Journal of Methods Microbiological Journal of Microbiological Methods 39 (2000) 265–270 www.elsevier.com / locate / jmicmeth Use of macroporous polypropylene filter to allow identification of bacteria by PCR in human fecal samples a a a Aldo Cavallini ScD , Maria Notarnicola ScD , Pasquale Berloco ScD , b a, * Antonio Lippolis ScD , Alfredo Di Leo MD, PhD a Laboratory of Biochemistry, I.R.C.C.S. «S. de Bellis», Scientific Institute for Digestive Diseases, Via Della Resistenza, 70013 Castellana Grotte ( BA), Italy b Laboratory of Clinical Pathology, I.R.C.C.S. «S. de Bellis», Scientific Institute for Digestive Diseases, Via Della Resistenza, 70013 Castellana Grotte ( BA), Italy Received 12 July 1999; received in revised form 20 October 1999; accepted 23 October 1999 Abstract The detection of pathogenic bacteria directly in human fecal specimens by PCR, requires removal of PCR-inhibitory substances. To investigate whether five different macroporous filters (polypropylene, nylon, polyester, polyethylene, fluorocarbon) could retain polysaccharides, major PCR inhibitors, an in vitro model and human fecal samples were used. The in vitro model consisted of Xanthum gum solutions (3 mg / ml PBS), a bacterial polysaccharide, to which Helicobacter pylori cells were added. Fecal samples from healthy volunteers were spiked with H. pylori and Mycobacterium paratuberculosis cells. Polysaccharide concentrations were significantly reduced only by the polypropylene but not by the other filters. Accordingly, both Xanthum gum solutions and spiked fecal specimens became PCR positive only after filtration with the polypropylene filter. We conclude that this filter can be used to prepare a bacterial DNA template suitable for PCR analysis from human feces.  2000 Elsevier Science B.V. All rights reserved. Keywords: Feces; PCR inhibitors; Polypropylene filter; Polysaccharides. 1. Introduction Many techniques for DNA or RNA purification have been reported in the literature (Wilde et al., Although polymerase chain reaction (PCR) is 1990; Michaels et al., 1994; Chan and Goodwin, considered a valid and sensitive tool for diagnostic 1995; Chomczynski and Mackey, 1995; Deuter et al., purposes, this application has not been entirely 1995; Millar et al., 1995; Nollau et al., 1996; successful with human fecal samples. In fact, these Uwatoko et al., 1996; Debrot and Lee, 1997; Mac- samples can easily give false-negative results due to Farlane and Dahle, 1997; Ali et al., 1998) with the presence of a variety of fecal chemical com- special reference to bacterial DNA purification from pounds able to inhibit the polymerase reaction. human fecal samples with organic solvents or the combined action of high-salt concentration and chro- matography-based methods (Kato et al., 1993; van Zwet et al., 1994; Makristathis et al., 1998). Another *Corresponding author. technique involves the capture of specific bacteria by 0167-7012 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0167-7012(99)00122-0