Staphylococcus aureus blood infection 30% more fatal in women than men, but the reasons remain unclear.

Clinicians around the world have long suspected that bacteraemia due to Staphylococcus aureus has a worse outcome in women compared to men, but direct evidence has been elusive. A study just published confirms that significantly more women than men diagnosed with Staphylococcus aureus bacteraemia (SAB) - a blood infection of the common bacteria - die within 30 days.

Researchers from Denmark and Spain analysed data on 2,638 patients diagnosed with bacteraemia caused by Staphylococcus aureus. The study authors extracted data from population-based medical registers in Denmark from 2000 and 2011.

When they assessed deaths within the first 30 days, they found that 29% of the women died compared to 22% of the men. Women therefore are 1.3 times more likely to die within a month of developing Staphylococcus aureus bacteraemia (adjusted hazard ratio = 1.30 [95% CI; 1.11-1.53]).

The findings were published in Clinical Microbiology and Infection.

"It is worth noting that the link between gender and fatality was seen across all age groups and the greatest risk of death appeared to be in women who were diabetic or who had a diagnosis of chronic pulmonary disease or cancer," comments Dr. Jesper Smit from the Aalborg University Hospital, one of the study's authors.

The researchers found no link between gender and two common complications of Staphylococcus aureus bacteraemia: infective endocarditis and osteomyelitis.

"Although we now know that women in this situation are at a higher risk of death compared to men, we do not yet understand why," says Smit. "Further studies are needed to uncover the cellular and molecular mechanisms but the information we have generated should aid clinical decision making by helping to define which patients are most vulnerable," he adds.

The authors recommend that gender should be considered in the triage and risk stratification of patients with community-acquired Staphylococcus aureus bacteraemia.

Clinical Microbiology and Infection is the official journal of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID).

Article: Gender differences in the outcome of community-acquired Staphylococcus aureus bacteraemia: a historical population-based cohort study, J. Smit, L.E. López-Cortés, A.J. Kaasch, M. Søgaard, R.W. Thomsen, H.C. Schønheyder, J. Rodríguez-Baño, H. Nielsen, Clinical Microbiology and Infection, doi: 10.1016/j.cmi.2016.06.002, published online 22 June 2016.