RIBOTYPING AS AN EPIDEMIOLOGIC TOOL FOR ESCHERICHIA-COLI

Restriction fragment length polymorphism of ribosomal RNA genes was an alysed among 133 Escherichia coli strains predominantly from blood and urine, including 21 isolates from faeces of healthy persons. The stra ins had also been characterized for their O:K:H serotypes, for the pre sence of P, S and type 1C fimbriae, non-P, non-S mannose-resistant hae magglutinins and haemolysin production. HindIII-digested genomic DNA w as subjected to Southern blot analysis with either plasmid pKK3535 con taining E. coli rRNA operon or purified rRNA as a probe. Among the 133 strains 20 ribotypes were obtained. The distribution of strains into different ribotypes generally correlated with their O:K:H serotype. Ri botype variation within serotypes was mainly seen among strains with t he K5 capsule. The origin of the strains or the presence of virulence- associated factors did not correlate with the ribotype. In conclusion, ribotyping appears to be a valuable method in epidemiologic studies e specially when the serotyping methods are not available.