Mycoplasma genitalium promotes epithelial crossing and peripheral blood mononuclear cell infection by HIV-1.

BACKGROUND: Mycoplasma genitalium co-infection in HIV-infected individuals has been reported to increase the shedding of HIV in the urogenital region of females. To better understand this relationship, we investigated the influence of M. genitalium on the transmission and replication of HIV using an in vitro model. METHODS: The Transwell co-culture system was employed to assess the crossing of an endocervical cell barrier by HIV-1. Immunocytochemistry and confocal microscopy were used to assess the distribution of the nectin-1 molecule on M. genitalium-infected epithelial cells of the End1/E6E7 endocervical cell line, grown as monolayers in the insert wells. Peripheral blood mononuclear cells (PBMC) were cultured in the bottom wells to assess the effects of M. genitalium, passing through the semipermeable culturing membrane, on subsequent HIV infection of susceptible target cells. RESULTS: Infection of the endocervical cells with the adhesion-positive M. genitalium G37 strain (wild-type) significantly elevated the passage of HIV across the epithelial cell barrier relative to HIV transfer across endocervical cells infected with the adhesion-negative M. genitalium JB1 strain. Immunostaining of the M. genitalium-G37-infected epithelial cells disclosed capping and internalization of the junctional regulatory protein nectin-1, in association with reduced transepithelial resistance (TER) in the cell monolayer. When PBMC were cultured beneath insert wells containing M. genitalium-G37-infected epithelial cell monolayers, we observed significantly enhanced infectivity and replication of HIV added afterward to the cultures. CONCLUSIONS: M. genitalium influences events on both sides of a cultured mucosal epithelial monolayer: (1) by infecting the epithelial cells and reducing the integrity of the barrier itself, and (2) by activating HIV target cells below it, thereby promoting HIV infection and progeny virus production.

Methionine sulfoxide reductase A (MsrA) deficient Mycoplasma genitalium shows decreased interactions with host cells.

Mycoplasma genitalium is an important sexually transmitted pathogen that affects both men and women. In genital-mucosal tissues, it initiates colonization of epithelial cells by attaching itself to host cells via several identified bacterial ligands and host cell surface receptors. We have previously shown that a mutant form of M. genitalium lacking methionine sulfoxide reductase A (MsrA), an antioxidant enzyme which converts oxidized methionine (Met(O)) into methionine (Met), shows decreased viability in infected animals. To gain more insights into the mechanisms by which MsrA controls M. genitalium virulence, we compared the wild-type M. genitalium strain (G37) with an msrA mutant (MS5) strain for their ability to interact with target cervical epithelial cell lines (HeLa and C33A) and THP-1 monocytic cells. Infection of epithelial cell lines with both strains revealed that MS5 was less cytotoxic to HeLa and C33A cell lines than the G37 strain. Also, the MS5 strain was more susceptible to phagocytosis by THP-1 cells than wild type strain (G37). Further, MS5 was less able to induce aggregation and differentiation in THP-1 cells than the wild type strain, as determined by carboxyfluorescein diacetate succinimidyl ester (CFSE) labeling of the cells, followed by counting of cells attached to the culture dish using image analysis. Finally, MS5 was observed to induce less proinflammatory cytokine TNF-α by THP-1 cells than wild type G37 strain. These results indicate that MsrA affects the virulence properties of M. genitalium by modulating its interaction with host cells.

An exploratory study of methicillin-resistant Staphylococcus aureus and SCCmec elements obtained from a community setting along the Texas border with Mexico.

An exploratory study of methicillin-resistant Staphylococcus aureus (MRSA) and SCCmec elements in bacteria along the Mexican border of south Texas was performed. Between September and December of 2008, 375 swabs of anterior nares were self-collected by students attending the University of Texas-Pan American (UTPA) and cultured for MRSA. Fifty seven bacterial isolates were kept for further analysis that included suspected MRSA and other SCCmec-containing bacteria. Isolates were examined for the presence of nuc, mecA, lukS-PV, and spa genes using PCR. SCCmec and spa typing were also performed. Seven S. aureus isolates were found of which six were classified as MRSA. SCCmec typing showed five of the six MRSA strains to be type IV, while one MRSA strain, and most of the non-S. aureus strains, were untypeable, producing results that were indicative of mixed SCCmec types. Five of the six MRSA strains contained known spa types (two of which corresponded to USA300 and one to USA600), while one strain had a novel spa type. Only one isolate, a USA300 MRSA, was positive for lukS-PV. Easy access by the Texas border community to antibiotics in Mexico without a prescription, and the strong partition in SCCmec types between MRSA and non-S. aureus bacteria suggest that this border region of Texas may be uniquely suited for the study of emerging SCCmec types, their horizontal transfer, and perhaps other aspects of antibiotic resistance in bacteria.