Endocarditis Caused by Staphylococcus aureus

Abstract

Staphylococcus aureus is the leading cause of infectious endocarditis and its mortality has remained high despite better diagnostic and therapeutic procedures over time. We conducted a retrospective review of 133 cases of definite S. aureus endocarditis seen at a single tertiary care hospital over 22 years to assess changes in the epidemiology and incidence of the infection, manifestations, outcome, risk factors for mortality, and impact of cardiac surgery on prognosis.Patients were classified into 2 groups: 1) right-sided endocarditis (64 patients) and 2) left-sided endocarditis (69 patients). While the number of cases of left-sided endocarditis remained steady at 1-3 cases per 10,000 admissions, the incidence of right-sided endocarditis, after a peak in the early 1990s, declined to almost disappear in 2001. Among the cases of right-sided endocarditis, we found 2 subsets of patients with different clinical features and prognosis: the first subset comprised 53 intravenous drug abusers, and the second subset comprised 11 patients with catheter-associated S. aureus bacteremia and endocarditis. Fifty-one patients were human immunodeficiency virus (HIV)-positive drug abusers, most of whom (80.3%) had right-sided endocarditis. We did not find differences in mortality between HIV-positive and HIV-negative individuals; mortality seemed to depend more on the site of the heart involved than on HIV status.Among the cases of left-sided endocarditis, the mitral valve was more commonly involved than the aortic valve (61% vs. 30%). Overall, 74% of patients with left-sided endocarditis developed 1 or more cardiac or extracardiac complication. In comparison, only 23.4% of patients with right-sided endocarditis developed complications.Prosthetic valve endocarditis (PVE) was hospital-acquired more frequently than native valve endocarditis (NVE). Patients with PVE had a shorter duration of symptoms until diagnosis and presented with or developed cardiac murmurs less frequently than patients with NVE. Cardiac failure (49%), renal failure (43%) and central nervous system (CNS) events (35%) were frequently observed in patients with both PVE and NVE. Valve replacement was more frequently needed and more rapidly performed in patients with PVE than in their counterparts with NVE.The overall mortality of patients with right-sided endocarditis was 17%. While the mortality of right-sided endocarditis in injection drug users was 3.7%, the mortality of patients with right-sided endocarditis associated with infected intravenous catheters was 82% (odds ratio [OR], 0.01; 95% confidence interval [CI], 0.001-0.07). For left-sided endocarditis mortality was 38% and was not significantly different in patients with NVE or PVE (OR, 0.65; 95% CI, 0.23-1.87). CNS complications were associated with mortality in both NVE (OR, 6.55; 95% CI, 1.78-24.04) and PVE (OR, 32; 95% CI, 2.63-465.40). Development of 2 or 3 complications was associated with an increased risk of mortality (OR, 5.59; 95% CI, 1.08-28.80 and OR, 9.25; 95% CI, 1.36-62.72 for 2 vs. 1 compli...

Staphylococcus aureus Infections: Epidemiology, Pathophysiology, Clinical Manifestations, and Management

“…Cases of health care-associated IE were more likely to be caused by S. aureus (125,133,142). Thus, in contrast to previous IE series where S. aureus comprised Ͻ10% of cases (71,145), S. aureus is now consistently the cause of IE in Ͼ25% of cases (125)(126)(127)(128)(129)146). …”

“…Several studies have concluded that all patients with S. aureus prosthetic valve IE, regardless of whether they have complications, benefit from surgery, citing the lower mortality rates found with the combination of medical and surgical treatments (146,152,153,183,(229)(230)(231)(232). For example, Fernandez Guerrero et al found that of the 65% of patients who underwent valve replacement surgery, only 15% died, whereas all of the 35% of patients who did not receive surgery died (146).…”

“…El-Ahdab et al (153) found that of patients with SAB and a prosthetic valve who underwent TEE, 23% showed valvular vegetation and 11% showed evidence of a valvular abscess. Patients with S. aureus prosthetic valve IE generally develop a new murmur less frequently than do patients with S. aureus native valve IE (146) and typically have a shorter duration of symptoms before a diagnosis is made (146).…”

“…In addition, consistent predictors of mortality are increasing age, stroke, and heart failure (125,170). Stroke is a grave but frequent complication arising from S. aureus prosthetic valve IE, afflicting 23 to 33% of patients (177,182,183), and is a significant prognostic indicator of mortality (146,177,182,183). Sohail et al found that of patients with S. aureus prosthetic valve IE, an American Society of Anesthesiologists class IV status and the presence of bioprosthetic (compared to mechanical) valves were also independent predictors of mortality (177).…”

“…The clinical manifestations of S. aureus IE are now well understood through the ICE-PCS cohort (125) as well as national cohorts (170) and long-term single-center studies (146,171,172). Patient characteristics associated with S. aureus IE include injection drug use, health care-associated infections, a shorter duration of symptoms prior to diagnosis, persistent bacteremia, the presence of a presumed intravascular device source, stroke, and diabetes mellitus (125,171).…”