SeptiFast for the investigation of bacterial and fungal DNA in sterile fluids

Abstract number: P1970

Alvarez M., Parra J., Peña A., Carlos S., Chueca N., Torres M., Pérez-López J.A., Piedrola G., Maroto M.C., García F.

Objective: to investigate the diagnostic performance of a novel molecular tests for the diagnosis of pathogenic bacteria and fungi (SeptiFast, Roche Diagnostics) in sterile fluids coming from joints, pleura and peritoneum, and to compare molecular findings with conventional culture microbiological methods.

Patients and Methods: 50 samples from 44 patients were included in the study. Samples corresponded to synovial fluid (n = 17), pleural fluid (n = 15), ascytic fluid (n = 9), peritoneal fluid (n = 3), and 6 samples were bone/tissue/prosthesis samples from prosthetic joint infection. All the samples were studied using the LightCycler® SeptiFast Test MGRADE (Roche Diagnostics), a multiplex real time PCR that in six hours investigates Gram-positive, Gram-negative, and species of Aspergillus and Candida; in parallel, standard microbiological procedures run in our laboratory were applied to all the samples.

Results: overall, 30% of the samples were positive using Septifast and 14% using conventional culture. Bacterial DNA from Coagulase Negative Staphilococci (n = 5), Staphylococcus aureus (n = 4), Streptococcus spp. (n = 2), Streptococcus pneumoniae, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Escherichia coli. Two of the Staphylococcus aureus detected with Septifast were also isolated by convencional methods. Culture positive/Septifast negative results were present in 5 samples (Staphylococcus aureus, Peptostreptococcus anaerobius, Streptococcus viridans, Streptococcus agalactiae and Streptococcus pneumoniae).

A subanalysis taking into account the type of sample investigated revealed that 66.6% of the joint infection related samples were positive by both methods (2 Septifast/Culture positive and 2 Septifast negative/Culture positive), 55.5% of the ascytic fluids (4 Septifast positive/culture negative and 1 Septifast negative/culture positive), 46.6% of the pleural fluids (5 Septifast positive/culture negative and 2 Septifast negative/culture positive). All synovial fluids were culture negative, and two (11.8%) were positive by Septifast.

Conclusion: Using Septifast, DNA from the panel of bacteria investigated could be detected in a large number of negative culture samples. However, the finding of samples with a positive conventional culture result and a negative Septifast test sets the rationale, if possible, for the use of both tests for the diagnostic microbiology of these samples.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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