Muscle weakness in a S. pneumoniae sepsis mouse model

Area of Science:

• Critical Care Medicine
• Neurology
• Immunology

Background:

• Intensive care unit-acquired weakness (ICU-AW) affects peripheral nerves and muscles, but its pathophysiology is complex and not fully understood.
• A translatable and easily applicable animal model for ICU-AW is currently lacking.
• This study aimed to evaluate a mouse model of Streptococcus pneumoniae sepsis for its potential to mimic ICU-AW.

Purpose of the Study:

• To investigate the potential of a Streptococcus pneumoniae sepsis model in mice as a tool for studying ICU-AW.
• To assess in vivo limb and diaphragm muscle strength, as well as electrophysiological parameters, in this sepsis model.

Main Methods:

• C57BL/6J mice were intranasally inoculated with Streptococcus pneumoniae.
• Mice received ceftriaxone at varying times post-infection or based on body weight loss.
• In vivo grip strength, electrophysiological recordings, and ex vivo diaphragm muscle fiber strength were assessed.

Main Results:

• No significant differences in grip strength or electrophysiological recordings were observed between sepsis and control groups.
• Ex vivo diaphragm muscle fiber contractility was reduced in mice treated with ceftriaxone 48 hours after S. pneumoniae inoculation.
• The model did not fully replicate the clinical presentation of ICU-AW.

Conclusions:

• The S. pneumoniae sepsis mouse model induced ex vivo diaphragm weakness but not in vivo limb weakness.
• This model does not fully represent the human ICU-AW clinical picture.
• The model may be valuable for investigating inflammation-induced diaphragmatic weakness.