Methicillin-sensitive Staphylococcus aureus bacteremia in aged patients: the importance of formal infectious specialist consultation

Abstract

Background: Infectious specialist consultations (ISC) provide ever more evidence for improved outcome in Staphylococcus aureus bacteremia (SAB). Most ISC are formal (bedside). However, the impact of ISC on clinical management and prognosis lacks evaluation in aged patients with SAB. Methods: Multicenter retrospective analysis of methicillin-sensitive (MS) SAB. Patients were stratified according to age ≥ 60 years (sub-analyses for ≥ 75 years and females) and formal (bedside) ISC given within 7 days of SAB diagnosis. The impact on management and outcome of formal ISC was explored. Statistics were performed with univariate analysis, Cox proportional hazards regression model analysis, including propensity-score adjustment, and graphic Kaplan–Meier interpretation. Results: Altogether 617 patients were identified and 520 (84%) had formal ISC. Presence of formal ISC resulted in equivalent clinical management regardless of age over or under 60 years: localization and eradication of infection foci (80 vs. 82% and 34 vs. 36%) and use of anti-staphylococcal antibiotics (65 vs. 61%). Patients aged ≥ 60 years managed without formal ISC, compared to those with formal ISC, had less infection foci diagnosed (53 vs. 80%, p < 0.001). Lack of formal ISC in patients aged ≥ 60 years resulted in no infection eradication and absence of first-line anti-staphylococcal antibiotics. Formal ISC, compared to absence of formal ISC, lowered mortality at 90 days in patients aged ≥ 60 years (24 vs. 47%, p = 0.004). In Cox proportional regression, before and after propensity-score adjustment, formal ISC was a strong positive prognostic parameter in patients aged ≥ 60 years (HR 0.45; p = 0.004 and HR 0.44; p = 0.021), in patients aged ≥ 75 years (HR 0.18; p = 0.001 and HR 0.11; p = 0.003) and in female patients aged ≥ 75 years (HR 0.13; p = 0.005). Conclusion: Formal ISC ensures proper active clinical management irrespective of age and improve prognosis in aged patients with MS-SAB.