Surgical sutures are known to potentiate the development of wound infection. The purpose of this study was to investigate whether the capability of bacteria to adhere to various types of sutures has a significant effect on their ability to cause infections. Bacterial adherence to sutures was quantitatively measured using radiolabeled bacteria. In vitro adherence assays revealed remarkable variations in the affinity of bacteria to the various sutures: nylon bound the least bacteria while bacterial adherence to braided sutures (silk, Ti-cron, Dexon) was five to eight folds higher. The degree of infection obtained in mice in the presence of different sutures nicely correlated with their adherence properties. The different removal rate of adherent bacteria (glutaraldehyde-fixed) from various sutures by the tissue factors in mice supports the hypothesis that bacterial adherence to suture materials plays a significant role in the induction of surgical infection. Our observation points out at the need for careful suture selection in contaminated wounds. The adherence properties of sutures should be considered in any future surgical suture design.

Guinea pig colonic epithelial cells released by treating sections of the colon with solutions containing EDTA, dithiothreitol, and citrate avidly adhered Shigella flexneri bacteria. Separation of the intestinal cells from nonbound bacteria was achieved by differential sedimentation on a Percoll gradient. Adherence of S. flexneri 3a was obtained from E. Romanowska, Po-land. Shigella strains were grown in Luria broth supplemented with 5 mM CaCl2 and 0.2% glucose. Cells were stored at -70°C as described (10). Their virulence was repeatedly tested by the guinea pig eye inoculation technique (21). One of the S. flexneri (lb) strains was used throughout these experiments. E. coli strains were grown in 1% peptone (Difco Laboratories, Detroit, Mich.) 0.5% yeast extract, and 0.5% NaCl.Preparation of radiolabeled bacteria. S. flexneri cells were inoculated in Luria broth supplemented with 0.5% glucose, 5 mM CaCl2, and 0.1 mCi of ["4C]glucose per ml (239 mCi/mmol; The Radiochemical Centre, Amersham, England) and incubated at 37°C overnight. The bacteria were harvested by centrifuga-1110 on August 1, 2020 by guest http://iai.asm.org/ Downloaded from on August 1, 2020 by guest http://iai.asm.org/ Downloaded from

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