Flora

Gastrointestinal perforation typically leads to a polymicrobial infection. The types of organism involved depend on the level of perforation. Intestinal flora may also be altered by previous antimicrobial therapy or severe underlying disease. The normal flora of the stomach, duodenum, and proximal small bowel are sparse and similar to oropharyngeal flora. Low numbers of a-hemolytic streptococci, lactobacilli, Candida species, and anaerobes predominate. The distal small bowel contains larger numbers of organisms, including Enterobacteriaceae, Enterococcus species, and anaerobes.

Colonic perforation leads to hundreds of different species being introduced into the peritoneal cavity. However, once infection is established, the number is narrowed down to an average of five pathogens. The colon contains enormous numbers of bacteria, with more than 99.9% being obligate anaerobes, mostly of the Bacteroides fragilis group. B. fragilis and E. coli are the most frequently isolated organisms. Facultative organisms include E. coli, Proteus, Klebsiella, and Enterococcus species. E. coli has been shown to be responsible for sepsis and mortality in early peritonitis, while B. fragilis, in conjunction with E. coli and other flora, causes late abscess formation.

Clinical Presentation

Abdominal pain, nausea, vomiting, altered bowel habits, fever, and tachycardia are often present in patients with secondary peritonitis. Patients typically avoid movement and may keep their hips and knees flexed. Abdominal examination often reveals tenderness, involuntary guarding, and rebound tenderness. Hypotension due to sepsis and hypovolemic shock may occur with diffuse peritonitis, whereas patients with a localized abscess usually have minimal vital sign abnormalities.

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