New fimbrial adhesins of Serratia marcescens isolated from urinary tract infections: description and properties.

Fimbriation, hemagglutination and adherence properties were studied in two strains of S. marcescens (ATCC 43820 and 43821) isolated from the urine of two hospitalized patients in two different hospitals. Studies were performed using electron microscopy (EM), fimbrial purification, recombinant DNA and hemagglutination techniques, hydrophobicity and tests of adherence to uroepithelial cells, catheters and glass. In EM, fimbriae of these two strains showed an inner channel and were 11 nm. thick and 0.76-1.08 microns long. Original strains and the clone GH42-pSF192 (recombinant DNA prepared using E. coli GH42 as recipient and the cosmid SuperCos 1 as a vector) versus negative control (E. coli GH42-SuperCos 1) showed mannose-resistant hemagglutination of tanned erythrocytes and yeast, high hydrophobicity (55.4 and 49.6% at 37C versus 22.8%) and high adherence to borosilicate glass (313,000 and 168,000 CFU/cm.2 versus 17,000 CFU/cm.2), catheters (4.7 x 10(6) and 1.0 x 10(6) CFU/cm.2 versus 3.9 x 10(4) CFU/cm.2) and uroepithelial cells (adherence indexes of 3.82 and 3.29 versus 1.25). The properties of the fimbriae studied were different from those previously described in the genus Serratia, and they were designated as MR/T.