Chapters authored
Clinical Manifestations of the Epsilonproteobacteria (Helicobacter pylori)
Epsilonproteobacteria is a large group of Gram-negative curved or spiral microaerophilic rods, of which many are difficult to culture. Because this group of bacteria is not very well investigated, our knowledge about them is limited, and a great amount of research is still needed. At least two species are well-established human pathogens: Campylobacter jejuni/coli causing gastroenteritis and Helicobacter pylori causing gastric and extra-gastric manifestations. It is well accepted that H. pylori causes a chronic inflammation in the stomach and thereby causes H. pylori-associated gastritis, which may or may not be symptomatic. The association between H. pylori and peptic ulcers, MALT lymphomas, gastric cancer, idiopathic thrombocytopenic purpura, and unexplained iron-deficiency anemia (IDA) is strongly evidence based. On the other hand, pernicious (vitamin B12 deficiency) anemia, neuromyelitis optica, asthma, and Graves’ disease are less evidence based. H. pylori may also be associated with cardiovascular disease, pancreatitis, pancreatic cancer, obesity, diabetes mellitus type 2, Parkinson’s disease, liver diseases, and preeclampsia. H. pylori is thus involved in many gastric and extra-gastric manifestations either directly or indirectly by several proposed mechanisms including antigenic mimicry.
Part of the book: Helicobacter Pylori
Gastric Microbiota and Resistance to Antibiotics
Studies on gastric microbiota find several bacterial families and species in the stomach using molecular-based techniques. When biopsies are cultured, there may be growth of bacteria, pure culture of Helicobacter pylori, or no growth. When looking at the histological sections of corresponding biopsies no bacteria may be seen, except curved rods (H. pylori) adherent to the gastric epithelial cells. In a number of biopsies, several different bacteria are cultured with or without H. pylori. The non–H. pylori bacteria cultured are like the normal oral flora and may be contamination of the samples during endoscopy. In histological sections, these bacteria are seen above the mucin layer and not adherent to the epithelial cells confirming that it is contamination of the samples and can thus not be regarded as gastric microbiota. Therefore, the susceptibility of H. pylori to antibiotics is independent of coexisting bacterial flora. A review of H. pylori susceptibility to antibiotics in untreated and previous treated patients will be given including meta-analyses of H. pylori susceptibility to metronidazole (MTZ), clarithromycin, and levofloxacin. These data indicate that these antibiotics become more doubtful to use for primary therapy and should be banned for secondary therapy without susceptibility testing.
Part of the book: Helicobacter Pylori