A Case of Staphylococcus aureus Enterocolitis

Staphylococcus aureus is a common organism found in nosocomial and postoperative infections. Enter-ocolitis caused by this organism can be severe and sometimes fatal.¹ In the 1950s and 1960s, S. aureus was implicated as a major pathogen in postoperative and antibiotic-associated enterocolitis.^2-5 Although it continued to be a problem in Japan,^1,6-8 its incidence in the United States has diminished.³ The clinical significance of S. aureus isolated from stool is unknown, as it is often seen unrelated to the clinical picture. We report a case of a patient with hemorrhagic enterocolitis who was initially suspected of having inflammatory bowel disease, but, based upon the diagnostic evaluation, was found to have S. aureus enterocolitis.

Case Report

A 49-year-old male hospital plumber with a history of hemorrhoids presented to an outside hospital with abdominal cramps and diarrhea. He was diagnosed with a gastrointestinal infection and was started on levofloxa-cin, metronidazole, and proton pump inhibitor therapy. The patient was discharged 2 days later but returned within 24 hours with worsened symptoms and bloody diarrhea. Computed tomography (CT) scan revealed thickening of the duodenum and jejunum (Figure 1), and enteroscopy revealed an ulcerated duodenum and jejunum with necrosis (Figure 2). Pathology showed moderatetosevere acute and chronic inflammation and acute inflammatory exudate.

Figure 1.

Abdominal computed tomography scan on Day 1 showed jejunal distention and thickening and no focal mass lesions or obstruction.

Figure 2.

Enteroscopy on Day 1 showed the duodenum with erythema, congestion, ulceration, friability, and inflammatory exudate (A and B) and the jejunum with erythema, congestion, ulceration, friability, necrosis, and inflammatory exudate (C and D).

The patient was transferred to Allegheny General Hospital in Pittsburgh, Pennsylvania. On admission, he was in mild distress and tachycardic and continued to complain of his initial symptoms. His abdomen was soft and mildly distended, with slightly hypoactive bowel sounds and mild diffuse tenderness. Relevant laboratory values included C-reactive protein of 13.9 mg/dL, erythrocyte sedimentation rate of 45 mm/hr, white blood cells of 24,100/mcL, neutrophils of 54,000/mcL, and bands of 40,000/mcL. Stool microscopic examination and culture were positive for many polymorphonuclear neutrophils and S. aureus. Stool culture was negative for Camplobacter, Shigella, Salmonella, and Yersinia. Repeat CT scan showed thickened terminal ileum and right colon, and work-up for hypercoagulable state and ischemia were negative. The patient was started on intravenous fluids and continued on flouroquinolone, metronidazole, and proton pump inhibitor therapy. Surgical consultation was obtained. The patient's symptoms gradually improved, but bandemia persisted. Upper gastrointestinal small bowel followthrough showed flocculation of the ileum. On Day 10, a repeat enteroscopy was normal to the jejunum (Figure 3A). Also on Day 10, a flexible sigmoidoscopy showed erythema, congestion, ulceration, friability, and exudate from the rectum to the splenic flexure (Figure 3B–D). On Day 12, the patient's clinical status worsened, and he was taken to surgery. Exploratory laparotomy revealed a toxic megacolon, and a gram stain from the surgical specimens revealed gram-positive cocci in clusters (Figure 4). Histo-pathology from the colon and ileum resections showed chronic active colitis with cryptitis and crypt abscesses, focal mucosal inflammation and transmural acute inflame-mation, and ulceration and necrosis (Figure 5).

Figure 3.

Enteroscopy and sigmoidoscopy on Day 10 showed diffuse continuous erythema, congestion of the mucosa, and friability in the proximal jejunum (A); erythema, congestion, ulceration, friability, and exudate in the descending colon (B) and (C); and erythema, congestion, ulceration, friability, and exudate in the rectum (D).

Figure 4.

Gram stain revealing gram-positive cocci in clusters.

Figure 5.

Colon with ulceration and necrosis.

Postoperatively, the patient's symptoms resolved. He was discharged without antibiotic therapy and remained in clinical and endoscopic remission at the 6-and 12-month follow-up visits.

Discussion

S. aureus necrotizing enterocolitis has most commonly been described in patients with severe underlying disease, previous gastrectomy, use of antipeptic ulcer drugs, recent antibiotic use, and in patients previously colonized with methicillin-resistant S. aureus.^3,4,9,10 Symptoms of S. aureus necrotizing enterocolitis include nausea, vomiting, diarrhea associated with fever, and evidence in the stool of an acute inflammatory process affecting the gut mucosa (ie, pus, mucus, or blood).^5,9 Additionally, dysentery with crampy abdominal pain and tenesmus may be present. Radiologic findings are nonspecific but may show bowel thickening. Endoscopic findings are also nonspecific and may include patchy erythematous areas, pseudomembranous disease, and ulcerations with necrosis.^5,9 Pathologic findings include acute patchy necrotizing disease, which can progress rapidly to complete structural necrosis and segmental gangrene. The diagnosis of S. aureus enterocolitis is often made by clinical history and exclusion of other enterocolitides; gram stain of biopsy specimens; and isolation of S. aureus from the stool.

In this case report, the patient had received broad-spectrum antibiotics and empiric acid suppression and was at a high occupational risk for a nosocomial infection. Although endoscopic and pathologic findings may suggest Crohn's disease, necrosis on pathology and endoscopic remission of duodenal and jejunal pathol-ogy within days of antibiotic therapy are not typical findings of acute and chronic Crohn's disease. Signs and symptoms consistent with S. aureus necrotizing enterocolitis in this patient included bloody diarrhea, thickening of the duodenum and jejunum on CT, and an ulcerated duodenum and jejunum and necrosis on enteroscopy. Furthermore, endoscopic and surgical specimens revealed grampositive cocci in clusters, and pathologic findings showed ulceration and necrosis. Medical therapy with oral vancomycin has been shown to be effective,^3,4,6 but surgery may be required for more advanced disease, such as in the present case. This case helps bring awareness to the existence of a rare entity.