Appendicitis Associated With Travelers’ Diarrhea Caused by Aeromonas sobria
Poh Lian Lim, MD, MPH, Department of Infectious Diseases, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433. E-mail: email@example.com
Aeromonas species is an infrequent pathogen causing travelers’ diarrhea and gastroenteritis. No human case of appendicitis has been reported as a complication of Aeromonas infection until now. We describe a case of acute appendicitis associated with Aeromonas sobria infection acquired in Cebu, Philippines.
Aeromonas, an enteric Gram-negative bacillus, has been associated with gastroenteritis, more commonly among children.1 It has been reported as an infrequent cause of travelers’ diarrhea2,3 and has been implicated in sporadic cases of bacteremia, cholangitis, septic arthritis, myonecrosis, and other infections, usually in persons with comorbid conditions or immunosuppression but also in healthy individuals with freshwater exposure.4
A variety of enteric pathogens have been associated with acute appendicitis, including Yersinia, Campylobacter, and nontyphoidal Salmonella species.5 Although there has been one reported case of left-sided segmental colitis,6 there have been no reports of acute appendicitis associated with Aeromonas species. We describe here a case of acute appendicitis in a traveler returning from the Philippines with Aeromonas-associated gastroenteritis.
A 46-year-old woman presented in June with fever and diarrhea of 3 days’ duration. Her medical history was notable for breast cancer in 2003 for which she had undergone lumpectomy, chemotherapy, and radiation therapy and had received tamoxifen for 4 years. She had traveled from Singapore to Cebu island in the Philippines 9 days prior to admission with a church group. Her trip was in rural areas and involved contact with children. She had not received any pretravel consultation or vaccinations before travel, did not observe food and water precautions, and reported consuming a mango shake with ice among other items prior to her illness.
Three days prior to admission, she developed acute onset of vomiting, abdominal pain, and watery diarrhea of up to 20 episodes per day. She was hospitalized in Lapu Lapu City for a presumptive diagnosis of amebiasis and treated with metronidazole. She decided to return to Singapore for medical care and was admitted to Tan Tock Seng Hospital. On admission, she had a temperature of 37.8°C, and her examination was notable for right lower quadrant tenderness with rebound and guarding. Initial blood tests showed a normal white blood cell count (6,100 cells/μL, with 74% neutrophils), normal chemistry, and liver function tests. Two sets of blood cultures were negative for bacterial pathogens. Stool examination showed 3+ leukocytes and no ova, cysts, or parasites.
A computerized tomography (CT) scan of her abdomen demonstrated a thickened appendix with periappendiceal fat stranding and mild generalized thickening of the entire colon. Surgical consultation was requested urgently, and she underwent a laparoscopic appendectomy. Operative findings indicated an acutely inflamed retrocecal appendix. Histopathology of the specimen showed acute mucosal inflammation, confirming the diagnosis of acute appendicitis.
Two separate stool cultures collected on hospital days 1 and 2 (illness days 4 and 5, respectively) subsequently grew Aeromonas sobria. The isolate was sensitive to ceftriaxone, ciprofloxacin, and trimethoprim–sulfamethoxazole and resistant to amoxicillin–clavulanate and tetracycline. The patient was treated with intravenous ceftriaxone on admission and, after her surgery, had an uneventful postoperative recovery and was discharged well.
This patient’s clinical presentation was characteristic for a case of severe travelers’ diarrhea, given the lack of pretravel advice and failure to observe food and water precautions. Her exposure to the pathogen would, therefore, not be entirely unexpected, given the presence of Aeromonas species isolated from drinking water samples in developing countries7 as well as retail fish samples sold in markets in the region.8 Isolation of A sobria from two separate diarrheal stool samples, in association with a compatible clinical presentation of gastroenteritis and incubation period, would suggest that Aeromonas was indeed the causative pathogen for her illness.
Pseudoappendicitis was considered initially, given her diarrheal symptoms and possible Campylobacter or Yersinia infection. However, her physical examination indicating an acute abdomen as well as the CT scan findings prompted surgical intervention because the risk of inadequate treatment for appendicitis was deemed greater than the converse risk of unnecessary surgery for pseudoappendicitis. This decision was borne out by the surgically and histologically proven diagnosis of appendicitis.
Aeromonas strains from clinical samples have been found to be resistant to a range of antibiotics. Investigating 863 patients with travelers’ diarrhea, Vila and colleagues2 found that in their 9 persons infected with Aeromonas veronii subtype sobria, the isolates were resistant to ampicillin (0% susceptible) but susceptible to chloramphenicol (67%), tetracyclines (56%), trimethoprim–sulfamethoxazole (78%), cefotaxime (100%), and ciprofloxacin (100%). A Hong Kong study of 40 cases of Aeromonas bacteremia, of which 8 were caused by A sobria, found similar antimicrobial susceptibility patterns.9 Third-generation cephalosporins or quinolones would be the drugs of choice for patients with severe Aeromonas infection.
Aeromonas-associated travelers’ diarrhea may be clinically indistinguishable from diarrhea caused by other pathogens. Vila’s review indicated that fever, crampy abdominal pain, and bloody stools occur in Aeromonas-associated cases at rates comparable to those previously been reported for travelers’ diarrhea10 (Table 1).
Table 1. Clinical features of Aeromonas-associated diarrhea compared to travelers’ diarrhea
|Nausea or vomiting||17||29–61|
Therefore, when evaluating returning travelers presenting with fever, abdominal pain and diarrhea, physicians need to maintain vigilance for unusual presentations of less common pathogens and respond to the issues occasioned by the patient’s clinical presentation.
Declaration of Interests
The author states that she has no conflicts of interest.