Purpose: Several characteristics of the chronic bladder disease called interstitial cystitis (IC) suggest an infectious etiology. However, a single causative organism has not been convincingly cultured in vitro, and DNA for a variety of microorganisms has been found inconsistently in bladder biopsies from IC patients. We therefore looked for a possible bacterial cause for IC by using a sensitive nested PCR assay on cystoscopic bladder biopsy specimens obtained from IC patients and controls.

Materials and methods: Bladder biopsies were obtained at cystoscopy from 6 IC patients and 6 controls. DNA was extracted from these specimens and PCR with 2-round amplification performed using nested primers from a highly conserved region of the bacterial 16s rRNA gene. Amplified DNA was purified and sequenced using the Sequenase PCR Product Sequencing Kit, and the sequences obtained were compared with bacterial rRNA gene sequences recorded in GenBank.

Results: Biopsy specimens from all 6 patients and 6 controls were positive by PCR for DNA encoding bacterial 16s rRNA. Sequence data indicated a predominant microorganism in 10 of the 12 specimens, with > 95% homology to DNA from several different genera of bacteria including Acinetobacter, Propionobacterium, Salmonella, and Escherichia. None of the organisms identified by PCR had been cultured from tissue or urine obtained simultaneously from these persons, using sensitive culture techniques.

Conclusions: These data indicate no difference between IC patients and controls in the proportion of bladder biopsies with PCR positivity or the type(s) of organism present, providing additional evidence that IC is not associated with infection by a particular type of bacterium.