Microbiology and Characteristics of H. pylori
Lyudmila Boyanova
from: Helicobacter pylori (Edited by: Lyudmila Boyanova). Caister Academic Press, U.K. (2011)
Abstract
H. pylori are Gram-negative spiral and microaerophilic bacteria that undergo coccoid transformation under hostile conditions. The coccoids and bacterial biofilms may participate in the transmission of infection. Specific H. pylori characteristics such as its enormous genomic diversity, helical morphology, acid acclimation, Krebs cycle and lipopolysaccharide indicate the extreme adaptation of the bacteria to the gastric mucosa. Modern methods such as comparative genomics, transcriptomics and proteomics provide a deep insight on H. pylori genomic diversity and its expression according to the severity of the disease. Methods to diagnose the infection are invasive e.g., rapid urease test (RUT), histology, culture and molecular methods or less invasive such as string test, or non-invasive such as serology, urea breath test (UBT), stool antigen test (SAT) and some molecular methods. Choice of the test depends on the test characteristics e.g., type, preparation, accuracy, protocol, cut-off, availability and price, and on many patient characteristics, which indicate the likelihood of the infection. Recently, non-invasive methods such as immunoproteomics, new SATs and improved UBT and SAT protocols have been reported. Significance of anti-CagA antibodies for the risk of severe diseases has been highlightened. For the same purpose, a new test for serum pepsinogens and anti-H. pylori antibodies has been introduced. Recent molecular methods have been implemented to detect H. pylori and its resistance to both macrolides and quinolones or to spot non-invasively clarithromycin resistance. Advances have been made also in the invasive methods. In vivo histology has been suggested and, importantly, an operating link for histological estimation of gastric cancer risk (OLGA staging) has been published. However, further studies are strongly required on important issues, among them are applications of the present, or development of new, non-invasive tests for detection of H. pylori resistance to antibiotics, improvement of test accuracy in specific patient groups, use of most reliable biomarkers for severe diseases and strategy for H. pylori screening and eradication read more ...
