University of Florida Health Science Center-Jacksonville Jacksonville, FL Clinical Associate Professor of Pathology University of Florida College of Medicine. - PowerPoint PPT PresentationTRANSCRIPT
Point of Care Testing and Microbiology
Yvette S. McCarter, PhD, DABMMYvette S. McCarter, PhD, DABMMDirector, Clinical Microbiology LaboratoryDirector, Clinical Microbiology Laboratory
University of Florida Health Science Center-JacksonvilleUniversity of Florida Health Science Center-Jacksonville
Jacksonville, FLJacksonville, FL
Clinical Associate Professor of PathologyClinical Associate Professor of Pathology
University of Florida College of MedicineUniversity of Florida College of Medicine
Point of Care Testing and Microbiology
ObjectivesObjectives Historical PerspectiveHistorical Perspective POCT – Clinically-relevant? Cost-POCT – Clinically-relevant? Cost-
effective?effective? Currently available Microbiology POCTCurrently available Microbiology POCT Advantages and disadvantages of Advantages and disadvantages of
Microbiology POCTMicrobiology POCT
Point of Care Testing
Historical PerspectiveHistorical Perspective
Clinical Ward Laboratory TestingClinical Ward Laboratory Testing
Centralized Laboratory TestingCentralized Laboratory Testing
Point of Care TestingPoint of Care Testing
Test Life Cycle
Centralized LabCentralized Lab Test orderedTest ordered Test request processedTest request processed Specimen obtainedSpecimen obtained Specimen transported to labSpecimen transported to lab Specimen processed by labSpecimen processed by lab Specimen analyzedSpecimen analyzed Results reviewed by lab staffResults reviewed by lab staff Results reported to clinicianResults reported to clinician Clinician acts on resultsClinician acts on results
Point of CarePoint of Care Test orderedTest ordered Specimen obtainedSpecimen obtained Specimen analyzedSpecimen analyzed Clinician acts on resultClinician acts on result
Why is Point of Care testing a clinically Why is Point of Care testing a clinically relevant alternative to centralized relevant alternative to centralized
testing?testing?
Decreased Turnaround TimeDecreased Turnaround Time
Why decreased turnaround time?Why decreased turnaround time?
Elimination of specimen transport Elimination of specimen transport and processing timeand processing time
Transport/Processing Time vs. Analysis Time
0
5
10
15
20
25
30
35
40
BloodGases
K+/Na+ Hematocrit
TA
T (
min
)
Analysis Time
Transport/Processing Time
Salem et al. JAMA 1991; 266:382-389
Clinical Benefits of Decreased Turnaround Time
Evidence-based medical decisions in Evidence-based medical decisions in “real time”“real time”
Eliminates need for ordering additional, Eliminates need for ordering additional, unnecessary testsunnecessary tests
Reduction in unneeded medicationsReduction in unneeded medications Decrease in physician “switching”Decrease in physician “switching” Perceived patient benefitsPerceived patient benefits
Economic Considerations
COST!!!!COST!!!!
Look beyond “cost per test”Look beyond “cost per test” Judge cost-effectiveness in the context Judge cost-effectiveness in the context
of “total cost of patient care”of “total cost of patient care”
Why is Point of Care testing a cost-Why is Point of Care testing a cost-effective alternative to centralized effective alternative to centralized
testing?testing?
Decreased Turnaround TimeDecreased Turnaround Time
Economic Benefits of Decreased Turnaround Time
Reduction in duplicate test ordersReduction in duplicate test orders Reduced consumption of other Reduced consumption of other
expensive services/products (lab tests, expensive services/products (lab tests, pharmaceuticals)pharmaceuticals)
Decreased length of stayDecreased length of stay
Economic Benefits of Decreased Turnaround Time
Point of Care Testing in the Post Point of Care Testing in the Post Anesthesia Care UnitAnesthesia Care Unit
Use of POCT resulted in:Use of POCT resulted in: reduced test TAT from 26 min to 2 reduced test TAT from 26 min to 2
minmin decreased length of stay by 18 mindecreased length of stay by 18 min documented cost savings due to documented cost savings due to
decreased length of staydecreased length of stay
GoodwinGoodwin MLO 1994; 26 (9S):15-18. MLO 1994; 26 (9S):15-18.
MicrobiologyMicrobiology
Point of Care TestingPoint of Care Testing
““Your scientists were so preoccupied with Your scientists were so preoccupied with whether or not they whether or not they couldcould, they didn't , they didn't
stop to think if they stop to think if they shouldshould.”.”
-Dr. Ian Malcolm-Dr. Ian Malcolm
Jurassic ParkJurassic Park
Why do we need it?
Evidence-based medical decisions in “real Evidence-based medical decisions in “real time”time”
Eliminates need for ordering additional, Eliminates need for ordering additional, unnecessary testsunnecessary tests
Reduction in unneeded medicationsReduction in unneeded medications ““Perceived” patient benefitsPerceived” patient benefits Reduction in duplicate test ordersReduction in duplicate test orders Reduced consumption of other expensive Reduced consumption of other expensive
services/products (lab tests, pharmaceuticals)services/products (lab tests, pharmaceuticals)
What to consider…
Choose the appropriate testChoose the appropriate test Difficulty?Difficulty? Necessary skill level?Necessary skill level? How much QC?How much QC?
TrainingTraining See one, do one, teach one See one, do one, teach one
Procedure Procedure Don’t assumeDon’t assume Pictures Pictures
Microbiology Point of Care Testing
Most commonMost common Group A streptococcal pharyngitisGroup A streptococcal pharyngitis HelicobacterHelicobacter pyloripylori antibody antibody HelicobacterHelicobacter pyloripylori HIV antibodyHIV antibody Provider Performed MicroscopyProvider Performed Microscopy
Skin KOHSkin KOHVaginal KOHVaginal KOHVaginal wet prepsVaginal wet preps
Microbiology Point of Care Testing
Additional testing availableAdditional testing available Influenza A, B and A/BInfluenza A, B and A/B Infectious mononucleosisInfectious mononucleosis Lyme antibodyLyme antibody Respiratory syncytial virusRespiratory syncytial virus Pinworm prepsPinworm preps Gram stainGram stain
Group A Streptococcal Pharyngitis
Acute pharyngitis=most frequent reason Acute pharyngitis=most frequent reason for pediatrician and PCP visitsfor pediatrician and PCP visits Most pharyngitis viral in originMost pharyngitis viral in origin Group A strep Group A strep 15% of pharyngitis 15% of pharyngitis
cases in childrencases in children Difficult to distinguish streptococcal and Difficult to distinguish streptococcal and
non-streptococcal diseasenon-streptococcal disease
Group A Streptococcal Pharyngitis
Group A Streptococcal Pharyngitis
Group A Streptococcal Pharyngitis
Early recognition and treatment importantEarly recognition and treatment important Shorten duration of clinical illnessShorten duration of clinical illness Prevent transmissionPrevent transmission Prevent sequelaePrevent sequelae
Rheumatic heart diseaseRheumatic heart diseaseGlomerulonephritis Glomerulonephritis
Group A Streptococcal Pharyngitis - Diagnosis
CultureCulture Gold standardGold standard 24-48 hr result24-48 hr result
Rapid antigen testsRapid antigen tests Enzyme immunoassays (POCT)Enzyme immunoassays (POCT) Optical immunoassaysOptical immunoassays
Nucleic acid based testsNucleic acid based tests
Group A Streptococcal Pharyngitis - POCT
Pediatric SettingPediatric Setting Evaluated 2401 patients with Evaluated 2401 patients with
suspected streptococcal pharyngitis suspected streptococcal pharyngitis with rapid latex test and culturewith rapid latex test and culture
ConclusionsConclusionsRapid test available while patient Rapid test available while patient
on-siteon-siteSame day Rx in 90% of patientsSame day Rx in 90% of patients
Wiedermann et al. J Am Board Fam Pract 1991; 4:79-82
Group A Streptococcal Pharyngitis - POCT
Emergency DepartmentEmergency Department Compared clinical judgment vs. rapid testing Compared clinical judgment vs. rapid testing
for diagnosis of pharyngitis in 147 patientsfor diagnosis of pharyngitis in 147 patients ConclusionsConclusions
Rapid test significantly better than clinical Rapid test significantly better than clinical judgment for determining diseasejudgment for determining disease
Rapid test eliminates problems/costs of empiric Rapid test eliminates problems/costs of empiric Rx and patient follow-up complianceRx and patient follow-up compliance
Only 14% of patients followed up on culturesOnly 14% of patients followed up on cultures
DuBois et al. Ann Emerg Med 1986; 15:157-159
Group A Streptococcal Pharyngitis - POCT
Primary Care SettingPrimary Care Setting Studied impact of rapid test on physician Studied impact of rapid test on physician
prescribing patternsprescribing patterns ConclusionsConclusions
Antibiotic prescribing patterns changed when Antibiotic prescribing patterns changed when rapid test usedrapid test used
Physicians initiated Rx with positive result and Physicians initiated Rx with positive result and waited for culture before initiating Rx with waited for culture before initiating Rx with negative resultnegative result
• Reduced inappropriate antibiotic usageReduced inappropriate antibiotic usage• Reduced unnecessary cost and antibiotic exposureReduced unnecessary cost and antibiotic exposure
True et al. J Fam Prac 1986; 23:215-219
Group A Streptococcal Pharyngitis - POCT
37 CLIA “waived” 37 CLIA “waived” teststests Abbott SignifyAbbott Signify Biostar AcceavaBiostar Acceava Binax NOWBinax NOW Quidel QuickVueQuidel QuickVue BD LINKBD LINK Meridian Meridian
ImmunoCardImmunoCard
Group A Streptococcal Pharyngitis - POCT
AdvantagesAdvantages Results in 5 minResults in 5 min Internal controlsInternal controls Clear endpointsClear endpoints
DisadvantagesDisadvantages Sensitivities lower Sensitivities lower
than company than company claimsclaims
Group A Streptococcal Pharyngitis - POCT
Things to remember…Things to remember… Verification of test against cultureVerification of test against culture Culture all negative testsCulture all negative tests
Rapid test collection swab often Rapid test collection swab often different from culture swabdifferent from culture swab
Helicobacter pylori Infection
Early 1980s link between Early 1980s link between H. pyloriH. pylori and peptic and peptic ulcer disease/gastric cancer establishedulcer disease/gastric cancer established
EpidemiologyEpidemiology Up to 50% of world’s population infectedUp to 50% of world’s population infected Fecal-oral and oral-oral spreadFecal-oral and oral-oral spread Prevalence of infection increases with age Prevalence of infection increases with age
(developed countries)(developed countries)
Helicobacter pylori Infection
PathologyPathology Lives under protective mucous layerLives under protective mucous layer Acute gastritis chronic active gastritisAcute gastritis chronic active gastritis
Duodenal ulcerDuodenal ulcer MALT lymphomaMALT lymphoma Gastric ulcerGastric ulcer Gastric carcinomaGastric carcinoma
Helicobacter pylori Infection
Helicobacter pylori Diagnostic Methods
NoninvasiveNoninvasive Antibody detectionAntibody detection
IgG (POCT)IgG (POCT)IgAIgA
Urea breath testUrea breath test Stool antigenStool antigen
Helicobacter pylori Diagnostic Methods
InvasiveInvasive Biopsy (multiple required)Biopsy (multiple required)
HistopathologyHistopathology
• Silver or Warthin-Starry stainsSilver or Warthin-Starry stainsRapid urease testing (POCT)Rapid urease testing (POCT)
• Agar based gel or paper stripAgar based gel or paper stripCulture Culture
Helicobacter pylori POCT
BiopsyBiopsy 7 CLIA “waived” tests7 CLIA “waived” tests
Serim PyloriTekSerim PyloriTekCLOtestCLOtestChek-Med Systems HP OneChek-Med Systems HP One
SerologySerology 18 CLIA “waived” tests18 CLIA “waived” tests
Meridian ImmunoCard STATMeridian ImmunoCard STATAbbott SignifyAbbott SignifyQuidel QuickVueQuidel QuickVue
Helicobacter pylori POCT
Helicobacter pylori POCT
Helicobacter pylori POCT
AdvantagesAdvantages Rapid resultsRapid results
15 min-24 hr15 min-24 hr Internal controlsInternal controls Room Room
temperature temperature storage and storage and incubationincubation
DisadvantagesDisadvantages Potential for false Potential for false
negativesnegatives
Rapid Urease Testing
Helicobacter pylori POCT
AdvantagesAdvantages Rapid resultsRapid results
5 min5 min Built in controlsBuilt in controls External controlsExternal controls Room Room
temperature temperature storagestorage
DisadvantagesDisadvantages Whole blood less Whole blood less
sensitive than sensitive than serumserum
Antibody Detection
HIV InfectionThe VirusThe Virus
RetrovirusRetrovirus Bar-shaped coreBar-shaped core 2 short strands of RNA2 short strands of RNA EnzymesEnzymes
Reverse transcriptaseReverse transcriptase ProteaseProtease RibonucleaseRibonuclease IntegraseIntegrase
Outer lipid envelope containing an antigen Outer lipid envelope containing an antigen (gp160) that helps virus bind to CD4 cells(gp160) that helps virus bind to CD4 cells
A global view of HIV infection 33 million adults living with HIV/AIDS as of end 1999
Adult prevalence rate
15.0% – 36.0% 5.0% – 15.0% 1.0% – 5.0% 0.5% – 1.0% 0.1% – 0.5% 0.0% – 0.1% not available
Diagnosis of HIV
CultureCulture Rarely performedRarely performed
Serology - Gold StandardSerology - Gold Standard Sensitive EIASensitive EIA Confirmatory Western blotConfirmatory Western blot
Window periodWindow period P24 antigenP24 antigen PCRPCR
Diagnosis of HIV Alternative Fluids and Home CollectionAlternative Fluids and Home Collection
OraSureOraSure Oral mucosal transudate - serum derived fluid, enters saliva Oral mucosal transudate - serum derived fluid, enters saliva
from gingival crevices, contains antibodyfrom gingival crevices, contains antibody• Can be used for EIA and Western blot testing, comparable Can be used for EIA and Western blot testing, comparable
sensitivity to serumsensitivity to serum Calypte (Sentinel)Calypte (Sentinel)
UrineUrine• Lower sensitivity and specificity than serum for diagnosisLower sensitivity and specificity than serum for diagnosis• No FDA licensed Western blotNo FDA licensed Western blot
Home AccessHome Access Finger stick, mail in blood spot for testingFinger stick, mail in blood spot for testing Pre and post test counselingPre and post test counseling Problem with improperly collected specimensProblem with improperly collected specimens
Diagnosis of HIV - POCT
1 CLIA “waived” test1 CLIA “waived” test OraQuick Rapid OraQuick Rapid
HIV-1 Antibody HIV-1 Antibody TestTest
Diagnosis of HIV - POCT
Public Health SettingPublic Health Setting Evaluated 1923 samples from STD clinics and Evaluated 1923 samples from STD clinics and
HIV counseling centers using SUDS and HIV counseling centers using SUDS and conventional EIA / WBconventional EIA / WB
ConclusionsConclusions SUDS sensitivity 100%, PPV 88% (STD), PPV SUDS sensitivity 100%, PPV 88% (STD), PPV
81% (HIV)81% (HIV) Rapid testing feasible in public health settings Rapid testing feasible in public health settings
(accurate, reasonable cost, results during visit)(accurate, reasonable cost, results during visit)
Kassler et al. J Clin Microbiol 1995: 33:2899-2902
Diagnosis of HIV - POCT
Labor and DeliveryLabor and Delivery Evaluated 380 women presenting with Evaluated 380 women presenting with
unknown HIV statusunknown HIV status Compared OraQuick performed in L&D and Compared OraQuick performed in L&D and
lablab ConclusionsConclusions
Median TAT POCT=45 min, lab=3.5 hrMedian TAT POCT=45 min, lab=3.5 hrMore rapid implementation of antiviral More rapid implementation of antiviral
Rx with POCTRx with POCT
MMWR 2003; 52:866-868
Diagnosis of HIV - POCT
Appropriate settingsAppropriate settings Evaluation of needlestick exposuresEvaluation of needlestick exposures Labor and DeliveryLabor and Delivery
Previously untested for HIVPreviously untested for HIV Public HealthPublic Health
STD clinicsSTD clinicsHIV counseling centersHIV counseling centersEDED
Diagnosis of HIV - POCT
AdvantagesAdvantages Rapid resultsRapid results
CounselingCounselingRxRx
Internal controlsInternal controls AccurateAccurate
DisadvantagesDisadvantages Must confirm Must confirm
positive resultspositive results ““Restrictions”Restrictions”
Diagnosis of HIV - POCT
RestrictionsRestrictions Sale restricted to clinical laboratoriesSale restricted to clinical laboratories
that have an adequate QA program; andthat have an adequate QA program; and where there is assurance operators will receive and where there is assurance operators will receive and
use instructional materialsuse instructional materials Approved only for use by an agent of a clinical Approved only for use by an agent of a clinical
laboratorylaboratory Test subjects must receive “Subject Information” Test subjects must receive “Subject Information”
prior to collection and appropriate information prior to collection and appropriate information when results are providedwhen results are provided
Not approved to screen blood or tissue donorsNot approved to screen blood or tissue donors
Diagnosis of HIV - POCT
Things to think about…Things to think about… Can a central lab give you adequate Can a central lab give you adequate
TAT?TAT? Who will be doing the testing?Who will be doing the testing? What about positives?What about positives? PTPT
RHIVW (CAP)RHIVW (CAP)
Provider Performed Microscopy
Things to think about…Things to think about… Training and continued proficiencyTraining and continued proficiency PicturesPictures Use of “live” specimensUse of “live” specimens MicroscopeMicroscope
Conclusions
Decide first if test needs to be done at Decide first if test needs to be done at point of carepoint of care
Pick the right testPick the right test Keep in mind the manual nature of the Keep in mind the manual nature of the
testingtesting