Campylobacter

Spiral, gram-negative rods; may appear coccoid in older cultures. Generally heat-resistant, and are cultured at 42 degrees Celsius (note that Campylobacter upsaliensis is an exception). Grow in microaerobic conditions with relatively low oxygen levels and elevated carbon dioxide. Oxidase positive. Tiny, so they can be filtered from stool samples for diagnostic purposes. Vulnerable to stomach acids; thus, illness is most common in individuals with reduced stomach acid production. Zoonotic infections; that is, illness occurs after interactions with colonized animals. Lipo-oligosaccharide endotoxin. Polysaccharide capsule. Flagella facilitate motility and invasion of host cells. Cytolethal distending toxin is thought to cause cell death and IL-8 secretion. IL-8 is a pro-inflammatory cytokine that, when produced in excess, damages host tissues. Campylobacter species are the number one cause of bacterial gastroenteritis in the United States. Gastroenteritis is characterized by watery, sometimes bloody, diarrhea with blood cells present in the stools; some individuals have fever. Fortunately, the diarrhea is usually self-limited; illness lasts approximately six days. In severe cases, or where complications arise, erythromycin or azithromycin can be administered. Primary pathogenic species; infection is associated with consumption of contaminated poultry and cow products. Damages the mucosa of the jejunum, ileum, and colon: Villus ulceration (can become bloody) Neutrophils, eosinophils, and mononuclear cells invade the lamina propria Abscesses form in the glands and crypts. Infection can also cause bacteremia and cardiovascular dysfunction. Guillan-Barré syndrome is an autoimmune disorder that damages the myelin of the peripheral nervous system (hence it's a demyelinating disorder). Individuals typically experience symmetrical weakness that begins in the lower extremities; weakness may ascend, and, in severe cases, can impair cardiovascular and respiratory functioning due to autonomic system involvement. Blood pressure can swing wildly, so clinicians must be careful not to react too quickly to spikes in blood pressure or they can inadvertently cause devastating low blood pressures. Early treatment with IVIG or plasmapheresis is important in management but most important is good supportive care while the illness runs its course, meaning early intubation, if respiratory distress is identified, and good nursing care to avoid superimposed infections. Keys to diagnosing the disorder are: Hyporeflexia (from the peripheral neuropathy). CSF findings of cytoalbuminologic dissociation (meaning normal WBC but elevated protein) EMG findings that may be normal early on but later show prolonged F Waves, conduction block, and eventually the demyelination (prolonged distal latencies and conduction velocities). Acute Motor Axonal Neuropathy (AMAN) (GB variant, most common in China and Japan). This variant actually affects the axons, themselves, rather than simply disruption of the myelin-coating of the nerve – and thus will demonstrate as an axonopathy on EMG. Reactive arthritis is typically characterized by joint swelling and pain in the hands, knees, and ankles. Infection is associated with consumption of contaminated pork and poultry products. It primarily causes gastroenteritis, but is also associated with some extra-intestinal infections. An emerging pathogen associated with cats and dogs; thus, outbreaks have been traced to pet stores. It primarily causes gastroenteritis. Has been associated with Guillain-Barré syndrome. Infection primarily occurs in immunocompromised individuals. Resistant to serum killing by antibodies and complement, thanks to the presence of S protein, which prevents C3b binding. Bacteremia and septic thrombophlebitis (venous thrombosis with bacteremia) Endocarditis Meningoencephalitis Gastroenteritis