Longitudinal evaluation of risk factors and outcomes of blood stream infections due to Staphylococcu s species in persons with HIV: An observational cohort study

Abstract

Background: Staphylococcal blood stream infections (SBSI) are a significant cause of morbidity and mortality, however there is little data on such infections in persons with HIV (PWH) in the combination antiretroviral therapy era, particularly when divided by species; methicillin-sensitive (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative Staphylococcus (CoNS).

Methods: Using linked longitudinal clinical and microbiologic databases, all cases of SBSI in PWH accessing care at Southern Alberta Clinic were identified and demographic features and outcomes characterized. We compared participants with SBSI to those with no SBSI and determined the 1-year all-cause mortality following SBSI and longitudinally over the study period.

Findings: From 2000 to 2018, 130 SBSI occurred in 95 PWH over 21,526 patient-years follow-up. MSSA caused 38.4%, MRSA 26.1% and CoNS 35.3% of SBSI. Highest risks for SSBI were in Hepatitis C coinfection, low CD4 nadir, Indigenous/Metis ethnicity and in persons who use injection drugs (PWID). During follow-up, 423 deaths occurred in all PWH. Mortality rates for PWH with SBSI was 74.9/1000 patient-years (95% CI 59.2-94.9) compared with no SBSI 16.0/1000 patient-years (95% CI 14.4-17.7). The mortality Hazard Ratio was 2.61(95% CI 1.95-3.49, P= <0.001) for SBSI compared to no SBSI, following adjusting for confounding. Seventy deaths occurred in persons with SBSI with 40% in the first year. Higher 1-year mortality rates occurred in hospital-acquired infections.

Interpretation: Incidence rates of SBSI are high in PWH, with identified characteristics that further increase this risk. PWH who experience SBSI have a significant mortality risk within the first year of follow-up, however they also have greater long-term all-cause mortality compared to those with no SBSI. Further investigation is needed in PWH evaluating host, environment and pathogen differences that lead to differing rates of SBSI and mortality seen here.

Funding: No funding was received for this work.

Keywords: Bloodstream infections; Coagulase negative staphylococcus; HIV/AIDS; Outcomes; Staphylococcus aureus.

Fig. 1

Flow diagram for inclusion into the study population.

Fig. 2

Comorbidities/coinfections in PWH at SAC between 2000 and 2018 comparing those with SBSI to those without SBSI. HCV ab = hepatitis C antibody positive (n = 2824 no SBSI, n = 104 SBSI), Syphilis EIA = syphilis enzyme immunoassay (n = 1566 no SBSI, n = 49 SBSI), CVA = cerebrovascular event, TB=tuberculosis, defined as current disease or latent. Liver disease is defined as all cause; including persons with cirrhosis or hepatitis. Diabetes including both insulin dependent and not insulin dependent. Neutropenia defined as absolute neutrophil count <500/mm³. (n = 3253 no SBSI, n = 130 SBSI, unless otherwise specified).

Fig. 3

Cumulative Survival Curve for PWH with SBSI compared to those without. The mortality rate was greater in those who had SBSI at 74.9/1000 PY (95% CI 59.2–94.9) compared to those with no SBSI at 16.0/1000 PY (95% CI 14.4–17.7) generating an unadjusted mortality Hazard Ratio (HR) for SBSI of 4.88 (95% CI 3.77–6.32 P <0.001).

Fig. 4

Cumulative 1-year Survival Curve following SBSI episodes in PWH for MSSA, MRSA and CoNS. (n = 130).