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Chapter 24 : Helicobacter and Campylobacter
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Helicobacter and Campylobacter are related organisms that colonize and cause disease in the gastrointestinal tract. The genus Campylobacter was proposed in 1963 to differentiate Vibrio fetus from other less related Vibrio species. Campylobacter jejuni is a leading cause of bacterial gastroenteritis, a disease characterized by diarrhea, abdominal pain and fever. Treatment with erythromycin is effective early in the course of infection, and is currently considered the drug of choice for treating culture-confirmed cases. Metronidazole (Mtz) is a pro-drug and must be reduced in the stomach to a hydroxylamine derivative which damages DNA and appears to cause cell death by nicking DNA. Resistance to the fluoroquinolone ciprofloxacin (Cip) was acquired very rapidly by Helicobacter pylori isolates in a clinical trial in which ciprofloxacin was used to eradicate the microorganism. The associations of Cip resistance (Cipr) Campylobacter in humans to selection in the poultry production environment prompted the Food and Drug Administration to propose withdrawing approval of the new animal drug applications for use of the fluoroquinolones in poultry. Multidrug efflux pumps are also operative in Campylobacter and contribute to fluoroquinolone susceptibility. Remarkably, the two plasmids were 94.3% identical at DNA sequence level and are widespread in plasmid-containing, tetracycline resistance (Tcr) Campylobacter isolates. Campylobacter are generally resistant to trimethoprim and sulfonamides, through mechanisms common to other bacteria. While Campylobacter and Helicobacter have been recognized as human pathogens for over 100 years, only recent microbiological advances have made detailed study of these fastidious pathogens possible.