Performance of PCR on adenopathies for the detection of fastidious pathogens

Abstract number: P1831

Jaton-Ogay K., Greub G., André C., Bille J.

Objectives: Molecular tools have proven to be extremely useful in the clinical diagnostic laboratory, especially for detecting difficult to grow microorganisms. Although technical issues such as reproducibility, sensitivity, and specificity of these tests are important, costs and potential contribution to patient care are also of concern and need to be addressed. Here, we assessed the performance of PCR on adenopathies, for the detection of fastidious bacteria, which frequently remain undetected as they grow poorly or not at all on conventional culture media.

Methods: A total of 377 samples (322 fresh biopsies and 55 paraffin-embedded adenopathies) were investigated by 3 different PCR in our molecular diagnostic laboratory between 2000 and 2008. These PCR included 2 in house real-time TaqMan PCR specific for Bartonella henselae and Mycobacterium tuberculosis.) and a bacterial broad-range PCR with classic amplification of the 16S rDNA followed by sequencing of the amplified product.

Results: On the 377 samples, 483 PCR tests were performed. Ninety-two samples (73 fresh biopsies and 19 paraffin-embedded) were positive for one of the PCR corresponding to 24% (23% and 35% respectively) of the samples. Only one sample contained inhibitors. As many as 34% of the paraffin-embedded samples gave a positive result for M. tuberculosis complex (see Table).

For the bacterial broad-range PCR, 2/23 (1 Rothia mucilaginosa, 1 Pseudomonas spp.) were positive both in freshly biopsied specimens.

Conclusion: Assessing the performance of molecular diagnosis on clinical management will be the future challenge for molecular diagnosis. These data will help to better focus the indications for molecular tests. Here for 24% of the adenopathies tested, a fastidious pathogen has been detected and identified by specific PCR or bacterial broad-range PCR. Nevertheless more studies with economical and clinical impacts are needed.

 All (n = 377)All positive (n = 92)% of +Positive for B. henselae/total no. of samples tested% of +Positive for M. tuberculosis/total no. of samples tested% of +
Freshly biopsied3227323%11/10810%60/24824%

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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