Introduction and Objectives: The etiology of NIH type III (non-bacterial) prostatitis is undetermined. The concept that an undocumented bacterial infection may be contributing to this form of prostatitis is widely held. Culturing techniques to identify bacteria have been used for over 100 years, yet most microbial organisms remain difficult or impossible to culture. With the advent of molecular biology techniques to identify the bacterial genotype rather than the phenotype, it is now possible to detect any microorganisms, even those that are impossible to culture. We have applied the new molecular biology methods to determine the types of bacteria present in men with and without Type III prostatitis.
Methods: Semen and urine (VB1, VB2 and VB3) samples from men with (23) and without (8) prostatitis were centrifuged, and then the pellet was washed twice with PCR buffer. The pellet was lysed with a Proteinase K based lysis buffer. PCR, using universal Eubacterial primers, was performed on an aliquot of the lysed pellet: the resulting amplicons were electrophoresed and UV fluorescence was used to identify amplicons of the correct length. The cleaned amplicons were then cloned and sequenced. These sequences were compared to bacterial sequences on deposit in the ribosomal database (Urbana, Illinois) using a BLAST search.
Results: All semen and 47/58 urine specimens tested had bacterial DNA identified using universal Eubacterial PCR primers. A number of unusual organisms were identified in the urine and semen including Paenibacillus sp., Proteobacterium sp., Flavobacterium, uncultured eubacterium and Bradyrhizobium sp. The most frequently identified bacteria were of the Paenibacillus and Proteobacterium genera. These two genera were much more commonly found in men with prostatitis than in the controls.
Conclusions: This is the first reported finding of Paenibacillus sp. or Proteobacterium sp. in the human genitourinary tract fluids. What is surprising is that these two previously undetected species are the most common bacteria found in men with prostatitis. In addition, there is a clear preponderance of these bacterial genera in the semen and urine of men with Type III prostatitis compared to asymptomatic controls. This suggests that these bacteria are associated with prostatitis: this association could be causative or it could be that the prostatic microenvironment in men with prostatitis is conducive to growth of these particular organisms.