Available February 1, 2014
MEDLAB introduces Molecular Clostridium difficile test
MEDLAB is proud to introduce a cutting edge DNA based C diff test, with outstanding sensitivity and specificity,
that does not require confirmation testing. This translates into superior positive and negative predictive value for
toxigenic Clostridium difficile bacterial DNA with a 1-2 day turn-around-time.
C. difficile infections are a major problem among recently hospitalized patients and those living in long term care
facilities. The infections are the most common cause of healthcare-associated diarrhea in adults and can often lead
to dehydration or electrolyte imbalance or even death. Furthermore, it has been widely reported that C diff
infections are becoming increasingly virulent and less responsive to metronidazole therapy, resulting in rising
incidence and worse outcomesi. Since the infection can range in severity from asymptomatic to life-threatening,
rapid and accurate diagnosis is critical for treatment decisions and infection control intervention. Relapses are also
common in 20% to 60% of the cases, often leading to rehospitalizations ii,iii.
The new Guidelines for Diagnosis, Treatment and Prevention of Clostridium difficile published in 2013 by
American Journal of Gastroenterology recommends first-line molecular DNA testing for diagnosis of the disease iv.
This new test conforms to this recommendation. In addition, it detects BOTH Toxigenic A and B strains of C diff.
Comparison of the current test with the new test is shown below and clearly demonstrates why the
current test will be discontinued effective March 1, 2014.
Test
Code
205300
205303
Test Methodology
GDH EIAv (current test)
DNA Molecularvi
Sensitivity
39.7%
98.6%
Specificity
97.7%
99.1%
Positive
Predictive
Value
74.0%
95.9%
Negative
Predictive
Value
90.5%
99.7%
Reflex
Confirmation
Required
Not Required
Specimen is loose stool (formed stools will be rejected) and should be in a sterile, labeled cup and kept at 2-8
degrees C, and is stable for up to 7 days. Turn-around-time is 24hrs from receipt at the MEDLAB laboratory.
The DNA Molecular test is FDA cleared and payable by both Medicare and Medicaid. Retesting of previous C diff
negative patients can be useful after 7 days, when still presenting with clinically significant symptoms .
Bottom-line: Switching testing from traditional EIA to amplified DNA leads to:






Significant decrease in patient isolation days
Decrease in number of tests ordered
Decrease in metronidazole treatment for patients with negative C diff tests
Decrease in hospital readmissions
Decrease in care providers time caring for isolated patients
Increase in patient satisfaction
SEE FOLLOWING PAGE FOR TEST ORDERING SPECIFICS
Effective February 1, 2014 MEDLAB will introduce a new Molecular C. diff test
TEST NAME:
C diff Amplified DNA test
NEW TEST CODE:
205303
AVAILABLE:
February 1, 2014
SPECIMEN:
Loose Stool – Two Patient Identifiers Necessary (Any formed stools will be rejected)
SAMPLE STABILITY:
7 days, Refrigerated (4 degrees C)
TURN-AROUND-TIME: 24-48 hours
SENSITIVITY:
98.6% (New Test) vs 39.7% (Old Test)
SPECIFICITY:
99.1% (New Test) vs 97.7% (Old Test)
FDA STATUS:
FDA cleared
REIMBURSEMENT:
Medicare/Medicaid Reimbursable
COMPLIANCE:
Complies with 2013 Guidelines for Diagnosis, Treatment, and Prevention of Clostridium
difficile Infections (J Gastroenterology, 108:478, April 2013) (available by request from
MEDLAB Account Managers)
eMEDLAB:
Orderable in eMEDLAB effective February 1, 2014
NOTE:
Old C diff test (GDH EIA) will be discontinued on March 1, 2013. Any unspecified C
diff Orders will be tested utilizing the new DNA based technology with superior
sensitivity and specificity.
For any further questions or concerns please contact your account manager or our client solutions
department at 1-800-522-7556.
i
Peterson, L. R. et al. Laboratory Testing for Clostridium difficile Infection, Light at the End of the Tunnel. Microbiology and
Infectious Disease, Am J Clin Pathol (2011) 136:372-380.
ii
Ryan, K. J., Ray, C. G. (editors) Sherris Medical Microbiology (4th edition) McGraw Hill. Pp. 322-324.
iii
Kelly, C.P., LaMont, J.T., Clostridium difficile—more difficult than ever. N Eng J Medicine, Oct (2008) 18:1932-1940.
iv
Surawicz C.M. et al., Guidelines for diagnosis, treatment, and prevention of Clostridium difficile infections. Am J Gastroenterol.
(2013) 108:478-498.
v
Peterson, L. R. et al. Laboratory Testing for Clostridium difficile Infection, Light at the End of the Tunnel. Microbiology and
Infectious Disease, Am J Clin Pathol (2011) 136:372-380.
vi
Quidel Molecular FDA submission data following discordant resolution. (2013).