Campylobacter jejuni Case File

Campylobacter jejuni Case File

Eugene C.Toy, MD, Cynthia Debord, PHD, Audrey Wanger, PHD, Gilbert Castro, PHD, James D. Kettering, PHD, Donald Briscoe, MD

CASE 4

A 19-year-old male college student presents to the student health department with abdominal pain, diarrhea, and fever. He says that his symptoms started a day ago. He has had 10 stools in the past day and has noted blood mixed in with the stool on several occasions. He usually eats at home but reports having eaten chicken in the college cafeteria 3 days ago. He has no history of gastrointestinal (GI) disease. On examination, he has a temperature of 37.8°C (100°F) and appears to be in pain. His abdomen has hyperactive bowel sounds and is diffusely tender but without rigidity, rebound tenderness, or guarding. A general surgeon is consulted and is considering the diagnosis of acute appendicitis versus bacterial gastroenteritis possibly related to the chicken eaten. A stool sample tests positive for blood and fecal leukocytes. Stool cultures are sent and are subsequently positive for a pathologic organism.

◆ What is the most likely pathologic organism?

◆ In what atmospheric environment does this organism grow?

ANSWERS TO CASE 4: Campylobacter jejuni

Summary: A 19-year-old man presents with a bacterial gastroenteritis that mimics appendicitis.

◆ Most likely etiology of this infection: Campylobacter jejuni

◆ Preferred atmospheric environment: Microaerophilic (presence of increased levels of carbon dioxide)

CLINICAL CORRELATION

More than 50 serotypes of C. jejuni have been identified based on heat labile (capsular and flagellar) antigens. Campylobacter jejuni is endemic worldwide, and most cases of infection are associated with eating poorly cooked chicken, although milk, water and other meats have also been implicated. Human-to-human transmission is rare. Campylobacter jejuni is one of the most frequent causes of bacterial diarrhea occurring most often in the summer or early fall. The incubation period is 1–3 days followed initially by symptoms of fever, malaise, and abdominal pain. Campylobacter jejuni can cause bloody diarrhea, mucosal inflammation, and bacteremia, suggesting that it is invasive to the lining of the intestine. Most cases of Campylobacter gastroenteritis is self-limited, with symptoms resolving within 7 days; however, relapses can occur in 5–10 percent of cases which are untreated.

Complications of Campylobacter gastroenteritis include pancreatitis, peritonitis, or more uncommonly arthritis, osteomyelitis, and sepsis. A serious postinfection sequelae of Campylobacter gastroenteritis is Guillain-Barré syndrome, an acute demyelinating disease. Antigenic similarities between the lipopolysaccharides on the surface of some serotypes of C. jejuni and myelin proteins are thought to be responsible for causing Guillain-Barré disease.

Other Campylobacter species such as C. coli also cause gastroenteritis, which is clinically indistinguishable from C. jejuni infection. Campylobacter fetus is primarily a cause of bacteremia, septic arthritis, peritonitis, abscesses, meningitis, and endocarditis in immunocompromised patients.

APPROACH TO SUSPECTED Campylobacter

INFECTION

Objectives

1. Know the characteristics, virulence factors, and preferred growth environments of C. jejuni.
2. Know the sources of infection with and mechanism of transmission of C. jejuni.

Definitions

Guillain-Barré syndrome: A demyelinating disease resulting from similarities between the host and the surface of the Campylobacter organism.

Fecal leukocytes: White blood cells present in the stool, which correlate loosely with the presence of an invasive pathogen.

DISCUSSION

Characteristics of Campylobacter

Campylobacter species are small motile, nonspore-forming, comma-shaped, gram-negative bacilli. Its motility is the result of a single flagellum located at one or both poles of the organism. Campylobacter does not grow in aerobic or anaerobic environments. It is microaerophilic, requiring 5–10 percent oxygen and high concentrations of carbon dioxide for growth. Campylobacter jejuni grows better at 42°C (107.6°F) than 37°C (98.6°F). Campylobacter jejuni multiplies more slowly than other enteric bacteria, making isolation difficult from stool samples unless selective media are used. When selective media are used, the colonies that grow tend to be gray, mucoid, and wet appearing. Its outer membrane contains lipopolysaccharides with endotoxic activity. Extracellular toxins with cytopathic activity have also been found; however, little is known regarding the pathogenesis of this organism and the role of these putative virulence factors in disease. The organisms are sensitive to decreased pH, so it is hypothesized that factors that neutralize gastric acid enhance the organisms chances for survival.

Diagnosis

The differential diagnosis of acute gastroenteritis would include Salmonella, Shigella, Yersinia, as well as Campylobacter. Because of the feature of abdominal pain and cramps, sometimes in the absence of diarrhea, Campylobacter gastroenteritis can be misdiagnosed as appendicitis or irritable bowel syndrome. The presence of bloody diarrhea may also suggest enterohemorrhagic Escherichia coli.

Definitive diagnosis would be made by culture of the stool and growth of Campylobacter. Campylobacter are more fastidious than most other causes of bacterial gastroenteritis and specimens should be transported to the laboratory in media such as Cary-Blair. Selective media such as campy blood agar or Skirrow medium, which includes antibiotics to inhibit the normal stool flora, allows for growth of Campylobacter within 48–72 hours. Presumptive identification can be made by growth of oxidase positive colonies on selective media at 42°C (107.6°F) after 48–72 hours with characteristic commashaped, small, gram-negative bacilli seen on Gram stain. Confirmation of identification of either C. jejuni or C. coli can be made by resistance to cephalothin and susceptibility to nalidixic acid antimicrobial disks. As a result of the fastidious nature of these pathogens, a commercial assay for detection of Campylobacter antigen in the stool is frequently used for diagnosis.

Treatment and Prevention

Most often C. jejuni infection is self-limited and does not require specific antimicrobial therapy. Supportive care, that is, hydration, is often the only treatment needed. If specific therapy is needed for severe disease, or infection in immunocompromised patients, erythromycin is the drug of choice, because of the recent increase in resistance to fluoroquinolones.

Prevention involves care in food preparation. Foods, especially chicken, should be completely cooked, and exposure to raw or undercooked chicken or unpasteurized milk should be limited, especially in pregnant women or immunocompromised persons.

COMPREHENSION QUESTIONS

[4.1] Which of the following are the special laboratory conditions needed to recover C. jejuni?

A. 37°C (98.6°F) aerobic on blood agar plates

B. 37°C (98.6°F) anaerobic on blood agar plates

C. 42°C (107.6°F) microaerophilic on Skirrow medium

D. 42°C (107.6°F) aerobic on Skirrow medium

[4.2] A 21-year-old woman presents to the emergency room with shortness of breath 2 weeks after recovering from a “stomach flu.” Physical exam reveals ascending muscle weakness that began in her toes. Cardiac irregularities are also notable. A review of the patient’s chart revealed that a bacterial stool culture 2 weeks earlier, during the patient’s “flu” episode, found comma-shaped organisms growing at 42°C (107.6°F). Which of the following pairs represents the causative agent of this patient’s flu and the postflu condition, respectively?

A. Campylobacter jejuni, Guillain-Barré syndrome

B. Clostridium botulinum, botulism

C. JC virus, progressive multifocal leukoencephalopathy (PML)

D. Poliovirus, poliomyelitis

[4.3] In a nonimmunocompromised patient with C. jejuni as the causative agent of their food poisoning, which of the following is the treatment most often required?

A. Metronidazole

B. Vancomycin

C. Cephalosporin

D. TMP-SMZ

E. Supportive care and hydration

[4.4] A 20-year-old college student develops diarrhea that lasts for approximately 1 week. Stool cultures reveal a motile, microaerophilic gramnegative rod that is isolated by incubation at 41°C (105.8°F) on medium containing antibiotics. This organism is most likely to be which of the following?

A. Escherichia coli

B. Vibrio parahaemolyticus

C. Yersinia enterocolitica

D. Campylobacter jejuni

E. Proteus vulgaris

Answers

[4.1] C. The isolation and identification of C. jejuni can be achieved using special culture characteristics. Three requirements must be met. First, a selective medium is needed. There are several widely used selective media: Skirrow’s medium uses vancomycin, polymyxin B, and trimethoprim; other selective media contain cefoperazone, other antimicrobials, and inhibitory compounds. The selective media are suitable for isolation of C. jejuni at 42ºC (107.6°F); when incubated at 36–37ºC (96.8–98.6°F), other Campylobacters and bacteria may be isolated. Finally, incubation must be in an atmosphere with reduced oxygen and added carbon dioxide. The colonies appear to be colorless or gray and may be watery and spreading or round and convex.

[4.2] A. Guillain-Barré syndrome (acute idiopathic polyneuritis) is associated with infections such as herpesvirus and C. jejuni (comma-shaped bacteria that grows at 42°C [107.6°F]). It is believed that some C. jejuni serotypes have surface lipopolysaccharides that are antigenically similar to myelin protein leading to the inflammation and demyelination of peripheral nerves and ventral root motor fibers. Suspected Guillain- Barré in a patient is always a medical emergency because respiratory distress or failure can ensue, and the patient should always be admitted to the hospital for careful treatment and observation. The other answers contain correct matching of the causative agent with the resulting condition, but do not reflect the clinical scenario described.

[4.3] E. Most infections with C. jejuni are self-limiting and thus do not require specific antimicrobial therapy, except in cases of severe disease and infection in immunocompromised individuals. Therefore, most often the only required therapy is hydration and supportive care. When specific antimicrobial therapy is indicated, the drug of first choice is erythromycin, with alternate drugs being tetracycline, ciprofloxacin, and ofloxacin.

[4.4] D. Based on the culture characteristics indicated above, the only possible answer is C. jejuni. Please also refer to the discussion for Question [4.1].

MICROBIOLOGY PEARLS ❖ Campylobacter species are small motile, non-spore-forming, commashaped, gram-negative bacilli, best grown in a microaerophilic environment at 42°C (107.6°F). ❖ Guillain-Barre is a rare neurological complication of C. jejuni gastroenteritis. ❖ Campylobacter jejuni gastroenteritis is usually self-limited; however, if necessary, erythromycin is the drug of choice. ❖ Campylobacter infection most often occurs several days after consumption of undercooked chicken. ❖ Symptom of fever and abdominal pain may initially mimic appendicitis.

REFERENCES

Allos BM. Campylobacter jejuni infections: update on emerging issues and trends. Clin Infect Dis 2001;32:1201–6. 

Murray PR, Rosenthal KS, Pfaller MA. Campylobacter and Helicobacter. In: Murray PR, Rosenthal KS, Pfaller MA. Medical Microbiology, 5th ed. St. Louis, MO: Mosby, 2005:347–55. 

Winn W, Allen S, Janda W, Koneman E, et al. Curved gram negative bacilli and oxidase-positive fermenters; Campylobacteraceae and Vibrionaceae in Koneman’s Color Atlas and Textbook of Diagnostic Microbiology, 6th ed., Baltimore, MD: Lippincott, Williams and Wilkins, 2006:392–428.

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