Acute intraperitoneal infection with a hypervirulent Acinetobacter baumannii isolate in mice

Area of Science:

• Microbiology
• Immunology
• Infectious Diseases

Background:

• Acinetobacter baumannii is a critical pathogen causing healthcare-associated infections and is on the WHO priority list for antimicrobial resistance research.
• Catheter-related septicemia due to A. baumannii leads to high morbidity and mortality.

Purpose of the Study:

• To establish a reliable mouse model for studying A. baumannii infection, specifically septicemia.
• To investigate the host innate immune response, particularly the role of macrophages, in A. baumannii-induced septicemia.

Main Methods:

• A hypervirulent clinical strain (LAC-4) of A. baumannii was used to establish an intraperitoneal infection model in C57BL/6 and BALB/c mice.
• Immune cell recruitment, cytokine/chemokine production, and the effect of macrophage depletion were analyzed.

Main Results:

• The intraperitoneal infection model resulted in lethal or sublethal infections with high bacterial loads, mimicking septicemia.
• Infected mice exhibited neutrophil recruitment and produced pro-inflammatory cytokines and chemokines.
• Peritoneal macrophages played a crucial role in innate defense, as their depletion increased susceptibility to infection.

Conclusions:

• The developed mouse model is a valuable tool for studying A. baumannii pathogenesis and virulence factors.
• This model can be used for the rapid evaluation of new therapeutics and vaccines against A. baumannii septicemia.