Schweizerischer Nationalfonds / Fonds national suisse
Women with severe burn injuries are more likely than men to develop blood poisoning
Bern (ots)
Bacteria in the bloodstream can result in life-threatening complications for burn victims. Women are more susceptible to this than men, according to the unexpected results of a study funded by the SNSF.
The skin forms a natural barrier that prevents bacteria entering the body. Severe burns stop this pro-tective function from working properly, and germs can enter the blood more easily through the wounds. If the airways have suffered thermal or chemical injury through the inhalation of hot and toxic substances, they are also a gateway for infection.
The bacteria can multiply in the blood and spread throughout the body. In the worst case, this can cause blood poisoning - also known as sepsis - which can lead to multiple organ failure. This is a common cause of death in people with burn injuries. A study* supported by the SNSF has identified for the first time which patients are affected by such infections. The study was carried out before the disaster in Crans-Montana, but it can now help to better understand the physiological processes in critically ill burn patients.
The study focused on sex-specific differences. It analysed data from 269 patients with severe burn injuries who were treated at the Center for Severe Burn Injuries at the University Hospital Zurich be-tween 2017 and 2021. The insights from the study should help to prevent sepsis in patients with severe burn injuries or get it under control at an early stage.
The female body is often better at fighting infections
The study looked at whether and when bacteria appear in the blood of burn victims. Bacteraemia (bacteria in the blood) can develop into sepsis. The study found that just under a quarter of the pa-tients developed bacteraemia between five and thirteen days after admission. The analysis also showed that women were almost twice as likely to be affected.
"This finding came as quite a surprise to us," says Silvio Brugger, senior attending physician in the De-partment of Infectious Diseases and Hospital Epidemiology at Zurich University Hospital. "Because, actually, bloodstream infections are usually less common in women than in men."
It is well known that there are differences between the sexes in terms of bacterial infections. For ex-ample, in young women, bacterial infections tend to affect the upper airways, so the ears, nose and throat, whereas in men they are more likely to affect the bronchi and the lungs. Women are also more susceptible to bladder infections. Many of the differences can be explained by physique, hormonal factors and external circumstances such as occupational exposure or risk behaviour.
"Women's immune systems often seem better able to cope with pathogens, and a number of studies have observed a stronger immune response," says Brugger. In burn victims, however, it seems that this is not necessarily the case. The researchers are not yet able to answer the question of why the women with severe burn injuries in this cohort were much more likely to develop bacteraemia.
One explanation that can be ruled out, however, is the presence of different pathogens, as predomi-nantly the same bacteria were identified in the blood of male and female patients. "These are species that colonise the skin and mucous membranes as part of the natural microbiome," says Brugger. They are usually harmless but can become dangerous if they enter the bloodstream in large quanti-ties.
Oestrogen could be critical
The researchers plan to conduct a follow-up study to analyse the samples collected more closely in terms of sex hormones and the composition of the skin and airway microbiome. Sex hormones have an effect on human immune cells, which also fight infections. Female sex hormones such as oestrogen are actually associated with a better response. "But it is possible that burn injuries alter hormone me-tabolism, which then weakens the immune response," speculates Brugger.
Working with teams from intensive care medicine and plastic surgery, the researchers are now keen on examining the biological mechanisms behind these results more closely, because: "Advances in burn medicine have massively improved the chances of survival after burn injuries in recent decades." However, bacterial blood infections are still a problem.
While patients are usually given antibiotics early to fight the bacteria, the damaged barrier means that new infections keep occurring. Resistant bacteria can also quickly develop, for which very few effective antibiotics are available.
A better understanding of the underlying mechanisms would allow measures to be developed to better protect patients from bacteraemia. It may be some time before this is incorporated into medi-cal guidelines.
The text of this news and further information are available on the website of the Swiss National Science Foundation.
Contact:
Silvio Brugger
University Hospital Zurich
Phone: +41 44 255 33 22
silvio.brugger@usz.ch