Infective Endocarditis in Intravenous Drug Users: Surgical Treatment

Abstract

Intravenous drug use is associated with infective endocarditis. Besides, it does appear that left-sided infective endocarditis is a feature of general population, whereas right-sided infective endocarditis is common in intravenous drug users. The most common etiology of right-sided infective endocarditis in intravenous drug users is Staphylococcus aureus in about 75% followed by streptococci, Gramnegative bacilli and fungi. In case of intravenous drug users with infective endocarditis, optimal treatment strategies lack a general consensus. Additionally, the best indication and timing of surgery are debatable. To overcome these problems, the early and complete surgical debridement of infected tissue together with microbial therapy assures a good prognosis in the long term.Keywords: endocarditis, drug-associated endocarditis, intravenous drug abuser endocarditis, intravenous drug users, right heart endocarditis Infective Endocarditis 2 the right-sided IE, tricuspid valve is affected in 90% cases [21], whereas pulmonic valve represents about 10% from right-sided IE cases [3,18,24]. Up to now, isolated right-sided IE involving the pulmonary valve, the eustachian valve, interventricular septum, or right ventricular free wall have been described [17,21,25]. MicrobiologyAccording to current evidence, IE among IDUs presents a large spectrum of microbial pathogens (Table 1) [26][27][28][29][30][31].Pathogens as Pseudomonas aeruginosa, other gram-negative microorganisms, fungi, enterococci, streptococci, and polymicrobial infections occur less frequently [16]. Importantly, other pathogens noted in IDUs are oral bacteria such as Prevotella intermedia, Haemophilus parainfluenzae, S. constellatus, and E. corrodens [32][33][34][35][36].The most common etiology of right-sided IE in IDUs is Staphylococcus aureus (S. aureus) in about 75% [1,4,6,[37][38][39] followed by streptococci, Gram-negative bacilli, and fungi [40]. In fact, published data supports the involvement of S. aureus among IDUs in 40-74% cases of IE [38,41,42]. S. aureus is the most common cause of tricuspid valve endocarditis regardless of associated risk factors in IDUs [1,4,16,18,43].The incidence of negative blood cultures is reported as 2.5-31% and is associated with delayed diagnosis and treatment [44], with large vegetations [45], and with highest morbidity and mortality [16,45,46].Regarding HIV, a prevalence of HIV as high as 60% among IDUs has been reported by centers from Europe and the USA [11,40]. HIV is more common among IDUs with right-sided IE than left-sided IE [47].Polymicrobial endocarditis is characteristically for IDUs [48] and may involve microorganisms such as Bartonella spp., Candida spp., or Tropheryma whipplei [49]. The presence of E. corrodens should aware the likelihood of polymicrobial IE with embolic complications and relapses. In fact, there is a synergism between streptococci and E. corrodens [50][51][52].