Bacteria that become cell wall deficient have the ability to make enormous changes in their appearance. They have the following characteristics:
* They may disintegrate totally if fixed on a slide by heating (the standard method of fixing).
* They usually grow on soft agar.
* They may grow within red blood cells.
* They are often serophilic.
* They often grow best in a hypertonic environment (Boca Raton 1997).
Late 20th century: Mycoplasmas in Gulf War Syndrome patients
The end of the 20th century saw renewed interest in the investigation of Mycoplasmas. Mycoplasmas are of the class Mollicutes and are the smallest of the bacterial forms. Unlike other species of bacteria Mycoplasmas are unable to make cell wall components. They do not enter a cell wall deficient stage but they share many of the characteristics of the cell wall deficients (Boca Raton 1997). The work of Professor Garth Nicolson on the diagnosis and treatment of Gulf War Syndrome patients showed the pathogenicity of Mycoplasma infection. Infections of Mycoplasma pneumoniae were identified through antibody testing. Today the polymerase chain reaction (PCR) test is considered the gold standard for identification of such organisms.
Mycoplasmas inducing chromosomal instability and malignancy
Researchers at the American Registry of Pathology at the Armed Forces Institute of Pathology, Washington, have shown that chronic infection or colonisation by some Mycoplasmas in cell lines induced chromosomal instability and malignant transformation.
Their hypothesis was that chronic infection could promote tumour growth of mammalian cells. They also showed that infection by several, but not all species of Mycoplasma would prevent murine myeloid cells from undergoing apoptosis, and that these Mycoplasma infected cells gradually underwent malignant transformation over a period of four to five weeks. The two Mycoplasma strains used in this study were M. fermentans and M. penetrans (Lo 1999).
Affinity of Mycoplasmas for cancer cells
One the most fascinating characteristics of the Mycoplasmas is their affinity for cancer cells. All scientists working with cancer cell lines must continually check for Mycoplasma infection, and many papers are devoted to studies of how to eliminate Mycoplasmas from these cells (Uphoff 2002).
Why these particular species are the most likely contaminants of cancer cells does not yet appear to be answered. Testing for contamination is now recommended, by DNA fingerprinting or cytogenetic analysis, as the effect of Mycoplasmas in the cell lines may render research data highly unpredictable and questionable (Drexler 2002). Much research performed prior to DNA technology, (utilising cell lines) should be repeated with attention to possible infiltration of the cell lines by Mycoplasmas in order to verify the published outcomes of the studies.