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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.

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Presentation on theme: "Point of Care Testing and Microbiology Yvette S. McCarter, PhD, DABMM Director, Clinical Microbiology Laboratory University of Florida Health Science Center-Jacksonville."— Presentation transcript:

1 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

2 Point of Care Testing and Microbiology Objectives Historical Perspective Historical Perspective POCT – Clinically-relevant? Cost- effective? POCT – Clinically-relevant? Cost- effective? Currently available Microbiology POCT Currently available Microbiology POCT Advantages and disadvantages of Microbiology POCT Advantages and disadvantages of Microbiology POCT

3 Point of Care Testing Historical Perspective Clinical Ward Laboratory Testing Centralized Laboratory Testing Point of Care Testing

4 Test Life Cycle Centralized Lab Test ordered Test ordered Test request processed Test request processed Specimen obtained Specimen obtained Specimen transported to lab Specimen transported to lab Specimen processed by lab Specimen processed by lab Specimen analyzed Specimen analyzed Results reviewed by lab staff Results reviewed by lab staff Results reported to clinician Results reported to clinician Clinician acts on results Clinician acts on results Point of Care Test ordered Specimen obtained Specimen analyzed Clinician acts on result

5 Why is Point of Care testing a clinically relevant alternative to centralized testing? Decreased Turnaround Time

6 Why decreased turnaround time? Elimination of specimen transport and processing time

7 Transport/Processing Time vs. Analysis Time Salem et al. JAMA 1991; 266:

8 Clinical Benefits of Decreased Turnaround Time Evidence-based medical decisions in real time Evidence-based medical decisions in real time Eliminates need for ordering additional, unnecessary tests Eliminates need for ordering additional, unnecessary tests Reduction in unneeded medications Reduction in unneeded medications Decrease in physician switching Decrease in physician switching Perceived patient benefits Perceived patient benefits

9 Economic Considerations COST!!!! Look beyond cost per test Look beyond cost per test Judge cost-effectiveness in the context of total cost of patient care Judge cost-effectiveness in the context of total cost of patient care

10 Why is Point of Care testing a cost- effective alternative to centralized testing? Decreased Turnaround Time

11 Economic Benefits of Decreased Turnaround Time Reduction in duplicate test orders Reduction in duplicate test orders Reduced consumption of other expensive services/products (lab tests, pharmaceuticals) Reduced consumption of other expensive services/products (lab tests, pharmaceuticals) Decreased length of stay Decreased length of stay

12 Economic Benefits of Decreased Turnaround Time Point of Care Testing in the Post Anesthesia Care Unit Use of POCT resulted in: Use of POCT resulted in: reduced test TAT from 26 min to 2 min reduced test TAT from 26 min to 2 min decreased length of stay by 18 min decreased length of stay by 18 min documented cost savings due to decreased length of stay documented cost savings due to decreased length of stay Goodwin MLO 1994; 26 (9S):15-18.

13 Microbiology Point of Care Testing

14 Your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. -Dr. Ian Malcolm Jurassic Park

15 Why do we need it? Evidence-based medical decisions in real time Evidence-based medical decisions in real time Eliminates need for ordering additional, unnecessary tests Eliminates need for ordering additional, unnecessary tests Reduction in unneeded medications Reduction in unneeded medications Perceived patient benefits Perceived patient benefits Reduction in duplicate test orders Reduction in duplicate test orders Reduced consumption of other expensive services/products (lab tests, pharmaceuticals) Reduced consumption of other expensive services/products (lab tests, pharmaceuticals)

16 What to consider… Choose the appropriate test Choose the appropriate test Difficulty? Difficulty? Necessary skill level? Necessary skill level? How much QC? How much QC? Training Training See one, do one, teach one See one, do one, teach one Procedure Procedure Dont assume Dont assume Pictures Pictures

17 Microbiology Point of Care Testing Most common Group A streptococcal pharyngitis Group A streptococcal pharyngitis Helicobacter pylori antibody Helicobacter pylori antibody Helicobacter pylori Helicobacter pylori HIV antibody HIV antibody Provider Performed Microscopy Provider Performed Microscopy Skin KOH Skin KOH Vaginal KOH Vaginal KOH Vaginal wet preps Vaginal wet preps

18 Microbiology Point of Care Testing Additional testing available Influenza A, B and A/B Influenza A, B and A/B Infectious mononucleosis Infectious mononucleosis Lyme antibody Lyme antibody Respiratory syncytial virus Respiratory syncytial virus Pinworm preps Pinworm preps Gram stain Gram stain

19 Group A Streptococcal Pharyngitis Acute pharyngitis=most frequent reason for pediatrician and PCP visits Acute pharyngitis=most frequent reason for pediatrician and PCP visits Most pharyngitis viral in origin Most pharyngitis viral in origin Group A strep 15% of pharyngitis cases in children Group A strep 15% of pharyngitis cases in children Difficult to distinguish streptococcal and non-streptococcal disease Difficult to distinguish streptococcal and non-streptococcal disease

20 Group A Streptococcal Pharyngitis

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22 Early recognition and treatment important Early recognition and treatment important Shorten duration of clinical illness Shorten duration of clinical illness Prevent transmission Prevent transmission Prevent sequelae Prevent sequelae Rheumatic heart disease Rheumatic heart disease Glomerulonephritis Glomerulonephritis

23 Group A Streptococcal Pharyngitis - Diagnosis Culture Culture Gold standard Gold standard hr result hr result Rapid antigen tests Rapid antigen tests Enzyme immunoassays (POCT) Enzyme immunoassays (POCT) Optical immunoassays Optical immunoassays Nucleic acid based tests Nucleic acid based tests

24 Group A Streptococcal Pharyngitis - POCT Pediatric Setting Evaluated 2401 patients with suspected streptococcal pharyngitis with rapid latex test and culture Evaluated 2401 patients with suspected streptococcal pharyngitis with rapid latex test and culture Conclusions Conclusions Rapid test available while patient on-site Rapid test available while patient on-site Same day Rx in 90% of patients Same day Rx in 90% of patients Wiedermann et al. J Am Board Fam Pract 1991; 4:79-82

25 Group A Streptococcal Pharyngitis - POCT Emergency Department Compared clinical judgment vs. rapid testing for diagnosis of pharyngitis in 147 patients Compared clinical judgment vs. rapid testing for diagnosis of pharyngitis in 147 patients Conclusions Conclusions Rapid test significantly better than clinical judgment for determining disease Rapid test significantly better than clinical judgment for determining disease Rapid test eliminates problems/costs of empiric Rx and patient follow-up compliance Rapid test eliminates problems/costs of empiric Rx and patient follow-up compliance Only 14% of patients followed up on cultures Only 14% of patients followed up on cultures DuBois et al. Ann Emerg Med 1986; 15:

26 Group A Streptococcal Pharyngitis - POCT Primary Care Setting Studied impact of rapid test on physician prescribing patterns Studied impact of rapid test on physician prescribing patterns Conclusions Conclusions Antibiotic prescribing patterns changed when rapid test used Antibiotic prescribing patterns changed when rapid test used Physicians initiated Rx with positive result and waited for culture before initiating Rx with negative result Physicians initiated Rx with positive result and waited for culture before initiating Rx with negative 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:

27 Group A Streptococcal Pharyngitis - POCT 37 CLIA waived tests 37 CLIA waived tests Abbott Signify Abbott Signify Biostar Acceava Biostar Acceava Binax NOW Binax NOW Quidel QuickVue Quidel QuickVue BD LINK BD LINK Meridian ImmunoCard Meridian ImmunoCard

28 Group A Streptococcal Pharyngitis - POCT Advantages Advantages Results in 5 min Results in 5 min Internal controls Internal controls Clear endpoints Clear endpoints Disadvantages Sensitivities lower than company claims

29 Group A Streptococcal Pharyngitis - POCT Things to remember… Things to remember… Verification of test against culture Verification of test against culture Culture all negative tests Culture all negative tests Rapid test collection swab often different from culture swab Rapid test collection swab often different from culture swab

30 Helicobacter pylori Infection Early 1980s link between H. pylori and peptic ulcer disease/gastric cancer established Early 1980s link between H. pylori and peptic ulcer disease/gastric cancer established Epidemiology Epidemiology Up to 50% of worlds population infected Up to 50% of worlds population infected Fecal-oral and oral-oral spread Fecal-oral and oral-oral spread Prevalence of infection increases with age (developed countries) Prevalence of infection increases with age (developed countries)

31 Helicobacter pylori Infection Pathology Pathology Lives under protective mucous layer Lives under protective mucous layer Acute gastritis chronic active gastritis Acute gastritis chronic active gastritis Duodenal ulcer Duodenal ulcer MALT lymphoma MALT lymphoma Gastric ulcer Gastric ulcer Gastric carcinoma Gastric carcinoma

32 Helicobacter pylori Infection

33 Helicobacter pylori Diagnostic Methods Noninvasive Noninvasive Antibody detection Antibody detection IgG (POCT) IgG (POCT) IgA IgA Urea breath test Urea breath test Stool antigen Stool antigen

34 Helicobacter pylori Diagnostic Methods Invasive Invasive Biopsy (multiple required) Biopsy (multiple required) Histopathology Histopathology Silver or Warthin-Starry stainsSilver or Warthin-Starry stains Rapid urease testing (POCT) Rapid urease testing (POCT) Agar based gel or paper stripAgar based gel or paper strip Culture Culture

35 Helicobacter pylori POCT Biopsy Biopsy 7 CLIA waived tests 7 CLIA waived tests Serim PyloriTek Serim PyloriTek CLOtest CLOtest Chek-Med Systems HP One Chek-Med Systems HP One Serology Serology 18 CLIA waived tests 18 CLIA waived tests Meridian ImmunoCard STAT Meridian ImmunoCard STAT Abbott Signify Abbott Signify Quidel QuickVue Quidel QuickVue

36 Helicobacter pylori POCT

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38 Advantages Advantages Rapid results Rapid results 15 min-24 hr 15 min-24 hr Internal controls Internal controls Room temperature storage and incubation Room temperature storage and incubation Disadvantages Potential for false negatives Rapid Urease Testing

39 Helicobacter pylori POCT Advantages Advantages Rapid results Rapid results 5 min 5 min Built in controls Built in controls External controls External controls Room temperature storage Room temperature storage Disadvantages Whole blood less sensitive than serum Antibody Detection

40 HIV Infection The Virus Retrovirus Retrovirus Bar-shaped core Bar-shaped core 2 short strands of RNA 2 short strands of RNA Enzymes Enzymes Reverse transcriptase Reverse transcriptase Protease Protease Ribonuclease Ribonuclease Integrase Integrase Outer lipid envelope containing an antigen (gp160) that helps virus bind to CD4 cells Outer lipid envelope containing an antigen (gp160) that helps virus bind to CD4 cells

41 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

42 Diagnosis of HIV Culture Culture Rarely performed Rarely performed Serology - Gold Standard Serology - Gold Standard Sensitive EIA Sensitive EIA Confirmatory Western blot Confirmatory Western blot Window period Window period P24 antigen P24 antigen PCR PCR

43 Diagnosis of HIV Alternative Fluids and Home Collection Alternative Fluids and Home Collection OraSure OraSure Oral mucosal transudate - serum derived fluid, enters saliva from gingival crevices, contains antibody Oral mucosal transudate - serum derived fluid, enters saliva from gingival crevices, contains antibody Can be used for EIA and Western blot testing, comparable sensitivity to serumCan be used for EIA and Western blot testing, comparable sensitivity to serum Calypte (Sentinel) Calypte (Sentinel) Urine Urine 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 Access Home Access Finger stick, mail in blood spot for testing Finger stick, mail in blood spot for testing Pre and post test counseling Pre and post test counseling Problem with improperly collected specimens Problem with improperly collected specimens

44 Diagnosis of HIV - POCT 1 CLIA waived test 1 CLIA waived test OraQuick Rapid HIV-1 Antibody Test OraQuick Rapid HIV-1 Antibody Test

45 Diagnosis of HIV - POCT Public Health Setting Evaluated 1923 samples from STD clinics and HIV counseling centers using SUDS and conventional EIA / WB Evaluated 1923 samples from STD clinics and HIV counseling centers using SUDS and conventional EIA / WB Conclusions Conclusions SUDS sensitivity 100%, PPV 88% (STD), PPV 81% (HIV) SUDS sensitivity 100%, PPV 88% (STD), PPV 81% (HIV) Rapid testing feasible in public health settings (accurate, reasonable cost, results during visit) Rapid testing feasible in public health settings (accurate, reasonable cost, results during visit) Kassler et al. J Clin Microbiol 1995: 33:

46 Diagnosis of HIV - POCT Labor and Delivery Labor and Delivery Evaluated 380 women presenting with unknown HIV status Evaluated 380 women presenting with unknown HIV status Compared OraQuick performed in L&D and lab Compared OraQuick performed in L&D and lab Conclusions Conclusions Median TAT POCT=45 min, lab=3.5 hr Median TAT POCT=45 min, lab=3.5 hr More rapid implementation of antiviral Rx with POCT More rapid implementation of antiviral Rx with POCT MMWR 2003; 52:

47 Diagnosis of HIV - POCT Appropriate settings Appropriate settings Evaluation of needlestick exposures Evaluation of needlestick exposures Labor and Delivery Labor and Delivery Previously untested for HIV Previously untested for HIV Public Health Public Health STD clinics STD clinics HIV counseling centers HIV counseling centers ED ED

48 Diagnosis of HIV - POCT Advantages Advantages Rapid results Rapid results Counseling Counseling Rx Rx Internal controls Internal controls Accurate Accurate Disadvantages Must confirm positive results Restrictions

49 Diagnosis of HIV - POCT Restrictions Sale restricted to clinical laboratories Sale restricted to clinical laboratories that have an adequate QA program; and that have an adequate QA program; and where there is assurance operators will receive and use instructional materials where there is assurance operators will receive and use instructional materials Approved only for use by an agent of a clinical laboratory Approved only for use by an agent of a clinical laboratory Test subjects must receive Subject Information prior to collection and appropriate information when results are provided Test subjects must receive Subject Information prior to collection and appropriate information when results are provided Not approved to screen blood or tissue donors Not approved to screen blood or tissue donors

50 Diagnosis of HIV - POCT Things to think about… Things to think about… Can a central lab give you adequate TAT? Can a central lab give you adequate TAT? Who will be doing the testing? Who will be doing the testing? What about positives? What about positives? PT PT RHIVW (CAP) RHIVW (CAP)

51 Provider Performed Microscopy Things to think about… Things to think about… Training and continued proficiency Training and continued proficiency Pictures Pictures Use of live specimens Use of live specimens Microscope Microscope

52 Conclusions Decide first if test needs to be done at point of care Decide first if test needs to be done at point of care Pick the right test Pick the right test Keep in mind the manual nature of the testing Keep in mind the manual nature of the testing


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