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The infective dose of aerobic and anaerobic bacteria in postoperative wound sepsis
Abstract:
Surgery for perforated appendicitis was used to estimate the infective dose of aerobic and anaerobic bacteria in postoperative wound sepsis. The wound sepsis rates were 22.6% (7/31) after treatment with intravenous ampicillin sodium and metronidazole and 23.5% (8/34) after penicillin G sodium, streptomycin, and metronidazole, a nonsignificant difference. Intraoperative sampling by velvet pads demonstrated that the density of aerobes did not differ significantly from that of anaerobes, either on the surface of the appendix, in peritoneal exudate (aspirated), or in the wound before closure. The predominant pathogens were Escherichia coli and Bacteroides fragilis. In 15 patients who developed wound sepsis, the density of aerobes and anaerobes was significantly higher at all sampling sites than in 50 noninfected patients. The median infective dose of aerobes and anaerobes together was 4.6 X 10(5) colony forming units.cm-2 in the operative wound. There was a significantly high correlation between the densities of bacteria during operation and subsequent wound sepsis.
Insights
This study estimated the infective dose of bacteria causing wound sepsis after perforated appendicitis surgery. Higher bacterial densities in the operative wound correlated significantly with increased risk of postoperative wound infection.
Area of Science:
- Infectious Diseases
- Surgical Infections
- Microbiology
Background:
- Postoperative wound sepsis is a common complication following appendicitis surgery.
- Estimating the bacterial infective dose is crucial for understanding and preventing surgical site infections.
Purpose of the Study:
- To determine the infective dose of aerobic and anaerobic bacteria in relation to postoperative wound sepsis after perforated appendicitis surgery.
- To investigate the correlation between intraoperative bacterial densities and the incidence of wound infection.
Main Methods:
- Surgical wound sepsis rates were compared between two antibiotic regimens.
- Intraoperative bacterial sampling using velvet pads was performed on the appendix, peritoneal exudate, and wound before closure.
- Bacterial densities in infected versus non-infected patients were analyzed.
Main Results:
- No significant difference in wound sepsis rates was observed between the two antibiotic treatments.
- Intraoperative bacterial densities of aerobes and anaerobes were similar at all sampling sites.
- Significantly higher aerobic and anaerobic bacterial densities were found in patients who developed wound sepsis compared to uninfected patients.
- The median infective dose was estimated at 4.6 x 10^5 colony forming units/cm².
Conclusions:
- Bacterial density in the operative wound is a significant predictor of postoperative wound sepsis.
- The findings suggest a threshold for bacterial load that increases infection risk following perforated appendicitis surgery.