High Correlation between Molecular Sequencing and Histopathological Examination of Parallel Samples in Culture-Negative Endocarditis
Angela MB Collie, Nabin K Shrestha, Geraldine S Hall, E Rene Rodriguez, Carmela D Tan. Cleveland Clinic, Cleveland, OH
Background: Microbiological cultures of blood and excised valves are often negative in patients undergoing surgical interventions. Thus, molecular sequencing of cardiac valve specimens is increasingly used to identify the specific organism(s) involved in culture-negative endocarditis. The present study examines molecular sequencing and histopathological results on parallel cardiac valve specimens and identifies histopathologic features common to positive specimens.
Design: All cardiac valve specimens with molecular PCR sequencing results were identified at our institution. For cases where a surgical specimen was available, the histologic features of acute inflammation, necrosis, chronic inflammation, granulation tissue, and fibrinous vegetations were analyzed. Organisms were identified with special stains including Gram, Gomori methenamine silver, and periodic acid-Schiff. PCR sequencing results, including bacterial 16S rRNA, acid fast bacterial heat shock protein 65, and fungal 28S rRNA, were obtained. Molecular results and histopathologic characteristics were compared.
Results: One hundred eleven cardiac valves from 100 patients had PCR results and histologic examination of a parallel surgical specimen. Seventy eight valves (70%) had agreement in the presence or absence of organisms in both studies (Table 1). Three valves (3%) had organisms identified histologically that were not identified by PCR. Thirty valves (27%) did not have an organism identified histologically but did have an organism identified by PCR. When organisms were not identified histologically, acute inflammation was more common in valves with positive PCR (50%) compared with negative PCR (25%) (p<0.001), and fibrinous vegetations were more common in valves with positive PCR (23%) compared with negative PCR (9%) (p<0.01). Necrosis was only observed in PCR positive cases.
|Histological examination (diagnosis)||PCR positive||PCR negative|
|Organisms not identified||30||34|