Abstract

Infective endocarditis is a life-threatening disease caused by bacterial infection of the endothelium and cardiac valves, either native or prosthetic. In the present work the role of the new microbiological techniques (techniques of detection and amplification of the subunit 16 ribosomal sRNA by means of the chain reaction of the polymerase in blood or tissue, fluorescent in situ hybridization, and matrix-assisted laser is reviewed desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS) in the diagnosis of infective endocarditis. Infective endocarditis (IE) is a life-threatening disease caused by septic vegetations and inflammatory foci on the surface of the endothelium and the valves. Although most of endocarditis cases are community-acquired, healthcare-associated endocarditis is increasing and now accounts for approximately one third of IE. Risk factors include the presence of a prosthetic heart valve, structural or congenital heart disease, intravenous drug use and a recent history of invasive procedures. Diagnosis is made using the Duke criteria, which include clinical, laboratory and echocardiographic findings. IE associates high morbidity and a mortality rate close to 25% in the year following diagnosis, thus early diagnosis and adequate treatment is fundamental in its evolution [1].

Most IE, regardless of valve type, native or prosthetic, are due to gram-positive cocci. Currently Staphylococcus aureus is the microorganism most frequently involved, causes 25% to 30% of cases, followed by viridans group Streptococci (20-25%), coagulase negative Staphylococci (11%) and Enterococcus faecalis 10% [2]. Gram-negative bacilli make up 5% of cases and include organisms from the HACEK (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella species) group, Enterobacteriaceae and nonfermenting Gram-negative bacilli. Finally, there is a series of microorganisms difficult to grow in conventional media that can cause IE, the most common being Coxiella Burnetii, Bartonella spp and Tropheryma whipplei and rare cases of IE caused by fungi [3,4]. With traditional microbiological methods, up to one third of IE remain without an etiological diagnosis [5,6]. This is usually due to two factors: the prior taking of antibiotics, which causes a lower yield of blood cultures, and the local prevalence of fastidious microorganisms that are difficult to isolate with conventional microbiological techniques or uncultivable or challenging to cultivate organisms in routine methods [7]. In recent years, various identification techniques have been developed, both in blood cultures and valvular tissue, which entail shorter times and greater diagnostic precision [8], thus reducing the percentage of blood culture negative IE (BCNE)