Patients with diabetes are almost three times more susceptible to life-threatening blood infections by Staphylococcus aureus bacteria, according to a study published in the European Journal of Endocrinology. These findings could indicate a need for greater infection surveillance among long-term diabetes patients.
S. aureus is a bacterium that normally lives harmlessly on the skin. Occasionally it causes infections, which can be fatal if the bacteria enter the bloodstream. The incidence of S. aureus infection has increased in the past 20 years driven by both known and unknown factors. The presence of this bacterium within the blood stream is a serious medical condition, with a 30-day mortality rate of 20-30%. This study found that, diabetes patients have a 2.8 times increased risk of S. aureus blood infection acquired outside of a hospital.
Researchers from Aalborg University Hospital and Aarhus University Hospital in Denmark analysed records of 30,000 people from four different medical registries in Denmark over a twelve year period. The team compared the risk of infection when taking into account different types of diabetes, how long patients had been diagnosed with the condition and other associated complications of living with diabetes.
Compared to patients without diabetes, people with type-1 diabetes were 7.2 times more at risk of S. aureus infection whereas people with type-2 were 2.7 times more at risk. Also more at risk were those suffering from other complications - such as heart and circulation problems, and diabetic ulcers. Kidney problems associated with diabetes were one of the highest risk factors, with a 4.2 times increased risk.
The risk of infection also increased with the number of years a patient had had diabetes; those who had suffered for 10 years or more were 3.8 times more at risk. The extent to which patients had control over their diabetes was also considered, with those with poor management of their diabetes showing a greater risk.
"It has long been a common clinical belief that diabetes increases the risk of S. aureus infection, but until now this has been supported by scant evidence," says lead author Jesper Smit. "Poor management of diabetes can lead to an impaired immune response. This may be the reason why diabetes patients are at higher risk of infection. Similarly, diabetic patients often suffer associated illnesses - the burden of multiple healthcare problems can also increase susceptibility to infection."
Following this study, the next steps will be to investigate how diabetes may affect the prognosis of blood infections of S. aureus, and determine how the increased risk factor of diabetes may correspond to disease outcome.
It is important to note the limitations of the study; the medical data available did not allow the researchers to adjust for smoking or body mass index in their sample - two factors which may affect the immune response and subsequent possible infection. It must also be noticed that methicillin-resistant S. aureus (MRSA) is rare in Denmark, and the epidemiology of S. aureus may be different in countries where MRSA prevails.