Examination of the morphology of bacteria adhering to peritoneal dialysis catheters by scanning and transmission electron microscopy

Abstract

We examined Tenckhoff peritoneal catheters by scanning and transmission electron microscopy to study the morphology of bacterial adherence. Two catheters were removed from uninfected patients, 3 from patients with exit site infections, 4 from patients with peritonitis, and 1 from a patient with both exit site infection and peritonitis. Infecting organisms included 3 of Staphylococcus aureus and one each of Enterobacter sp., Staphylococcus epidermidis, Achromobacter xylosoxidans, Serratia sp., Klebsiella sp., and Candida albicans. Considerable morphological variation in adherence to the peritoneal dialysis apparatus occurred. No inflammatory cells were ever seen in association with infected cuffs, only 2 of the 5 patients with peritonitis had inflammatory cells associated with their catheters. In both instances, these cells tended to occur in clumps and demonstrated no flattening when in contact with the surface. Colonization of the catheter was uneven - bacteria tended to occur in clusters. Extensive matrix formation was evident in several instances, and condensation of this matrix onto the bacteria during the dehydration process rendered clumps of bacterial cells amorphous at times. Bacteria were adherent to the subcutaneous cuff in those patients with exit site infections. Gram-negative bacteria attached to individual dacron fibers of the cuff, often several layers deep. Gram-positive bacteria tended to adhere in clusters.