A broad-range PCR technique for the diagnosis of infective endocarditis

Infective endocarditis (IE) remains a severe and potentially fatal disease demanding sophisticated diagnostic strategies for detection of the causative microorganisms. The aim of the present study was to develop a broad-range 16S ribosomal RNA gene polymerase chain reaction in the routine diagnostic of IE for the early diagnosis of fatal disease. A broad-range PCR technique was selected and evaluated in terms of its efficiency in the diagnosis of endocarditis using 19 heart valves from patients undergoing cardiovascular surgeries at the Habib Bourguiba Hospital of Sfax, Tunisia, on the grounds of suspected IE. The results demonstrated the efficiency of this technique particularly in cases involving a limited number of bacteria since it helped to increase detection sensitivity. The technique proved to be efficient, particularly, in the bacteriological diagnosis of IE in contexts involving negative results from conventional culture methods and other contexts involving bacterial species that were not amenable to identification by phenotypic investigations. Indeed, the sequencing of the partial 16S ribosomal RNA gene revealed the presence of Bartonella henselae, Enterobacter sp., and Streptococcus pyogenes in three heart valves with the negative culture. It should be noted that the results obtained from the polymerase chain reaction-sequencing identification applied to the heart valve and the strain isolated from the same tissue were not consistent with the ones found by the conventional microbiological methods in the case of IE caused by Gemella morbillorum. In fact, the results from the molecular identification revealed the presence of Lactobacillus jensenii. Overall, the results have revealed that the proposed method is sensitive, reliable and might open promising opportunities for the early diagnosis of IE.