S aureus Bloodstream Infection Linked to Risk for Myocardial Infarction

According to data published in Clinical Infectious Diseases, community-acquired Staphylococcus aureus bloodstream infection (CA-SABSI) is associated with an increased short-term risk for myocardial infarction (MI), which, in turn, is associated with subsequent mortality.

A recent case-control and self-control design study identified an association between S aureus infection and acute MI, leading investigators to assess the association of CA-SABSI with MI in the year after blood cultures.

This cohort study included 5157 CA-SABSI cases matched to 10,146 blood culture-negative control participants who had blood cultures collected at hospital attendance and were matched to the CA-SABSI by sex, 5-year age strata, and year of culture collection. Investigators also linked pathology information to hospital administrative data and an index of relative socio-economic advantage and disadvantage.

Mortality was significantly higher in the CA-SABSI group compared with control participants, at 10.9% vs 5.1%, respectively, at 365 days (P <.0001). There were 89 (1.7%) and 37 (0.4%) MI diagnoses in the CA-SABSI and control groups, respectively, in the 7 days after index blood cultures, excluding recurrent events. Multivariable logistic regression-demonstrated CA-SABSI remained significantly associated with MI after adjusting for known risk factors (OR 5 [95% CI, 3.3-7.5; P <.0001). In a Cox proportional hazard model, MIs occurring in this short-term risk period were associated with all-cause mortality (OR 1.7; 95% CI, 1.2-2.4; P <.005).

Investigators reported several study limitations, including the reliance on International Classification of Diseases, 10th Revision (ICD-10) administrative coding data compiled in databases, which is not designed for research purposes. According to investigators, previous work has suggested ICD-10 coding is of limited use for detecting severe sepsis in critically ill patients. “This limits the interpretation of severe sepsis and shock as a modifying variable designed to reduce the proportion of type II myocardial infarction as contributors,” said the investigators.

They also noted an inability to assess complicated vs uncomplicated CA-SABSI or prescribed cardiac medications for their cohort.

The link between CA-SABSI and MI found here warrants prospective studies, advised investigators. “The association itself warrants consideration for inclusion in cardiac risk assessment for this cohort of patients, and if causation can be demonstrated inflammatory modulators may have long term disease modifying effects,” they concluded.

Reference

McNamara JF, Harris PNA, Chatfield MD, Paterson DL. Acute myocardial infarction and community-acquired Staphylococcus aureus bloodstream infection: an observational cohort study. [published online August 14, 2020]. Clin Infect Dis. doi: 10.1093/cid/ciaa1197