This is another reason you should be careful of who you sleep with and ALWAYS practice safe sex. Another woman has been diagnosed with a flesh eating STD. I'll save you the nasty details. But Donovanosis is an STD caused by a bacterium called Klebsiella granulomatis, according to the National Institutes of Health. The disease can start out as small, painless sores (ulcers) on the genitals. The sores get bigger and form big red bumps that bleed easily.