Abstract
In September 2005, the Sanitary Surveillance Service of Rio de Janeiro (SSS/RJ), Brazil, investigated a case of gastroenteritis involving a 13-year-old teenager hospitalized because of bloody diarrhea and severe abdominal pain. Owing to the severity of the symptoms, an epidemiological investigation was conducted in two states of Brazil. Escherichia coli O157:NM was isolated from stools and from a tomato and cheese salad prepared at the school canteen where the teenager attended. This is the first report of a human case of gastroenteritis related to E. coli O157:NM infection in Brazil.
Introduction
C
Until now, there have been no reports of human gastroenteritis involving E. coli O157:NM in Brazil. The isolation of this microorganism was only reported from calves with diarrhea (Guth et al., 2003). The aim of this study was to describe a case of human foodborne disease caused by E. coli O157:NM in Brazil.
Methodology
Notification and general investigation
A case of severe diarrhea was notified by telephone to the SSS/RJ and routine foodborne investigation was initiated according to OPAS/WHO (1978).
Microbiological testing
Stools and suspicious food samples were sent to the Reference Laboratory of Public Health of Rio de Janeiro Noel Nutels to be analyzed following methods described by FDA/CFSAN (2001).
The motility of typical colonies of E. coli O157 was evidenced by successively growing suspect isolates in semisolid agar according to Ewing (1986).
NM, indole-positive, and beta-glucuronidase-negative isolates were tested for agglutination with E. coli O157 antiserum at the Reference Laboratory of Enterobacteriaceae in Fundação Osvaldo Cruz–FIOCRUZ, following the method of Orskov and Orskov (1984). O157-positive isolates were further analyzed by tissue culture assay for Shiga-like toxins (FDA/CFSAN, 2001). Non-O157 STEC isolates were not investigated.
Results
Foodborne disease description
On September 13, 2005, a 13-year-old boy was hospitalized at the Pediatric Medical Center of Barra da Tijuca, Rio de Janeiro (RJ). Medical reports revealed intense abdominal pain and severe diarrhea. Computerized tomography and ultrasonography revealed mesenteric adenitis. Clinical symptoms evolved to bloody diarrhea, cramps, and one emetic episode. Intravenous antibiotic treatment was administered every 12 h (Rocefin; Roche). The patient returned home after 3 days in hospital. Coproculture was positive for E. coli O157:NM Shiga toxin-positive.
The patient expressed to have consumed different meals at the canteen of the school he attended in the city of Jacarepaguá, RJ, the week before the burden of symptoms. None of the other family members got sick even though they ate the same food at home or at restaurants as the patient.
Five days before getting sick, the patient participated in a school trip to the city of Tiradentes, State of Minas Gerais (from September 8 to 10, 2005). There, he had several meals at different restaurants. Teachers and students who were part of the trip were also interviewed to identify the possible consumption of foods commonly linked to transmission of E. coli O157. Among the 62 people who participated in the school trip, 58 (52 teenagers and 6 adults) were interviewed. Five teenagers described gastrointestinal symptoms after the trip. One of them reported intense watery diarrhea (nonbloody), fever, prostration, body pain, abdominal pain, and sore throat with oropharyngeal hyperemia lasting for 4 days. No nausea or vomit was reported and he was not hospitalized.
On September 16, 2005, the Sanitary Surveillance Service of the State of Minas Gerais sent a technical note and a sanitary alert informing about the foodborne case and the possible involvement of food establishments where the group had their meals during the trip to Minas Gerais to RJ. Official inspections were also carried out in the establishments of Minas Gerais. Sanitary officers did not find significant irregularities inside the food establishments. They then investigated the canteen where teenagers consumed meals before travel. Several foods were sampled and sent to the Reference Laboratory of Public Health of RJ. A tomato and Minas cheese salad showed rotten odor and counts of thermotolerant coliforms above the limit established by the Brazilian Microbiological Standard regulation (Brasil, 2001). Sampling was carried out 5 days after the development of symptoms and the analysis showed a Shiga toxin-negative E. coli O157:NM contamination. Based on these results, this salad was considered the most probable source of the infection. Additional sampling of Minas-type cheese was carried out at the supermarket where the cheese was purchased, but no E. coli O157:NM was isolated.
Discussion
This study describes a foodborne case caused by E. coli O157:NM in RJ, Brazil, in 2005. The case details were stored in the Surveillance Sanitary Service archive and were not available for publication. Only recently, with the increasing importance of E. coli O157 in Brazil, this information was made available for publication.
An interesting fact was that the E. coli O157:NM isolated from patient's feces was Shiga toxin-positive, whereas the strain isolated from the tomato salad did not produce Shiga toxin. Some possible explanations for this result are the loss of stx genes or the incapacity of expression of these genes outside of intestine.
Based on epidemiological information, laboratory results, and that at the time E. coli O157:NM was uncommon in foods/stools, and there were no reported human infections, SSS/RJ assumed that the foodborne disease was caused by E. coli O157:NM. To avoid new cases, officers carried out new inspections in the food establishments where the victim used to buy food. Furthermore, a discussion session was organized with students at the school, focusing on clinical symptoms and possible routes of contamination with E. coli O157. In addition, guidelines on food consumption during trips were sent to school.
Conclusion
This study reported the first human case of foodborne disease caused by E. coli O157:NM in Brazil. The isolation of this microorganism in a tomato and Minas-type cheese salad prepared where the victim had lunch 1 week before the burden of symptoms indicated that the source of contamination was the school canteen where the victim studied.
Footnotes
Disclosure Statement
No competing financial interests exist.