Since the discovery in 1991 of the bacterium M. penetrans in immunocompromised patients, including HIV-positive patients, this organism has been described as a potential cofactor in AIDS, helping advance the progression of the disease (Lo et al., 1992, 1993), and unlikely to be able to infect immunocompetent individuals. However, the recent detection of M. penetrans DNA in multiple non-immunocompromised patients with non-gonococcal urethritis (D. Nelson, Indiana University School of Medicine, personal communication) has the potential to completely change the conception that this organism is restricted to immunocompromised patients, suggesting that it is a frank human pathogen. The mechanisms M. penetrans uses to survive during an infection and cause disease are unknown, although it has several features associated with virulence in other mycoplasma species. One is a polar attachment organelle, constructed using an unusual set of cytoskeletal proteins, that confers adherence to host cells and surfaces, and facilitates unidirectional gliding motility along surfaces (Jurkovic et al., 2012; Distelhorst et al., 2017). Another feature potentially associated with virulence is a potential ADP-ribosylating toxin (Johnson et al., 2009). Finally, M. penetrans produces hydrogen peroxide (Pritchard and Balish, unpublished data) and likely produces hydrogen sulfide (Grosshennig et al., 2016), two molecules associated with virulence in other mycoplasma species. We hypothesize that the M. penetrans strains associated with disease in these recently discovered cases of immunocompetent individuals have virulence-associated properties that are distinct from those found in immunocompromised people. This research has further prepared me for a future medical profession by promoting critical thinking and troubleshooting experimental design.
Author: Esha Chadha
Faculty Advisors: Mitchell F. Balish and Nathan R. Schwab, Department of Microbiology
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