Epidemiological characteristics and management of Gram-negative bacteraemia in different immunocompromised hosts: Observational single-center study

Abstract

Importance: Patients with Gram-negative bloodstream infections (GN-BSI) are classified as non-immunocompromised (n-IC) or immunocompromised (IC). However, immunosuppressive condition should not be considered univocally.

Objective: To investigate epidemiological characteristics, management and outcome of GN-BSI in IC and non-IC patients.

Methods: Retrospective single-center study of hospitalized patients with GN-BSI conducted over a 7-year period. Patients with GN-BSI were divided in: solid organ transplant (SOT) recipients, patients with hematologic malignancy (HM), patients with metastatic solid cancer (mSC), and non-major IC patients (nm-IC).

Results: 3544 patients analysed: 76.7% nm-IC, 6.5% SOT, 8.0% HM and 8.8% mSC. SOT and HM patients were younger (SOT: 56.6 ± 13.1 years; HM: 56.4 ± 14.5; nm-IC: 72.4 ± 16.1; mSC: 68.6 ± 13.1, p < 0.001) and had lower CCI value (SOT: 4.5 ± 2.4; HM: 4.1 ± 2.1; nm-IC: 5.5 ± 2.6; mSC: 9.7 ± 2.5, p < 0.001). Urinary tract infection was the most common source of BSI in nm-IC (nm-IC: 50.1%, HM:15%; SOT: 33.3%; mSC: 25.9%, p < 0.001), intra-abdominal infection was the more frequent source among SOT and mSC (SOT:42.3%; mSC: 49.3%, nm-IC: 27.8%, HM:29%; p < 0.001). Primary BSI was the first cause of GN-BSI in HM (HM: 62.1%; SOT: 18.5%; nm-IC: 17.2%; mSC: 10.6%, p < 0.001). The lowest rate of death was observed in SOT and the highest in mSC (SOT 8.2%; nm-IC 13.4%; HM 14.9%; mSC 19.9%, p < 0.001). Relapse rate was highest in SOT (SOT: 18.8%; HM: 11.8%; NMIC: 7.2%; aST: 7.1%, p < 0.001). Follow-up bloodcultures were associated with a lower mortality only among NMIC (HR = 0.317, 95% CI 0.178-0.563, p < 0.001) and aST (HR = 0.198, 95% CI 0.058-0.673, p = 0.010). The role of treatment duration on relapse was not evident in any group, conversely receiving at least 7 days of treatment was associated with a lower risk of 90-day mortality in SOT and HM patients.

Conclusions: The characteristics and outcome of GN-BSI are peculiar between specific IC categories, therefore a personalized management should be implemented.

Fig 1. Study flow chart.

Legend: Flow chart illustrating patient inclusion, exclusion criteria, and final stratification for analysis. GN-BSI = Gram negative BSI.

Fig 2. Stacked cumulative incidence of 90-days relapse and death in patients with different duration of the antibiotic course – all patients.

Legend: Comparison of the cumulative risks of death and relapse among patients stratified by the duration of therapy. Patients receiving less than 7 days of therapy exhibited a higher risk of death compared to relapse.

Fig 3. Stacked cumulative incidence of 90-days relapse and death in patients with different duration of the antibiotic course by subpopulation.

Legend: Cumulative incidence functions for death and relapse for patients with SOT, HM, and mSC, stratified by treatment duration (<7 vs ≥ 7 days). SOT and HM patients exhibited a higher risk of relapse regardless of treatment length, while mSC patients showed a consistently higher risk of death. A ≥ 7-day therapy was associated with reduced mortality in SOT and HM subgroups. nm-IC = non major immunocompromised condition; SOT = solid organ transplantation; HM = haematological malignancies; mSC = metastatic solid cancer.