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Enhancement of experimental anaerobic infections by blood, hemoglobin, and hemostatic agents
Abstract:
Certain foreign materials have been demonstrated to enhance the infectivity of aerobic and anaerobic bacteria. Whole blood and other protein compounds encountered in surgical settings or trauma were tested for their effect on infectivity of nonsporeforming anaerobic bacteria. Infectious synergistic mixtures of Bacteroides fragilis plus Peptostreptococcus anaerobius and Bacteroides melaninogenicus plus Fusobacterium necrophorum were each diluted to a barely noninfectious or minimally infectious concentration (subinfective inoculum) that was injected intraperitoneally into mice alone and in combination with test proteins. Infectivity was measured by deaths from sepsis or abscess(es) within the abdominal cavity at autopsy at 1 week. Two hemostatic agents, Gelfoam powder and Avitene (final concentrations, 10 mg/ml), and crystalline hemoglobin (4 g/100 ml) each produced a marked increase (P < 0.001) in the rate of infection when mixed with a normally subinfective inoculum of either bacterial mixture. Fresh homologous mouse blood (0.25 ml) injected intraperitoneally without anticoagulant also significantly enhanced infectivity (P < 0.01) of a subinfective inoculum of B. fragilis plus P. anaerobius. These studies demonstrated the capacity of whole blood, hemoglobin, and hemostatic agents to enhance the infectivity of certain nonsporeforming anaerobic bacteria. The high concentrations of anaerobic bacteria in the gastrointestinal, female genital, and respiratory tracts produce an increased risk of human infection after surgery or trauma in these sites; the protein agents studied here may further enhance infection.
Insights
Foreign materials like whole blood, hemoglobin, and hemostatic agents significantly increase the infectivity of anaerobic bacteria. This finding is crucial for understanding infection risks following surgery or trauma in certain body sites.
Area of Science:
- Microbiology
- Surgical Infection Research
Background:
- Foreign materials, including whole blood and protein compounds, can influence bacterial infectivity.
- Nonsporeforming anaerobic bacteria are frequently implicated in surgical site infections and infections following trauma.
Purpose of the Study:
- To investigate the effect of whole blood and protein compounds on the infectivity of nonsporeforming anaerobic bacteria.
- To determine if common surgical materials enhance bacterial infection risk.
Main Methods:
- Bacterial mixtures (Bacteroides fragilis/Peptostreptococcus anaerobius and Bacteroides melaninogenicus/Fusobacterium necrophorum) were diluted to subinfective concentrations.
- These inocula were injected intraperitoneally into mice, alone and combined with test proteins (hemostatic agents, hemoglobin, whole blood).
- Infectivity was assessed by monitoring deaths from sepsis or abscesses within one week.
Main Results:
- Hemostatic agents (Gelfoam, Avitene) and crystalline hemoglobin significantly increased infection rates (P < 0.001) when combined with subinfective bacterial inocula.
- Fresh homologous mouse blood also significantly enhanced infectivity (P < 0.01) of a Bacteroides fragilis/Peptostreptococcus anaerobius inoculum.
- These protein-rich materials demonstrated a capacity to potentiate the infectivity of certain anaerobic bacteria.
Conclusions:
- Whole blood, hemoglobin, and hemostatic agents can enhance the infectivity of specific nonsporeforming anaerobic bacteria.
- The presence of these agents may increase the risk of infection in surgical or trauma patients, particularly in areas with high concentrations of anaerobic bacteria.
- Findings highlight potential synergistic effects between biomaterials and bacteria in post-operative and trauma-related infections.