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
POCT – Clinically-relevant? Cost-
effective?
Currently available 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 request processed
Specimen obtained
Specimen transported to lab
Specimen processed by lab
Specimen analyzed
Results reviewed by lab staff
Results reported to clinician
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
7. Transport/Processing Time vs.
Analysis Time
0
5
10
15
20
25
30
35
40
Blood
Gases
K+/Na+ Hematocrit
TAT
(min)
Analysis Time
Transport/Processing Time
Salem et al. JAMA 1991; 266:382-389
8. Clinical Benefits of Decreased
Turnaround Time
Evidence-based medical decisions in
“real time”
Eliminates need for ordering additional,
unnecessary tests
Reduction in unneeded medications
Decrease in physician “switching”
Perceived patient benefits
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
Reduced consumption of other
expensive services/products (lab tests,
pharmaceuticals)
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:
reduced test TAT from 26 min to 2
min
decreased length of stay by 18 min
documented cost savings due to
decreased length of stay
Goodwin MLO 1994; 26 (9S):15-18.
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”
Eliminates need for ordering additional,
unnecessary tests
Reduction in unneeded medications
“Perceived” patient benefits
Reduction in duplicate test orders
Reduced consumption of other expensive
services/products (lab tests, pharmaceuticals)
16. What to consider…
Choose the appropriate test
Difficulty?
Necessary skill level?
How much QC?
Training
See one, do one, teach one
Procedure
Don’t assume
Pictures
17. Microbiology Point of Care
Testing
Most common
Group A streptococcal pharyngitis
Helicobacter pylori antibody
Helicobacter pylori
HIV antibody
Provider Performed Microscopy
Skin KOH
Vaginal KOH
Vaginal wet preps
18. Microbiology Point of Care
Testing
Additional testing available
Influenza A, B and A/B
Infectious mononucleosis
Lyme antibody
Respiratory syncytial virus
Pinworm preps
Gram stain
19. Group A Streptococcal
Pharyngitis
Acute pharyngitis=most frequent reason
for pediatrician and PCP visits
Most pharyngitis viral in origin
Group A strep 15% of pharyngitis
cases in children
Difficult to distinguish streptococcal and
non-streptococcal disease
22. Group A Streptococcal
Pharyngitis
Early recognition and treatment important
Shorten duration of clinical illness
Prevent transmission
Prevent sequelae
Rheumatic heart disease
Glomerulonephritis
23. Group A Streptococcal
Pharyngitis - Diagnosis
Culture
Gold standard
24-48 hr result
Rapid antigen tests
Enzyme immunoassays (POCT)
Optical immunoassays
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
Conclusions
Rapid test available while patient
on-site
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
Conclusions
Rapid test significantly better than clinical
judgment for determining disease
Rapid test eliminates problems/costs of empiric
Rx and patient follow-up compliance
Only 14% of patients followed up on cultures
DuBois et al. Ann Emerg Med 1986; 15:157-159
26. Group A Streptococcal
Pharyngitis - POCT
Primary Care Setting
Studied impact of rapid test on physician
prescribing patterns
Conclusions
Antibiotic prescribing patterns changed when
rapid test used
Physicians initiated Rx with positive result and
waited for culture before initiating Rx with
negative result
• Reduced inappropriate antibiotic usage
• Reduced unnecessary cost and antibiotic
exposure
True et al. J Fam Prac 1986; 23:215-219
27. Group A Streptococcal
Pharyngitis - POCT
37 CLIA “waived”
tests
Abbott Signify
Biostar Acceava
Binax NOW
Quidel QuickVue
BD LINK
Meridian
ImmunoCard
28. Group A Streptococcal
Pharyngitis - POCT
Advantages
Results in 5 min
Internal controls
Clear endpoints
Disadvantages
Sensitivities lower
than company
claims
29. Group A Streptococcal
Pharyngitis - POCT
Things to remember…
Verification of test against culture
Culture all negative tests
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
Epidemiology
Up to 50% of world’s population infected
Fecal-oral and oral-oral spread
Prevalence of infection increases with age
(developed countries)
39. Helicobacter pylori
POCT
Advantages
Rapid results
5 min
Built in controls
External controls
Room
temperature
storage
Disadvantages
Whole blood less
sensitive than
serum
Antibody Detection
40. HIV Infection
The Virus
Retrovirus
Bar-shaped core
2 short strands of RNA
Enzymes
Reverse transcriptase
Protease
Ribonuclease
Integrase
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
Rarely performed
Serology - Gold Standard
Sensitive EIA
Confirmatory Western blot
Window period
P24 antigen
PCR
43. Diagnosis of HIV
Alternative Fluids and Home Collection
OraSure
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 serum
Calypte (Sentinel)
Urine
• Lower sensitivity and specificity than serum for
diagnosis
• No FDA licensed Western blot
Home Access
Finger stick, mail in blood spot for testing
Pre and post test counseling
Problem with improperly collected specimens
44. Diagnosis of HIV - POCT
1 CLIA “waived” 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
Conclusions
SUDS sensitivity 100%, PPV 88% (STD), PPV
81% (HIV)
Rapid testing feasible in public health settings
(accurate, reasonable cost, results during visit)
Kassler et al. J Clin Microbiol 1995: 33:2899-2902
46. Diagnosis of HIV - POCT
Labor and Delivery
Evaluated 380 women presenting with
unknown HIV status
Compared OraQuick performed in L&D
and lab
Conclusions
Median TAT POCT=45 min, lab=3.5 hr
More rapid implementation of antiviral
Rx with POCT
MMWR 2003; 52:866-868
47. Diagnosis of HIV - POCT
Appropriate settings
Evaluation of needlestick exposures
Labor and Delivery
Previously untested for HIV
Public Health
STD clinics
HIV counseling centers
ED
48. Diagnosis of HIV - POCT
Advantages
Rapid results
Counseling
Rx
Internal controls
Accurate
Disadvantages
Must confirm
positive results
“Restrictions”
49. Diagnosis of HIV - POCT
Restrictions
Sale restricted to clinical laboratories
that have an adequate QA program; and
where there is assurance operators will receive and
use instructional materials
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
Not approved to screen blood or tissue donors
50. Diagnosis of HIV - POCT
Things to think about…
Can a central lab give you adequate
TAT?
Who will be doing the testing?
What about positives?
PT
RHIVW (CAP)
