Transmission of the infection probably occurs in multiple pathways, which may differ in different societies and age groups. As childhood is a period of high risk for H. pylori acquisition, a good understanding of the mode(s) of transmission in children is required to identify how to break the chain of transmission of the infection (77).
The minimum infectious dose of H. pylori for humans is not yet established.
In human volunteers, ingestion of 104–1010 of H. pylori after administration of famotidine resulted in infection in 18 out of 20 subjects (77). For non-human primates, the established minimum infectious dose of H. pylori is 104 cfu (68).
The most important reservoir of H. pylori is the human stomach; and potentially, H. pylori may pass …show more content…
The fastidious nature of H. pylori and the complexity of the oral microflora make the isolation of the microorganism from the oral cavity complicated. Most reports about presence of H. pylori in the oral cavity are based on detection of a specific DNA, which has been found in the dental plaque (98), in the periodontal pockets, and in the saliva. The detection rate, though, has shown a great deal of variation,
30
from less than 10% among the subjects harboring the organism in …show more content…
pylori-status (98).
A major weakness of PCR is its inability to distinguish between viable or dead microorganisms, and therefore, detection of the DNA of the microorganism in the oral cavity is not sufficient evidence for considering it a reservoir of the infection (77). Although successful culture of H. pylori from the oral cavity has also been reported, the success rate is low (97). The number of organisms in the oral cavity, if present, is rather small: using a competitive PCR assay the median number of H. pylori in dental plaque of adults with gastric H. pylori infection was found to be 25 cells/mg ; in the postemesis saliva collected half an hour after vomiting H. pylori cultures had counts ranging from 50–500 cfu/ml (97). Some epidemiological results also favor spread of H. pylori by an oral source. Pre-mastication of food and plate sharing were found to be independent risk factors for H. pylori infection of children (77).
2.2.4.3 Environmental sources: water and food
The analysis of the genome has shown that it is very unlikely that H. pylori can multiply in environment. H. pylori can survive in water, milk and
The minimum infectious dose of H. pylori for humans is not yet established.
In human volunteers, ingestion of 104–1010 of H. pylori after administration of famotidine resulted in infection in 18 out of 20 subjects (77). For non-human primates, the established minimum infectious dose of H. pylori is 104 cfu (68).
The most important reservoir of H. pylori is the human stomach; and potentially, H. pylori may pass …show more content…
The fastidious nature of H. pylori and the complexity of the oral microflora make the isolation of the microorganism from the oral cavity complicated. Most reports about presence of H. pylori in the oral cavity are based on detection of a specific DNA, which has been found in the dental plaque (98), in the periodontal pockets, and in the saliva. The detection rate, though, has shown a great deal of variation,
30
from less than 10% among the subjects harboring the organism in …show more content…
pylori-status (98).
A major weakness of PCR is its inability to distinguish between viable or dead microorganisms, and therefore, detection of the DNA of the microorganism in the oral cavity is not sufficient evidence for considering it a reservoir of the infection (77). Although successful culture of H. pylori from the oral cavity has also been reported, the success rate is low (97). The number of organisms in the oral cavity, if present, is rather small: using a competitive PCR assay the median number of H. pylori in dental plaque of adults with gastric H. pylori infection was found to be 25 cells/mg ; in the postemesis saliva collected half an hour after vomiting H. pylori cultures had counts ranging from 50–500 cfu/ml (97). Some epidemiological results also favor spread of H. pylori by an oral source. Pre-mastication of food and plate sharing were found to be independent risk factors for H. pylori infection of children (77).
2.2.4.3 Environmental sources: water and food
The analysis of the genome has shown that it is very unlikely that H. pylori can multiply in environment. H. pylori can survive in water, milk and