Stroke enables gut bacteria to spread

Australian researchers have revealed that stroke injury can compromise the immune system, enabling bacterial pathogens to take an opportunistic journey from the gut into other organs — including the lungs.

As explained by CQUniversity’s Dr Dragana Stanley, first author on the study, infections such as bacterial pneumonia are common in stroke patients and often lead to death. She said the research team has proposed a major reason for the ineffectiveness of current treatments in fighting post-stroke infection.

“Post-stroke infection is likely to be contributed by the dissemination of diverse and largely antibiotic-resistant strains of bacteria that originated from the gut of the patient,” Dr Stanley said, noting that our hugely diverse gut bacteria outnumber our own cells 10 times and contain many pathogens.

“Usually our immune system keeps these gut bacteria under control, but a shock to the system, such as in a stroke, can compromise immunity, enabling bacteria to travel from the gut into organs including the lung, liver and spleen,” she said.

“We’ve shown that stroke injury can induce profound cellular changes and changes to barrier functions in the gut.

“We are suggesting that bacteria found in the post-stroke peripheral tissue appear to come from the gut microbiota.”

The discovery has been published in the journal Nature Medicine and may change the management of stroke patients, reducing the use of unnecessary and ineffective antibiotics.