Enterococcus faecalis can appear in your prostate fluid cause of many reasons:
1.chronic infection in urethra (urinary tract at all)
2.sex with no condom ( anal sex - very bad habit with no protection ,oral sex - it is too much bacterias in human mouth too, so you have to ( if you dont want to know what is - std and acute or chornic prostatitis is etc.) use condom in oral sex too
may be you will enjoy a little bit less, but you will enjoy much much more having "clean" urinary tract.
3. bad immunity .
Any way ,you should take antibiotic that treat Enterococcus faecalis and make prostate fluid culture test
again - after you finish taking medication.