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Diagnosis can be accomplished by isolating bacteria from stool samples or vomitus and uneaten infected food. Treatment involves rehydration and supportive therapy. Antibiotics are not typically needed, as the illness is usually relatively mild and is due to toxin activity.

Foodborne illness due to Yersinia

The genus Yersinia is best known for Yersinia pestis , a gram-negative rod that causes the plague. However, Y. enterocolitica and Y. pseudotuberculosis can cause gastroenteritis . The infection is generally transmitted through the fecal-oral route, with ingestion of food or water that has been contaminated by feces. Intoxication can also result because of the activity of its endotoxin and exotoxins ( enterotoxin and cytotoxin necrotizing factor ). The illness is normally relatively mild and self-limiting. However, severe diarrhea and dysentery can develop in infants. In adults, the infection can spread and cause complications such as reactive arthritis, thyroid disorders, endocarditis, glomerulonephritis, eye inflammation, and/or erythema nodosum. Bacteremia may develop in rare cases.

Diagnosis is generally made by detecting the bacteria in stool samples. Samples may also be obtained from other tissues or body fluids. Treatment is usually supportive, including rehydration, without antibiotics. If bacteremia or other systemic disease is present, then antibiotics such as fluoroquinolones , aminoglycosides , doxycycline , and trimethoprim-sulfamethoxazole may be used. Recovery can take up to two weeks.

  • Compare and contrast foodborne illnesses due to B. cereus and Yersinia .

Bacterial infections of the gastrointestinal tract

Bacterial infections of the gastrointestinal tract generally occur when bacteria or bacterial toxins are ingested in contaminated food or water. Toxins and other virulence factors can produce gastrointestinal inflammation and general symptoms such as diarrhea and vomiting. Bacterial GI infections can vary widely in terms of severity and treatment. Some can be treated with antibiotics, but in other cases antibiotics may be ineffective in combating toxins or even counterproductive if they compromise the GI microbiota. [link] and [link] the key features of common bacterial GI infections.

Table titled: Bacterial Infections of the GI Tract. Columns: Disease, Pathogen, Signs and Symptoms, Transmission, Diagnostic Tests, Antimicrobial Drugs. Bacillus cereus infection, Bacillus cereus; Nausea, pain, abdominal cramps, diarrhea or vomiting ; Ingestion of contaminated rice or meat, even after cooking; Testing stool sample, vomitus, or uneaten food for presence of bacteria; None. Campylobacter jejuni gastroenteritis; Campylobacter jejuni; Fever, diarrhea, cramps, vomiting, and sometimes dysentery; sometimes more severe organ or autoimmune effects; Ingestion of unpasteurized milk, undercooked chicken, or contaminated water; Culture on selective medium with elevated temperature and low oxygen concentration; Generally none; erythromycin or ciprofloxacin if necessary. Cholera; Vibrio cholera; Severe diarrhea and fluid loss, potentially leading to shock, renal failure, and death; Ingestion of contaminated water or food; Culture on selective medium (TCBS agar); distinguished as oxidase positive with fermentative metabolisms; Generally none; tetracyclines, azithromycin, others if necessary. Clostridium difficile infection; Clostridium difficile; Pseudomembranous colitis, watery diarrhea, fever, abdominal pain, loss of appetite, dehydration; in severe cases, perforation of the colon, septicemia, shock, and death; Overgrowth of C. difficile in the normal microbiota due to antibiotic use; hospital-acquired infections in immunocompromised patients; Detection of toxin in stool, nucleic acid amplification tests (e.g., PCR); Discontinuation of previous antibiotic treatment; metronidazole or vancomycin. Clostridium perfringens gastroenteritis; Clostridium perfringens (especially type A); Mild cramps and diarrhea in most cases; in rare cases, hemorrhaging, vomiting, intestinal gangrene, and death; Ingestion of undercooked meats containing C. perfringens endospores; Detection of toxin or bacteria in stool or uneaten food; None. E. coli infection; ETEC, EPEC, EIEC, EHEC ; Watery diarrhea, dysentery, cramps, malaise, fever, chills, dehydration; in EHEC, possible severe complications such as hematolytic uremic syndrome; Ingestion of contaminated food or water; Tissue culture, immunochemical assays, PCR, gene probes; Not recommended for EIEC and EHEC; fluoroquinolones, doxycycline, rifaximin, and TMP/SMZ possible for ETEC and EPEC.
Table Titled: Bacterial Infections of the GI Tract (continued). Columns: Disease, Pathogen, Signs and Symptoms, Transmission, Diagnostic Tests, Antimicrobial Drugs. Peptic ulcers; Helicobacter pylori; Nausea, bloating, burping, lack of appetite, weight loss, perforation of stomach, blood in stools ; Normal flora, can also be acquired via saliva, Fecal-oral route via contaminated food and water; Breath test, detection of antibodies in blood, detection of bacteria in stool sample or stomach biopsy; Amoxicillin, clarithromycin metronidazole, tetracycline, lansoprazole; antacids may also be given in combination with antibiotics. Salmonellosis; Salmonella enterica, serotype Enteritides; Fever, nausea, vomiting, abdominal cramps, headache, diarrhea; can be fatal in infants; Ingestion of contaminated food, handling of eggshells or contaminated animals Culturing, serotyping and DNA fingerprinting ; Not generally recommended; fluoroquinolones, ampicillin, others for immunocompromised patients. Shigella dysentery; Shigella dysenteriae, S. flexneri, S. boydii, and S. sonnei; Abdominal cramps, fever, diarrhea, dysentery; possible complications: reactive arthritis and hemolytic uremic syndrome; Fecal-oral route via contaminated food and water; Testing of stool samples for presence of blood and leukocytes; culturing, PCR, immunoassay for S. dysenteriae; Ciprofloxacin, azithromycin. Staphylococcal food poisoning; Staphylococcus aureus; Rapid-onset nausea, diarrhea, vomiting lasting 24–48 hours; possible dehydration and change in blood pressure and heart rate;Ingestion of raw or undercooked meat or dairy products contaminated with staphylococcal enterotoxins; ELISA to detect enterotoxins in uneaten food, stool, or vomitus ; None. Typhoid fever; S. enterica, subtypes Typhi or Paratyphi Aches, headaches, nausea, lethargy, diarrhea or constipation, possible rash; lethal perforation of intestine can occur Fecal-oral route; may be spread by asymptomatic carriers; Culture of blood, stool, or bone marrow, serologic tests; PCR tests when available; Fluoroquinolones, ceftriaxone, azithromycin; preventive vaccine available.  Yersinia infection; Yersinia enterocolitica, Y. pseudotuberculosis; Generally mild diarrhea and abdominal cramps; in some cases, bacteremia can occur, leading to severe complications; Fecal-oral route, typically via contaminated food or water Testing stool samples, tissues, body fluids; Generally none; fluoroquinolones, aminoglycosides, others for systemic infections.

Part 2

At the hospital, Carli’s doctor began to think about possible causes of her severe gastrointestinal distress. One possibility was food poisoning, but no one else in her family was sick. The doctor asked about what Carli had eaten the previous day; her mother mentioned that she’d had eggs for lunch, and that they may have been a little undercooked. The doctor took a sample of Carli’s stool and sent it for laboratory testing as part of her workup. She suspected that Carli could have a case of bacterial or viral gastroenteritis, but she needed to know the cause in order to prescribe an appropriate treatment.

In the laboratory, technicians microscopically identified gram-negative bacilli in Carli’s stool sample. They also established a pure culture of the bacteria and analyzed it for antigens. This testing showed that the causative agent was Salmonella .

  • What should the doctor do now to treat Carli?

Jump to the next Clinical Focus box. Go back to the previous Clinical Focus box.

Key concepts and summary

  • Major causes of gastrointestinal illness include Salmonella spp., Staphylococcus spp., Helicobacter pylori , Clostridium perfringens , Clostridium difficile , Bacillus cereus , and Yersinia bacteria.
  • C. difficile is an important cause of hospital acquired infection.
  • Vibrio cholerae causes cholera , which can be a severe diarrheal illness.
  • Different strains of E. coli , including ETEC , EPEC , EIEC , and EHEC , cause different illnesses with varying degrees of severity.
  • H. pylori is associated with peptic ulcers .
  • Salmonella enterica serotypes can cause typhoid fever , a more severe illness than salmonellosis .
  • Rehydration and other supportive therapies are often used as general treatments.
  • Careful antibiotic use is required to reduce the risk of causing C. difficile infections and when treating antibiotic-resistant infections.

Fill in the blank

Antibiotic associated pseudomembranous colitis is caused by _________.

Clostridium difficile

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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