The photograph is of a modified fuchsin stain of organisms recovered from a stool culture obtained from a 1-year old Guatemalan girl suffering 3 days of diarrhea as a result of a Campylobacter infection. A smear of the cultured organism was stained with undiluted carbolfuschin Ziehl-Neelsen solution (Merck) for 3 minutes at room temperature.
Campylobacter species may be characterized by their rapidly darting motility when viewed microscopically using fresh samples or liquid cultures. Also, the characteristic morphology in a Gram stain, or better, in a modified fuchsin stain (described above), is very conspicuous, presenting as diverse “gull-winged,” spiral, and “S“-shaped forms noted by the arrows in the labeled view.
A stool sample was collected using a sterile cotton swab and sent to the laboratory in cold Cary-Blair transport medium. The sample was inoculated to Karmali medium and incubated at 42°C for 48 hours in a microaerophilic environment (CampyGEN, Oxoid). Colonies consistent with Campylobacter were determined to be curved gram-negative bacilli positive for oxidase. Additional tests were carried out to identify the species. The isolate was positive for catalase, sodium hippurate hydrolysis, and rapid darting motility. The specimen was negative for other enteric pathogens.
Several Campylobacter spp. have been implicated in human infection: C. fetus, C. jejuni, C. coli, C. sputorum, C. concisus, C. curvus, and C. rectus. Patients infected with C. jejuni present with a diarrheal disease that begins with mild abdominal pain within 2 to 10 days after ingestion of the organism. Cramps and bloody diarrhea often follow the initial symptoms. Patients may experience fever and chills and, rarely, nausea and vomiting. In most patients, the illness is self-limited and usually resolves in 2 to 6 days. Other enteric Campylobacter infections (i.e., those caused by C. coli and C. lari) have similar clinical manifestations.
Strong evidence suggests that Campylobacter infection plays a role in Guillain-Barré syndrome (GBS), an autoimmune disorder characterized by paralysis because of damage to the peripheral nervous system. Many patients with GBS test positive for antibodies to Campylobacter.
Isolates from stool samples on selective media can be presumptively identified as Campylobacter spp. by being oxidase positive and by showing the characteristic Gram stain morphology and motility. The microscopic morphology is very important because it differentiates Campylobacter from other oxidase-positive bacterial species (e.g., Aeromonas and Pseudomonas).
Oxidase-positive isolates which grow at 42°C in a microaerophilic environment should be suspended in brucella or tryptic soy broth to microscopically observe the typical motility. Distilled water and saline seem to inhibit motility. A positive hippurate hydrolysis reaction is an important biochemical test for the identification of C. jejuni.
For species identification, commonly used analyses include oxidase, catalase, growth at 42°C in a microaerophilic atmosphere (5% oxygen, 10% CO2, 85% nitrogen), the hydrolysis of sodium hippurate, susceptibility to nalidixic acid (30 ug), and resistance to cephalotin (30 ug).
References.
1. Feasby, T. E., and R. A. C. Hughes. 1998. Campylobacter jejuni antiganglioside antibodies and Guillain-Barré syndrome. Neurology 51:340–342.
2. Gini, G. 2007. Manual de procedimientos para la identificación de las bacterias con importancia clínica, ed. 3. F & G Publishers, Guatemala, Guatemala.
3. Mahon, C. R., et al. 2007. Textbook of diagnostic microbiology, 3rd ed. Saunders-Elsevier, St. Louis, MO.
4. Winer, J. B. 2001. Guillain Barre syndrome. J. Clin. Pathol. Mol. Pathol. 54:381–385.
5. Winn, W., et al. 2006. Koneman´s color atlas and textbook of medical microbiology, 6th ed. Lippincott Williams & Wilkins, Philadelphia, PA.
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