[Infective Endocarditis with Unknown Etiology: Possibilities of Conquering and Role of Microbiologistics]

[Clinical and diagnostic value of including PCR blood test in the traditional algorithm for identifying causative agents of infective endocarditis: a cohort study of 124 patients]

BACKGROUND

If infective endocarditis (IE) is suspected, the determination of the etiology is of fundamental importance for the verification of the disease and the appointment of effective therapy. Microbiological diagnostic features are important, but they often need to be supplemented by culture-independent studies of pathological agents.

AIM

To investigate of the diagnostic advantage and value of quantitative analysis of molecular biological methods (polymerase chain reaction - PCR, sequencing) in addition to microbiological examination of whole venous blood in IE.

MATERIALS AND METHODS

We examined 124 patients with suspected or significant IE (DUKE 2015) hospitalized in the Vinogradov City Clinical Hospital (2015-2021). All patients underwent parallel microbiological (cultural) and molecular biological (PCR or PCR followed by sequencing) examination of venous whole blood samples.

RESULTS

The introduction of an early parallel PCR study into the algorithm for the etiological diagnosis of IE made it possible to obtain an additional advantage in 43/124 (34.7%) patients, which made it possible to exclude unreliable results in the determination of CoNS skin commensals and pathogens atypical for IE or contamination and identify the true pathogens, and also for the first time to isolate the etiopathogenetic pathogen with a negative microbiological study. It was shown that in IE associated with CoNS, the association with the disease was confirmed by PCR in 21.4% (3/14) and refuted in 71.4% (10/14). The coincidence of the results of microbiological and PCR studies of blood samples was obtained only in 35/95 (36.8%). Positive results of PCR analysis of blood of biological material with negative results of culture were obtained in 22/51 (43.1%), of which 2/22 (9.0%) were able to confirm the presence of Bartonella spp DNA. The presented complex algorithm made it possible to significantly increase the possibility of intravital identification of the pathogen in the blood from 58.9 to 76.6%. IE with unknown etiology was present in 29/124 (23.4%) patients. A parallel PCR study allowed timely correction of antibiotic therapy in 43/124 (34.7%) patients.

CONCLUSION

Expansion of indications for the use of PCR studies, primarily whole venous blood samples, is justified, not only in IE with negative results of microbiological examination, but also as a control method for the reliability of the results of traditional (cultural) diagnostic methods.

[Global and national trends in the evolution of infective endocarditis]

For the recent 20 years, substantial changes have occurred in all aspects of infectious endocarditis (IE), the evolution of risk factors, modernization of diagnostic methods, therapeutic and preventive approaches. The global trends are characterized by increased IE morbidity among people older than 65 who use intravenous psychoactive drugs. The epidemiological trend is represented by reduced roles of chronic rheumatic heart disease and congenital heart defects, increased proportion of IE associated with medical care, valve replacement, installation of intracardiac devices, and increased contribution of Staphylococcus spp. and Enterococcus spp. to the IE etiology. Additional visualization methods (fluorodeoxyglucose positron emission tomography with 18F-fludesoxyglucose (18F-FDG PET-CT), labeled white blood cell single-photon emission computed tomography (SPECT), and modernization of the etiological diagnostic algorithm for determining the true pathogen (immunochemistry, polymerase chain reaction, sequencing) also become increasingly important. The COVID-19 pandemic has also adversely contributed to the IE epidemiology. New prospects of treatment have emerged, such as bacteriophages, lysins, oral antibacterial therapy, minimally invasive surgical strategies (percutaneous mechanical aspiration), endovascular mechanical embolectomy. The physicians' compliance with clinical guidelines (CG) is low, which contributes to the high rate of adverse outcomes of IE, while simple adherence to the CG together with more frequent use of surgical treatment doubles survival. Systematic adherence to CG, timely prevention and implementation of the Endocarditis Team into practice play the decisive role in a favorable prognosis of dynamically changing IE. This article presents the authors' own data that confirm the evolutionary trends of current IE.