A Young Girl Returns From Senegal with Dysentery

Case Report

The patient was a previously healthy 5-year-old girl who had returned 3 days prior to admission from a 1-month stay in Senegal, West Africa, after visiting relatives. She had stayed in a suburban area and eaten local foods. She had not been swimming, and there were no known direct exposures to animals. She had been well in Senegal until 6 days prior to admission when she began to develop multiple episodes of watery, then bloody, stools and tactile fever. Over the next few days she continued to have bloody diarrhea and also had decreased activity, diffuse abdominal pain, and poor oral intake. She was seen by a physician in West Africa who started her on metronidazole (Flagyl) and amoxicillin/clavulanate (Augmentin). Her symptoms persisted, however, and her father ultimately decided to bring her home to Connecticut.

Upon return, her pediatrician discontinued the antibiotics she had received in Africa, sent off laboratory studies, and offered supportive treatment. She appeared fairly well in the doctor’s office and she was sent home with instructions to return if symptoms worsened. That evening, her parents decided to bring her to the pediatric emergency department because of persistent diarrhea and fever. In the emergency department, she was febrile to 39.2°C, and on examination she had diffuse periumbilical tenderness without rebound. She had neither lymphadenopathy nor hepatosplenomegaly. Lung and heart sounds were normal. There were no rashes. She was found to be dehydrated (5-10%) with significant hyponatremia (serum Na+ 119 meq/l). White blood cell count was 28,700/ul with 21% segmented neutrophils and 32% band forms. Platelets were 368,000/ul, and she had a normal hemoglobin and hematocrit. She was started empirically on intravenous cefotaxime at 200 mg/kg/d. Blood and stool cultures were positive by the second day of hospitalization for Shigella dysenteriae. Antibiotics were changed to Ceftriaxone (75 mg/kg/d) based on the susceptibility pattern of the isolated organisms. She finished a 1-week course of intravenous therapy; her symptoms slowly resolved without additional complications and she was discharged to home.

Comment by Melissa Held, MD

Diarrhea is a common problem, often affecting travelers to developing countries. Bacterial agents may be identified in up to 85% of travelers with diarrhea lasting for less then 2 weeks. Destination represents one of the major risk factors for the development of diarrhea. People who visit friends or relatives during international travel are at increased risk over other travelers for becoming ill.1 They are more likely to stay in small towns or villages, to eat local food, and to drink from the local water supply. These travelers are also more likely than traditional tourists to be exposed to pathogens in the environment and are less likely to obtain their recommended vaccinations or medications. In assessing risk, the health care provider should consider the length of stay in the area, areas of exposure (jungle, rural, urban), and level of accommodations (camping, hotels, backpacking).2 Younger adults may be at higher risk of acquiring an infection secondary to a more adventurous itinerary and style while traveling. Children may be especially vulnerable since they likely have not been previously exposed to pathogens in the foreign environment and have an increased risk of fecal-oral contamination.6 Parents who are foreign-born may already have both disdain and immunity to a number of pathogens they may be exposed to while traveling.

Shigella spp. are some of the most common causes of bloody diarrhea or dysentery. In the United States, Shigellae are most often isolated from children younger than 5 years of age who have symptoms of bacillary dysentery. Organisms are easily transmissible, and only a small number are required to cause disease. There are 4 general species, with at least 41 major serotypes overall. Shigella sonnei is the most common species encountered within industrialized countries, followed by S flexneri. S boydii and S dysenteriae are less commonly found. A population-based study of the incidence of Shigella infections and causative serotypes in Santiago, Chile, among 7489 children younger than 60 months of age, showed that 4 serotypes, S sonnei (45%), S flexneri 2b (19%), S flexneri 2a (14%), and S flexneri) serotype 6 (11%) accounted for 89% of all cases. In this study, no isolations of S dysenteriae were made.4 Shigella organisms are able to bypass the gastric acid barrier and colonize the terminal ileum and colon. These organisms secrete proteins, which facilitate invasion of the intestinal epithelium. Mucosal invasion of the gut is associated with an intense inflammatory response resulting in mucosal edema with both PMN and mononuclear infiltration, leading to microabscess formation and mucosal ulcerations.8

S dysenteriae infections predominate within non-industrialized nations, and they can be particularly virulent. This species has been associated with large outbreaks of disease, especially in developing countries,11 and will often cause septicemia, especially in young infants. S dysenteriae is the species most associated with severe dehydration and electrolyte imbalances as well as renal, gastrointestinal, and neurologic complications. S dysenteriae, type 1, produces the Shiga toxin, which is capable of affecting renal epithelial cells and causing the hemolytic uremic syndrome (HUS).5 It is also associated with some less common complications such as toxic megacolon. Seizures have been reported in hospitalized children with Shigellosis with some degree of frequency.

Severe Shigella infection is one of the diarrheal diseases in which antimicrobials can be of benefit.5 Use of appropriate antibiotics can help reduce severity and duration of disease. However, the use of antimicrobials in bloody diarrhea relies on the health care provider’s knowledge of the relative frequency of pathogens in different areas of the world and the emerging resistance to antimicrobials.9 In many developing countries, there are little sensitivity data available to help in guiding antimicrobial therapy. Trimethoprim-sulfamethoxazole, nalidixic acid, and amoxicillin are inexpensive antibiotics widely available for use in the treatment of Shigella dysentery. Treatment of shigellosis, however, has become complicated by the emergence of strains resistant to these antibiotics.3,11 High-level resistance has been demonstrated among all Shigella species but varies according to geographic location. When available, susceptibility results should be used to guide therapy. Current guidelines recommend limiting treatment to more severe cases of Shigella infection and use of ceftriaxone or a fluoroquinolone when resistance to other antibiotics is suspected or confirmed. Although use of fluoroquinolones in children remains controversial, experience has shown that short courses of this antimicrobial class should still be considered for severe infections resistant to other antimicrobials.10

References

1. Ryan ET, et al. N Engl J Med. 2002;347(7):505-516.

2. Ryan ET, Kain KC. N Engl J Med. 2000;342(23): 1716-1725.

3. Flores A, et al. Am J Med Sci. 1998;316(6):379-384.

4. Prado V, et al. Ped Infect Dis J. 1999;18(6):500-505.

5. Lopez E, et al. Infect Dis Clinics N Am. 2000;14(1): 41-65.

6. Diemert D. Primary Care Clinics in Office Practice. 2002;29(4).

7. Castelli F, et al. J Travel Med. 2001;8:(Suppl 2):S26-S30.

8. Sansonetti PJ, Mounier J. Microb Patholog. 1987;3: 53-61.

9. Ashkenazi S, et al. Antimicrob Agents Chemother. 1995; 39:819-823.

10. Schaad UB. Ped Infect Dis J. 1992;11:1043-1046.

11. Guerin PJ, et al. Lancet. 2003;362:705-706.

Melissa Held, MD, is currently a fellow in Pediatric Infectious Diseases, Dept of Pediatrics, Yale School of Medicine.