Vomiting and Diarrhea after a School Picnic

 Vomiting and Diarrhea after a School Picnic

 PATIENT HISTORY

   A 14-year-old male presented to his pediatrician for evaluation of vomiting,abdominal discomfort, and nonbloody diarrhea. Three days prior, he attended his school picnic, where he ate everything offered: barbecued chicken, potato salad, baked beans, tossed salad, and ice cream . Within 36 h of the picnic he noted mild abdominal discomfort, intermittent crampy abdominal pain, and three to five loose, watery bowel movements per day. He reported no blood in the stool, rash, pain on urination (dysuria), or blood in the urine (hematuria) and had no travel history, had no pets, and denied taking antibiotics. The school reports that at least 50 other students who attended the picnic are also reporting similar symptoms. 

LABORATORY TESTS

There are various interpretations of what is considered medically indicated for evaluating persons with acute diarrhea. Because most diarrheal illness is self-limited, the usefulness of stool cultures is questioned by some; however, early diagnosis can lead to interventions that both alleviate symptoms and prevent secondary transmission, which can have tremendous public health impact. In addition, detection of specific agents aids in the timely detection and control of outbreaks. Some causes of acute diarrhea can result in serious long-term sequelae such as Guillain–Barr´e syndrome (with

Campylobacter) or hemolytic uremic syndrome (HUS) due to EHEC, further justifying the need for performing stool culture. A stool specimen for culture should be obtained as early in the course of the disease as possible from all patients with bloody diarrhea, patients with fever, in persons with diarrhea who are immunosuppressed, from patients in whom the diagnosis of HUS is suspected, and from persons involved in possible outbreaks.

Pathogenic bacteria can be identified by isolating the organism by

culture and/or by identifying a characteristic marker for virulence such

as a toxin. Routine bacterial stool cultures can identify Campylobacter, Salmonella, Shigella,Yersinia enterocolitica, Aeromonas hydrophila, Pleisiomonas  shigelloides, and noncholera Vibrio spp. Special media are required to identify E. coli O157:H7 and Vibrio cholera, and laboratory personnel should be notified when such agents are suspected. In addition to culture, E. coli

O157:H7 can also be diagnosed using a toxin assay that detects shiga toxins produced by all EHEC types. Toxin assays rather than culture are routinely used for diagnosing Clostridium difficile diarrhea.

Because an outbreak was suspected from the school picnic our case

patient attended, a stool culture was performed despite the fact that he had a mild self-limited illness. A routine bacterial stool culture would be appropriate in this case since Salmonella, Shigella, or Campylobacter spp. would be the most likely causes. His lack of bloody diarrhea would make EHEC, such as E. coli O157:H7, less likely. His lack of travel history indicates that his specimen does not need to be screened for organisms found outside his geographic area, and the absence of antibiotic use makes testing for toxins of C. difficile less of a priority.

Because there is no specific antiviral treatment available, testing for viral causes of gastroenteritis is not routinely performed except in outbreak situations or hospital settings. Testing for rotavirus, a major cause of fever, vomiting, and watery diarrhea in infants and young children, is routinely performed in hospitals so that patients can be cohorted and infection control practices emphasized. Rotavirus is commonly seen during the winter months (October–March).

Feces should be submitted in a clean, dry, plastic or waxed cardboard container with a tight-fitting or screwcap lid. Once collected, the specimen can be maintained at room temperature during transport. Rectal swabs should be used only with infants and young children fromwhomcollecting feces may be difficult and again should be taken only during acute disease. For an adequate specimen, the swab should be inserted past the anal sphincter into the rectum, and feces should be obvious on the swab when

removed. If the specimen (feces or swab) will not be processed or reach the laboratory within 1 h, an enteric transport medium should be inoculated with the feces and this will be stable for as long as 72 h at room temperature. In addition to stool, blood cultures should also be obtained from patients who have fever and diarrhea.

 TREATMENT AND PREVENTION

 The first line of therapy is supportive treatment, to return the patient to fluid and electrolyte balance. The patient may drink an oral rehydration solution that contains water, salt, and sugar, or liquids such as Pedialyte, which have the appropriate electrolytes and fluids to replace those being lost. Most cases of gastroenteritis are self-limited and require no antibiotic therapy. In fact, antibiotics are contraindicated in some cases. Giving antibiotics for Salmonella gastroenteritis prolongs the carriage of the organism in the GI tract and can lead to the person retaining the organism for months. Treatment of E. coli O157:H7 may increase the risk of hemolytic

uremic syndrome (HUS) in children and should be avoided. Likewise, one should avoid using antimotility agents in cases with bloody diarrhea or proven EHEC infection.

Patients who are very young or immunosuppressed may require antibiotics to recover from their disease. Patients with Shigella gastroenteritis are more likely to be sicker and require antibiotic therapy than are patients with Salmonella or Campylobacter gastroenteritis. Ampicillin, SXT, or ciprofloxacin are common choices for antimicrobial therapy because they can be administered orally if the patient can tolerate drinking liquids. Since the organism may be resistant to one or more of these antimicrobials, susceptibility results for the patient’s organism should guide the physician’s choice.

According to surveillance by the Centers for Disease Control and Prevention (CDC), Campylobacter jejuni is the most common enteric pathogen seen in adult patients with diarrhea, whereas Salmonella is the most common in children. Campylobacter spp. are not susceptible to penicillins or cephalosporins. Ciprofloxacin and erythromycin are the drugs of choice.

If a patient is hospitalized with enteric fever (S. typhi), a thirdgeneration cephalosporin is usually given intravenously. Our case patient has an infection with Salmonella susceptible to ampicillin, SXT, and ciprofloxacin. Because he is a healthy young adult, only supportive treatment

was given.