Microcheck 245

Vibrios, Campylobacter jejuni, and enterobacteria account for most intestinal bacterial infections. Pathogenic mechanisms include attachment, toxin production, cell invasion, and destruction of microvilli. Gastroenteritis can be caused either by infectious microorganisms consumed with the food or by toxic products of microbial growth in food. Some microbial toxins alter the secretory function of cells in the small intestine without killing or visibly damaging them. Unsuspected human carriers can remain sources of enteric infections for many years. Most vaccines are of limited value because they induce little IgA production.

■ Explain how Vibrio cholerae causes cholera without apparent damage to the intestinal epithelium.

■ How does the epidemiology of Salmonella Typhi differ from that of most other S. enterica?

■ What is the leading cause of bacterial diarrhea in the United States? What is its source?

■ How would you devise a selective medium for Vibrio cholerae?

Table 24.10 Campylobacteriosis


Diarrhea, fever, abdominal cramps, nausea, vomiting, bloody stools

Incubation period

Usually 3 days (range, 1 to 5 days)

Causative agent

Campylobacter jejuni, a curved Gram-negative, microaerophilic rod


Low infecting dose.The bacteria multiply within and beneath the epithelial cells and incite an inflammatory response. Bloodstream invasion is uncommon. Complicated by a generalized paralysis, Guillain-Barre syndrome, on rare occasions


Large foodborne and waterborne outbreaks originating from chickens, cows and other animals. Person-to-person spread rarely occurs

Prevention and treatment

Water chlorination and pasteurization of beverages are effective control measures. Avoiding contamination of hands and food preparation areas with uncooked poultry, and cooking of poultry until it is no longer pink are also effective. Most victims recover within 10 days without antibacterial medications

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  • ghenet
    How v cholerae causes cholera without apparent damage to intestinal epithelium?
    3 years ago

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