Virulence patterns and long-range genetic mapping of extraintestinal Escherichia coli K1, K5, and K100 isolates: use of pulsed-field gel electrophoresis

Abstract

A total of 127 extraintestinal Escherichia coli strains of the capsule serotypes Kl, K5, and K100 from human and animal sources were analyzed for DNA sequences specific for the genes for various adhesins (P fimbriae [pap] and P-related sequences [prs], S fimbriae [sfa]IFIC fimbriae [foc], and type I fimbriae [fim]), aerobactin (aer), and hemolysin (hly). The expression of corresponding virulence factors was also tested. Twenty-four selected strains were analyzed by long-range DNA mapping to evaluate their genetic relationships. DNA sequences for the adhesins were often found in strains not expressing them, while strains with hemolysin and aerobactin genes usually did express them. Different isolates of the same serotype often expressed different virulence patterns. The use of virulence-associated gene probes for Southern hybridization with genomic DNA fragments separated by pulsed-field gel electrophoresis revealed that a highly heterogeneous restriction fragment length and hybridization pattern existed even within strains of the same serotype. Long-range DNA mapping is therefore useful for the evaluation of genetic relatedness among individual isolates and facilitates the performance of precise molecular epidemiology.Escherichia coli strains of the Ki capsular serotype represent 80% of all E. coli strains isolated from cases of newborn meningitis and sepsis in humans (24,57,63). Moreover, Kl strains and isolates of other serotypes, including 018:K5 and 075:K100, are able to cause urinary tract infection, and Kl E. coli isolates are also often found to be the causative agent of systemic infections in animals (3,48,64,70,71).It has been clear for several years that the capsular antigens, especially Kl and certain types of 0 antigen, are strongly associated with such extraintestinal infections (4, 33, 60, 61, 64), as are specific fimbrial adhesins (18,42,45,46), hemolysin (Hly) (20,22,23), and aerobactin (Aer) (11,28,37). Extraintestinal E. coli isolates may carry different types of fimbrial adhesins which can be distinguished serologically (47) and can show different binding properties. P fimbriae (also termed Pap pili [45]) are associated with pyelonephritis and recognize an Ot-D-galactosyl-(1-4)-p-galactose receptor (29, 66). P-related sequences (Prs) mediate binding to galactosyl-N-acetyl-(ox1-3)-galactosyl-N-acetyl residues (40). The S-fimbrial adhesin (Sfa) interacts with a-sialyl(2-3p)-D-galactose receptor molecules (32,54). Another adhesin, the type I fimbrial adhesin, is produced by pathogenic and nonpathogenic strains and is able to bind to a-D-mannose-containing receptors (47). Fimbriae of serotype FIC are unable to agglutinate erythrocytes but do seem to interact with cells of the human urinary tract (56,68,69).E. coli strains may be subdivided into clones by electrophoretic typing of alloenzymes (4) and by outer membrane protein (OMP) profiles (3). In some cases, the clones have a characteristic serotype based on the 0 lipopolysaccharide and K capsular antigens (4). Attempts have been made to * Corres...

Uropathogenic Escherichia coli

“…All genera within the family Enterobacteriaceae are capable of producing a layer of strain-specific, surface-associated polysaccharides known as capsule (88). Some forms of capsule have been strongly associated with extraintestinal E. coli infections, including urinary tract infection (45,53,72). The kpsMT genes of CFT073 encode the ATP-binding cassette (ABC) transporter components of the group II capsule gene locus (10), have been associated with virulence in UPEC (29), and were present in a single pyelonephritis strain (CFT204) in the CGH analysis.…”

Influence of some bacterial and host factors on colonization and invasiveness of Escherichia coli K1 in neonatal rats

“…Hemagglutination tests and detection of fimbrial adhesins. Hemagglutination in the presence of 1% D-mannose (MRHA) was performed with bacteria grown on CFA agar (12) and with human, bovine, and sheep erythrocytes (12,37). P fimbriae were detected by PF Test (Orion Diagnostika, Espoo, Finland) by agglultnation of a-D-Gal-(1-4)-j3-Galdisaccharide-coated latex particles following the instructions of the supplier.…”

“…Epidemiological studies have shown that only some of the numerous E. coli 0 serogroups are associated with the Kl antigen and that many E. coli Kl strains could be attributed to a small number of clones (2,3). However, E. coli Kl clones were not always uniform in regard to the virulence of strains and geographic differences in clonal predominance and disease were observed (1,3,26,37,51).…”

Virulence determinants of uropathogenic Escherichia coli in fecal strains from intestinal infections and healthy individuals

“…Plasmid DNA was probed for IS1 sequences and the EcoRI restriction and modi¢cation system (EcoRI R-M). For this purpose the following probes were used: for P ¢mbriae the 4-kb HindIII fragment of plasmid pRHU845 [13]; for S ¢mbriae the 1.8-kb EcoRI/ClaI fragment of plasmid pANN801-13 [13]; for colicin V the 0.4-kb HincII/PvuII fragment of plasmid pHK11 [14]; for the aerobactin uptake system the 2.7-kb SalI/BamHI fragment of plasmid pABN5 [15]; for RepFIB the 1.2-kb PstI fragment of plasmid pULB2404 [16]; for IS1 the 0.25-kb PvuII/BstEII fragment of plasmid pTC72#24 (kindly provided by M. Chandler); for the EcoRI restriction and modi¢cation system the 0.4-kb HindIII/PstI fragment of plasmid pJJC1418 [17].…”