Pneumocystis jiroveci Assay Evaluated in Multicenter Trial

A Real Time polymerase chain reaction (PCR) assay of Pneumocystis jiroveci was validated in a multicenter trial.

MycAssayPneumocystis is a commercial assay that targets the P. jirovecii mitochondrial large subunit.

Myconostica (Manchester, United Kingdom), a company specializing in rapid molecular diagnostic tests for life-threatening fungal infections, announced the results of the prospective trial of its CE marked kit, MycAssay Pneumocystis. The trial results compared well with clinical diagnosis using nonmolecular methods and demonstrated the high sensitivity and specificity of the PCR diagnostic assay.

The multicenter trial recruited 110 subjects from a variety of underlying diseases and conditions including solid organ transplants, leukemia, solid tumors, and HIV. Respiratory bronchoalveolar samples were analyzed and 13/14 patients with clinically proven Pneumocystis pneumonia (PCP) were identified and 9/96 patients without PCP at the time of the test also gave positive results. Subsequently one of these patients developed PCP while the others were considered to be colonized with P. jirovecii.

PCP is a very dangerous infection in both AIDS and non-AIDS patients with mortality rates in excess of 20%.Currently, establishing the diagnosis of PCP is performed by microscopy of lung tissue, bronchial lavage, or other deep respiratory samples. PCP primarily affects the alveoli; consequently, deep pulmonary samples are necessary for adequate microscopy. However, microscopic diagnosis, including the Merifluor-Pneumocystis direct fluorescent antigen (MP-DFA) test, has limitations. For example, a much lower number of organisms are usually present in non-AIDS patients with PCP, which makes the microscopic tests more difficult to perform and lees reliable.

Commenting on these results, Dr. John Thornback, Chief Business Officer of Myconostica commented, "This is, to our knowledge, the first multicenter prospective trial of a commercial PCR test for Pneumocystis. Pneumocystis PCR is clearly a very sensitive means of detecting this fungal pathogen in at risk patients. The introduction of new technologies such as Pneumocystis PCR often results in reappraisal of disease, and this may be the case here. The early identification of infected patients may open opportunities for early interventions. Myconostica is committed to working with the clinical community to better understand the role that PCR can play in the diagnosis of life threatening fungal infections, such as Pneumocystis, as early as possible in at risk patient populations."

The results of the trial were published, ahead of print, in the March 2, 2011, Journal of Clinical Microbiology.

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