Stats on infection of cancer patients with Mycoplasmas
The numbers of cancer patients who are infected with these bacteria is unknown, but where reasonable studies have been carried out the results are frightening. A study from China by Su Huang (2001) published in the World Journal Gastroenterology, gave the results shown below.
Connection between Helicobacter pylori and gastric cancer
Another bacteria, Helicobacter pylori, has been much in the news lately. A Nobel Prize was won by researchers showing its role in the induction of stomach ulcers. This bacteria was classified as a human pathogen in 1994 by the International Agency for Research on Cancer (IARC). H. pylori has a positive association with gastric cancer. According to Correa (2003) more than half the world’s population is infected with H. pylori.
Early misclassification of Mycoplasmas and cell wall deficient forms
Viruses were distinguished from bacteria, particularly prior to 1940, based on their ability to pass through specific filters. Bacteria were larger so they were trapped by the filter, whereas viruses passed through. The size of the filters used at that time however allowed bacteria such as Mycoplasmas to easily pass through so they would have been mistakenly classified as viruses.
Recent work by Wainwright (2002) showed that the presence of the culture medium affected the ability of bacteria to pass through a 0.2 micron filter. When bacteria were given overnight incubation in a culture medium on the membrane, they formed small cell wall deficient forms that were able to pass through the filter. The bacteria that Wainwright used were all common human pathogens. This finding has significant repercussions for the field of microbiology and may indicate that studies carried out over the earlier part of the 20th century should be re-examined.
High incidence of infection in cancer
A 1997 paper by Pisani et al estimated that in 1990, 15.6% of the worldwide incidence of cancer could be attributed to infection with the Hepatitis B or C viruses, Helicobacter pylori, schistosomes or liver flukes. In developing countries the prevention of these infections would lower the cancer rate by 21%. The papilloma viruses are attributed with causing 89% of cancers of the cervix.
Salmonella infections linked to gall bladder cancer
Strong epidemiological evidence supports a link between infections with Salmonella typhi and gallbladder cancer. Carriers of S. typhi have 8.47 times the risk of gallbladder carcinoma compared with those who have had typhoid and have successfully cleared the infection (Lazcano-Ponce 2001, Welton 1979, Caygill 1994).
Chlamydophila pneumoniae in lung cancer
Chronic infections of Chlamydophila pneumoniae are now being found to correlate with an increased risk of lung cancer (Koyi 2001, Kocazeybek 2003, Anttila 2003). An elevated IgA antibody titre to C. pneumoniae has been reported to be associated with a 50% to 100% increased cancer risk (Littman 2004).