POLYMERASE-CHAIN-REACTION AMPLIFICATION OF BACTERIAL 16S RIBOSOMAL-RNA GENES FROM COLD-CUP BIOPSY FORCEPS

Purpose: In looking for a possible infectious cause for interstitial c ystitis (IC), we previously determined that bladder tissue specimens f rom both IC patients and controls were uniformly positive by polymeras e chain reaction assay (PCR) for bacterial 16S ribosomal RNA genes fro m various genera including Escherichia, Propionobacterium, Acinetobact er, and Salmonella. We therefore determined whether the biopsy forceps might be contaminated with bacterial DNA. Materials and Methods: A to tal of 23 samples were obtained following disinfection of 6 cold-cup b ladder biopsy forceps (2 to 5 specimens from each forceps over a perio d of 19 months). DNA was extracted from each sample, and PCR performed using nested primers from a highly conserved region of the bacterial 16S rRNA gene. Amplified DNA was purified and sequenced, and the seque nces obtained were compared with bacterial rRNA gene sequences recorde d in GenBank. Results: Thirteen of 23 forceps specimens were positive by PCR for bacterial DNA, including at least one rinse from each of th e 6 forceps. In comparison,none of 9 negative control specimens (steri le distilled water put into tubes and processed in the same manner as forceps rinses) had detectable bacterial DNA. Sequence data indicated the presence of a predominant organism in 12 of the 13 positive specim ens, with > 95% homology to DNA from several different genera of bacte ria including Escherichia, Propionobacterium, Stenotrophomonas and Pse udomonas. Conclusions: These data indicate that reusable bladder biops y forceps are frequently contaminated with bacterial DNA. Tissue speci mens procured with such instruments therefore are inappropriate source s to look for the presence of bacterial pathogens by PCR.