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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...

Over a period of 3 years, Legionella pneumophila serogroup 6 strains were isolated from warm water outlets and dental units in the Dental Faculty and from the Surgery and Internal Medicine Clinics at the University * Corresponding author. serogroup 6 strains isolated during a 3-year surveillance from a water system at the School of Medicine in Dresden, Germany. MATERIALS AND METHODS Water samples. After at least 16 h of stagnation, 0.3to 0.5-liter water samples were collected from dental units and warm water taps in the Faculty of Dentistry, School of Medicine in Dresden over a 3-year period. In the Internal Medicine Clinic, Surgery Clinic, and the bacteriological unit, warm water specimens from taps and faucets were sampled once in the same manner. The four facilities mentioned above are separate buildings, connected with a ring pipe warm water system. This water system is fed by two separate hot water tanks, which were employed one after the other. The temperature in these tanks was adjusted to between 56 and 58°C. During this study, no measures for eliminating legionellae such as superheating to 70°C or chlorination were made. The water temperature in the warm water system ranged from 30 to 50°C at the time of water collection. Legionella strains and culture conditions. Water samples were concentrated by centrifugation at 5,500 x g for 30 min. Legionellae were isolated on ACES [N-(2-acetamido)-2aminoethanesulfonic acid]-buffered charcoal-yeast extract (BCYE) agar medium (4, 8) supplemented with 0.1% ox-ketoglutarate (Sigma Corp.

Ten Legionella pneumophila strains isolated from different sources were analyzed according to their restriction fragment patterns obtained by cleavage of genomic DNA with NotI and Sfi1 and separation by pulsed field electrophoresis. Three L. pneumophila isolates from a nosocomial outbreak in Lubeck (Germany) and three other L. pneumophila strains independently isolated from a water tap located in the care unit where the patients were hospitalized exhibited identical restriction fragment profiles. Therefore, we concluded that these environmental specimens were the source of the Legionnaires disease. Another two isolates from patients and two strains from the environment, all unrelated to the outbreak described, showed different cleavage patterns.

Various Legionella isolates from different sources and origins were analysed by orthogonal field alternation gel electrophoresis of NotI cleaved genomic DNA. The genome of L. pneumophila Philadelphia I, the original isolate of the epidemics in 1976, exhibits only five NotI fragments. Two virulent derivatives, derived from L. pneumophila Philadelphia I, which were obtained by prolonged passage on artificial culture media, did not differ from their isogenic virulent strain according the NotI fragment pattern. By summing the lengths of the NotI fragments, the genome size of L. pneumophila Philadelphia I was calculated as approximately 3.9 Mb. Environmental L. pneumophila strains exhibited different NotI patterns, as did Legionella strains not belonging to the species pneumophila. The usefulness of DNA long range mapping of Legionella ssp. with NotI for epidemiology and evaluation of their evolutionary relationships is discussed.