A Case of Acute Abdomen Caused by Enteroaggregative Escherichia coli

Abstract

Abstract

Background:

Surgeons are often challenged to make operative decisions in patients with acute abdominal pain. Recognition that an acute abdomen is a rare presentation of infectious colitis may prevent unnecessary operation. We present a patient with acute abdomen found to be from procto-colitis caused by enteroaggregative Escherichia coli.

Case Presentation:

A 56-year-old woman was seen for acute severe diffuse abdominal pain. She had a single episode of watery diarrhea. She had exquisite tenderness of the right side of the abdomen and lactic acidosis. She was afebrile and did not have leukocytosis. Computed tomography (CT) imaging showed thickening and inflammation extending from the right colon to the rectum. She was treated with bowel rest and antibiotic therapy. She was suspected of having an infectious colitis and stool cultures grew enteroaggregative Escherichia coli and no other enteric pathogens. She responded and was discharged in four days.

Conclusion:

Non-operative treatment of patients with acute abdominal pain caused by an infectious colitis should be considered. Despite having severe abdominal pain and lactic acidosis, our patient with enteroaggregative Escherichia coli procto-colitis responded to antibiotics and bowel rest.

Abdominal pain is the presenting symptom in up to 10% of all patient visits to the emergency department, and the majority of patients are typically discharged with non-specific and benign pain [1,2]. Of particular importance is the acute abdomen, which is any sudden, severe, and non-traumatic abdominal pain for which the underlying etiology can be inflammatory, ischemic, obstructive, infectious, gynecologic, or even metabolic in nature [3]. Infectious causes of acute abdomen are not as common as other etiologies, and in particular, enteroaggregative Escherichia coli (EAEC) colitis typically presents with watery diarrhea rather than severe abdominal pain [4]. Enteroaggregative E. coli was first described in 1987 and has since been shown to be one of the well-defined E. coli causing intestinal diseases [5]. Enteroaggregative E. coli is known to cause diarrhea in travelers to developing countries as well as in children and infants in developing countries, but it is now also recognized as a growing cause of sporadic diarrhea in healthy adults and children in developed countries [6].

Case Presentation

A 56-year-old African American female with a past medical history significant for hypertension, schizophrenia, gastroesophageal reflux disease (GERD), rheumatic fever, and hepatitis C presented to the emergency department with acute worsening of severe abdominal pain that began two days prior. Her pain was not associated with nausea, vomiting, fever, or chills. It was located in the bilateral lower quadrants of her abdomen and was severe, sharp, constant, and non-radiating. It was associated with abdominal distension and one episode of watery non-bloody diarrhea before admission. The pain was exacerbated by movement and slightly relieved with morphine administered in the emergency department. The patient denied association of the pain with food or bowel movements. She could not recall any inciting events, although she mentioned that she adopted a new cat three days prior to the onset of her pain. She denied consuming any unusual meals and had no history of sick contacts or recent travels. She had no prior abdominal surgeries, and the only significant family history was colon cancer in her mother. She admitted to a 20 pack-year history of smoking, occasional alcohol use, and recent illicit drug use (marijuana and cocaine).

On admission, her vitals were as follows: blood pressure, 116/57; heart rate, 81; respiratory rate, 18; temperature (temporal artery), 36.3°C; and oxygen saturation, 97%. On physical examination, she was alert, oriented but distressed. Her abdomen was moderately distended, soft but diffusely tender (worse in the right lower quadrant [RLQ]) with no rebound tenderness. The rest of her physical examination was unremarkable. Laboratory studies were significant for elevated lactate of 8.6 mmol/L and mild transaminitis without leukocytosis, anemia, platelet abnormalities, or electrolyte abnormalities. Abdominal radiograph showed a non-specific, non-obstructive bowel gas pattern with no free intra-peritoneal air. A CT scan of the abdomen and pelvis was then obtained that showed extensive chronic inflammatory changes of the entire colon with areas of active inflammation (Figs. 1 and 2). Stool samples were then obtained for cultures, ova and parasite testing, and Clostridium difficile toxin testing.

FIG. 1.

(A) and (B): Computed tomography (CT) showing colitis involving right colon, transverse colon, and splenic flexure

FIG. 2.

Computed tomography (CT) showing inflammatory process extending to rectum.

Because of her severe pain, CT scan findings and, elevated lactate the decision was made to admit the patient to the intensive care unit (ICU) for close monitoring and serial abdominal examination. She was continued on intravenous (IV) hydration, bowel rest, and pain control. She was also started on empiric IV antibiotics (metronidazole, piperacillin-tazobactam, and vancomycin). During the first 24 h of ICU stay, she had six more episodes of non-bloody, watery diarrhea without any nausea or vomiting. Over the next day, the patient's abdominal examination improved remarkably with only minimal tenderness. Stool pathogen panel came back positive for EAEC, and her antibiotic regimen was switched to a six-day course of oral ciprofloxacin 500 mg twice daily, and her diet was advanced as tolerated. She was discharged the following day with an oral antibiotic regimen, as she was no longer complaining of any pain and was tolerating a regular diet. Of note, our patient was never febrile nor had leukocytosis during her four-day hospital stay.

Discussion

The differential diagnosis for an acute abdomen includes a variety of medical and surgical conditions. Clinicians should be careful in obtaining a detailed history and physical examination to avoid unnecessary surgery. The final diagnosis of EAEC was unexpected, but the clinical decision-making process was logical. Although her initial presentation closely mimicked that of a surgical abdomen, many emergent problems such as acute appendicitis, small bowel obstruction, and perforated viscus were ruled out quickly with a careful history and physical examination, laboratory studies, and preliminary imaging. Such findings included absence of nausea or vomiting, ability to pass stool, normal vital signs, lack of peritoneal signs on examination, and free air on abdominal radiograph, and her normal white blood cell count. Another consideration, given the clinical presentation and history of hypertension and recent cocaine use, was ischemic colitis. A CT of the abdomen and pelvis was obtained and showed an acute or chronic pancolitis, but this finding was not convincing for ischemic colitis because more than one vascular supply would needed to have been compromised to achieve such an effect. In addition, there was no evidence of pneumatosis intestinalis or portal venous gas. Inflammatory bowel disease, in particular ulcerative colitis, was also considered given the presence of pancolitis; however, the age of the patient and sudden onset of abdominal pain with no prior abdominal symptoms or bloody diarrhea made this diagnosis less likely. Once the above mentioned conditions were worked up and thought to be unlikely, infectious colitis was considered as the most likely etiology of her abdominal pain. This presumption was supported by her quick improvement on antibiotic therapy and later confirmed by the gastrointestinal pathogen panel that showed EAEC.

Enteroaggregative E. coli is an infrequent but known type of pathogenic E. coli that is recognized increasingly as a cause of traveler's diarrhea, diarrhea in children in developing countries, and persistent diarrhea in patients with human immunodeficiency virus (HIV) [7]. The most common clinical manifestation of EAEC colitis is an afebrile patient with self-limiting watery diarrhea without blood or mucous [4]. Abdominal pain has been reported as an infrequent symptom of EAEC colitis, but as can be seen, it can be the most prominent and presenting symptom to the extent that it may imitate an acute surgical abdomen [6,8]. The severe abdominal pain in addition to the lack of other risk factors associated with EAEC such as travel or consumption of contaminated foods made the initial clinical suspicion of EAEC in our patient low. Because of this low clinical suspicion, HIV testing was not performed on our patient (although the patient tested negative in 2015). Even after the additional six diarrheal episodes in the ICU after admission, EAEC was not considered among the possible infectious etiologies. However, it is important for surgeons to be aware of EAEC colitis as a cause of acute abdominal pain (especially in patients presenting with diarrhea) to avoid unnecessary surgery in a patient that would otherwise improve with antibiotic therapy alone. Because many EAEC infections are self-limiting or asymptomatic, treatment is usually supportive with IV fluid hydration, however, in patients with symptomatic or severe disease, oral ciprofloxacin 500 mg twice daily for three to seven days or rifaximin 200 or 400 mg twice daily for three days has been shown to reduce the duration of diarrhea [7,9].