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Updated: Oct 12, 2025
A Neonatal Imaging Model of Gram-Negative Bacterial Sepsis
Published on: August 12, 2020
The microbial composition of the initial insult can predict the prognosis of experimental sepsis
Szabolcs Péter Tallósy1, Marietta Zita Poles1, Attila Rutai1
1Institute of Surgical Research, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary.
Abstract:
We hypothesized that the composition of sepsis-inducing bacterial flora influences the course of fecal peritonitis in rodents. Saline or fecal suspensions with a standardized dose range of bacterial colony-forming units (CFUs) were injected intraperitoneally into Sprague-Dawley rats. The qualitative composition of the initial inoculum and the ascites was analyzed separately by MALDI-TOF mass spectrometry. Invasive monitoring was conducted in separate anesthetized groups (n = 12-13/group) after 12, 24, 48 and 72 h to determine rat-specific organ failure assessment (ROFA) scores. Death and ROFA scores peaked at 24 h. At this time, 20% mortality occurred in animals receiving a monomicrobial E. coli suspension, and ROFA scores were significantly higher in the monomicrobial subgroup than in the polymicrobial one (median 6.5; 5.0-7.0 and 5.0; 4.75-5.0, respectively). ROFA scores dropped after 48 h, accompanied by a steady decrease in ascites CFUs and a shift towards intra-abdominal monomicrobial E. coli cultures. Furthermore, we found a relationship between ascites CFUs and the evolving change in ROFA scores throughout the study. Hence, quantitatively identical bacterial loads with mono- or polymicrobial dominance lead to a different degree of sepsis severity and divergent outcomes. Initial and intraperitoneal microbiological testing should be used to improve translational research success.
Insights
Bacterial composition significantly impacts sepsis severity in rodents. Monomicrobial infections led to higher organ failure scores and mortality compared to polymicrobial ones, highlighting the importance of initial microbiological assessment.
Area of Science:
- Microbiology
- Immunology
- Sepsis Pathophysiology
Background:
- Fecal peritonitis is a common cause of sepsis.
- The role of bacterial flora composition in sepsis progression is not fully understood.
Purpose of the Study:
- To investigate how the composition of bacterial flora influences the course of fecal peritonitis in a rodent model.
- To compare sepsis severity and outcomes between monomicrobial and polymicrobial infections.
Main Methods:
- Sprague-Dawley rats were injected intraperitoneally with standardized bacterial colony-forming units (CFUs) in saline or fecal suspensions.
- Bacterial composition was analyzed using MALDI-TOF mass spectrometry.
- Rat-specific organ failure assessment (ROFA) scores were monitored invasively over 72 hours.
Main Results:
- Sepsis severity, indicated by ROFA scores and mortality, peaked at 24 hours.
- Monomicrobial *E. coli* infections resulted in significantly higher ROFA scores compared to polymicrobial infections.
- A decrease in ascites CFUs and a shift towards monomicrobial cultures were observed after 48 hours, correlating with reduced ROFA scores.
Conclusions:
- The composition of bacterial flora, not just bacterial load, significantly affects sepsis severity and outcomes.
- Monomicrobial dominance in peritonitis leads to more severe sepsis than polymicrobial infections.
- Initial and intraperitoneal microbiological analysis is crucial for improving translational research in sepsis.
