Mycoplasma genitalium (sometimes called Mgen) is a bacterial infection spread through sexual contact. Although it's pretty common now, it isn't diagnosed and treated as often as it should be.
For those in the USA, find HIV and STD testing centers near you, as well as sites to receive vaccines for certain STDs. Site also provides information about HIV and STDs and can help guide your testing decisions.
There are instances in which condom use alone - or the use of dental dams and gloves -- cannot offer the level of STI protection they can in other instances, with STIs which are transmitted not via fluid exchange, but by skin-to-skin contact: namely two of the most common STIs, HPV and Herpes.
Whether you are with a new partner, or are already in a sexual relationship, getting a full STI screening can give you peace of mind and ensure your physical well-being as well as your partners.