Helicobacter

First one discovered in 1983 by Drs. Barry Marshall and J. Robin Warren Originally classified as a Campylobacter 22 species have now been discovered The six that are associated with human disease are : H. pylori, H. cinaedi, H. fennellia, H. canadensis, H. canis, and H. pullorum Table 33-3

Physiology and Structure Gram(-) spiral Characterized by the 16s rRNA genes, fatty acids, and polar flagella on each end Have bacillary or spiral shape in young cultures but take on a coccoid shape in older cultures Requires microaerophilic environment with enriched medium agar and temperature must be between 30-37°C

Diseases Helicobacters are divided into two groups Table 33-3 –Gastric H. Pylori –Enteric Other five bacterium –All cause gastroenteritis –H. fennelliae and H. cinaedi have been isolated from homosexual men with proctitis, proctocolitis and enteritis –Most of these diseases are uncommon and rare

H. Pylori 50% of the world population is infected –70-90% in developing countries, usually before 10 years –Infections are much lower in the U.S. »About 45% of older adults are infected »More common in older adults, African Americans, Hispanics, and people with lower socioeconomic status Cause peptic ulcers, duodenal ulcers, acute and cronic gastritis –Associated with almost 100% of all gastritis infections –90% of duodenal ulcers, 80% of gastric ulcers –Persons with infection have a six fold greater chance of developing gastric cancer and MALT lymphoma

Transmission The actual mode of transmission is not yet known –CDC believes that it is by fecal-oral, or oral- oral routes –There have been incidents of transmission from contaminated endoscopes –A possible reservoir for H. pylori is contaminated water

Prevention and Control Wash hands Eat properly prepared food Drink clean water A vaccine is in development –Bacteria appears to help prevent gastroesophageal (acid) reflux disease adenocarcinomas of the lower esophagus, so there is a question of whether to treat people that are asymtommatic

Diagnosis Microscopy –Gold standard –Invasive test Urease Test –Breath analysis Antigen detection –Stool specimen Culture –Invasive procedure –Experienced microbiologists are more successful at culturing bacteria Serology –Dignostic test of choice

Virulence factors Urease Heat shock protein Acid-inhibitory protein Flagella, Adhesins, Mucanase, Phospholipases, Superoxide dismutase, Catalase, Vacuolationg Cytotoxin. –Table 33-4

Treatment Combination of antibiotics, H 2 pump inhibitor, and bismuth Triple therapies work better than double and longer use of the therapy help with the eradication FDA has eight different treatments

H.pylori images courtesy of Medical Microbiology, Patrick R. Murray, Elsevier Mosby, 2005, pg