Background/Purpose: Infections are an important cause of mortality and morbidity in Systemic Lupus Erythematosus (SLE) patients. Different risk factors have been described for the development of infections in SLE, such as immunosuppressive therapy, intrinsic immune system dysfunction, disease activity, and lymphopenia. However, there is no current data on the potential risk factors for drug-resistant bacteria (DRB) in SLE. Bloodstream infections (BI) are common in SLE patients and are associated with increased mortality. An inadequate empirical antibiotic coverage in BI has been associated to higher mortality rates. Moreover, antibiotic resistance has become more prevalent, and it is important to define which patients require broad-spectrum antibiotics (BSA) initially. The aim of this study was to identify risk factors that influence the development of DBR in SLE, in order to determine which patients might benefit from an initial BSA coverage. 

Methods: A retrospective, case-control study was performed. All patients fulfilled at least four ACR 1997 criteria for SLE and had an episode of BI between 2001 and 2012. Cases were defined as patients who had BI caused by DRB (P. aeruginosa, methicillin-resistant S.aureus or extended-spectrum β-lactalamase-producing E. coli), while patients in the control group had BI by susceptible strains of S. aureus or E. coli. Groups were age and gender matched. The variables that were measured included: disease activity, SLEDAI, anti-dsDNA antibodies, C3 and C4 levels, leukocyte and lymphocyte count in the three months prior and at the time of the infection; comorbidities; use of antibiotics or hospitalization in the previous three months; immunosuppressive treatment in the previous year and at the moment of the infection. Differences between groups were analyzed by Student t test or U Mann-Whitney test. Association between variables was assessed by OR (CI 95%). Multivariate analysis was performed by binary logistic regression model. 

Results: Forty four patients were included in each group. 93% were female, with ages between 16 and 73. Variables associated with drug-resistant BI were the following: a history of CNS activity (OR 2.66, CI 95% 1.15-6.17); hematological activity (OR 2.11, CI 95% 1.07-4.14), immunosuppressive treatment (OR 1.24, CI 95% 1.02-1.5) and prednisone dose ≥ 20 mg/d at the time of the infection (OR 5.11, CI 95% 2-12.6); low C3 levels previous to infection (OR 2.71, CI 95% 1.25-5.9); and antibiotic use (OR 2.18, CI 95% 1.43-3.32) or hospitalization in the previous 3 months (OR 2.9, CI 95% 1.61-5.2). In the multivariate analysis, variables that remained significant were: low C3 previous to infection (OR 2.83, CI 95% 1.11-7.18), previous hospitalization (OR 2.18, CI 95% 1.21-3.95), and prednisone dose at the time of infection (OR 1.058, CI 95% 1.027-1.089). 

Conclusion: Low C3 levels, a recent hospitalization and prednisone dose at the time of infection are risk factors for developing BI caused by DRB in SLE patients. Patients with these characteristics may benefit from initial BSA coverage.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/drug-resistant-bloodstream-infections-in-systemic-lupus-erythematosus-patients-a-clinical-perspective/