Evolution of antimicrobial resistance and mortality in Staphylococcus aureus endocarditis during 15 years in a university hospital

Abstract

Introduction. One of the most aggressive microorganisms in infective endocarditis (IE) is Staphylococcus aureus. We analyse the resistance of S. aureus to antibiotics and its impact on the clinical course of IE in a recent 15-year period. Methods. Retrospective study of patients with IE in a university hospital from 2005 to 2019. Bivariate and multivariate analysis of severity at admission, comorbidities, minimum inhibitory concentrations (MIC) and mortality. Results. Of the 293 IE cases, 66 (22.5%) were due to S. aureus, and 21 (7.2%) were methicillin-resistant S. aureus (MRSA). The prevalence of strains with a MIC to vancomycin ≥ 1mg/L increased from 4.8% to 63.6% (p <0.001) and the cases of MRSA from 38 to 27.3% (p = 0.045). Older age (p= 0.02), comorbidity (p <0.01) and nosohusial origin (p = 0.01), were factors associated with MRSA. But the antimicrobial resistance and severity on admission were not associated with exitus; predictive factors were the right-sided IE (OR = 0.08; 95% CI: 0.01-0.51), comorbidities (OR per Charlson index point = 1.30; 95% CI: 1.01-1.69) and creatinine on admission (OR per mg / dL = 1.56; 95% CI = 1.01- 2.35; p = 0.04). Conclusion. We have experienced an increase in IE cases with MIC to vancomycin ≥ 1mg/L, without significant variation in infections due to MRSA. Antimicrobial resistance was not associated with mortality, but comorbidity and left involvement were predictive factors.

Mortalidad de la Endocarditis Infecciosa en los Últimos 5 años

“…Un análisis multivariado de la mortalidad se asoció con: la edad, índice de Charlson, insuficiencia renal y shock séptico, y según el agente etiológico (16). Sin embargo, las conclusiones de un estudio sugieren que la resistencia antimicrobiana no se asoció a mortalidad, a diferencia de las comorbilidades y la afectación izquierda (17). Una ventaja que se ha desarrollado es la existencia de un modelo predictivo de mortalidad hospitalaria en EI izquierda basado en las variables pronósticas propuestas por las guías de EI de la Sociedad Europea de Cardiología tiene una alta capacidad discriminatoria, que se ve reflejado en los resultados del estudio, donde la muestra de validación interna (mortalidad observada: 29,9%) el modelo predice una mortalidad hospitalaria del 30,7% (IC95%, 27,7-33,7), y para la cohorte de validación externa (mortalidad observada: 27,1%) el valor fue 26,4 % (IC95%, 22,2-30,5) (18).…”