S-Fimbria-Encoding Determinant sfa _I Is Located on Pathogenicity Island III ₅₃₆ of Uropathogenic Escherichia coli Strain 536

Abstract

The sfa I determinant encoding the S-fimbrial adhesin of uropathogenic Escherichia coli strains was found to be located on a pathogenicity island of uropathogenic E. coli strain 536. This pathogenicity island, designated PAI III 536 , is located at 5.6 min of the E. coli chromosome and covers a region of at least 37 kb between the tRNA locus thrW and yagU. As far as it has been determined, PAI III 536 also contains genes which code for components of a putative enterochelin siderophore system of E. coli and Salmonella spp. as well as for colicin V immunity. Several intact or nonfunctional mobility genes of bacteriophages and insertion sequence elements such as transposases and integrases are present on PAI III 536 . The presence of known PAI III 536 sequences has been investigated in several wild-type E. coli isolates. The results demonstrate that the determinants of the members of the S-family of fimbrial adhesins may be located on a common pathogenicity island which, in E. coli strain 536, replaces a 40-kb DNA region which represents an E. coli K-12-specific genomic island.Extraintestinal Escherichia coli strains can be grouped into three different pathotypes: meningitis E. coli (MENEC) strains, which cause newborn meningitis; septicemia E. coli (SEPEC) strains, which cause septicemia infections; and uropathogenic E. coli (UPEC) strains, which are the most frequently isolated causative agents of infections of the bladder and the kidney in humans (45, 57). They are characterized by the expression of certain virulence factors, including adhesins, which contribute to the establishment of the infection and distinguish them from nonpathogenic E. coli strains (39). Members of the S-fimbrial family of adhesins are frequently expressed in extraintestinal E. coli strains isolated from men. This adhesion family consists of S-fimbriae (Sfa), with its subtypes SfaI and SfaII; F1C-fimbriae (Foc); and S/F1C-related fimbriae (Sfr) (25,46). The AC/I-fimbriae (Fac) which are expressed by avian-pathogenic E. coli strains also belong to the S-family of adhesins (5, 6). All members are highly similar in the organization of their determinants and the sequence identities of the encoded proteins (45-47, 54). However, they differ in their receptor and therefore in their tissue specificity. Sfimbrial adhesins recognize ␣-sialyl-2-3-␤-lactose-containing receptors and are predominantly expressed by strains which cause sepsis and meningitis but also by urinary tract infection (UTI) isolates (32, 33), whereas F1C-fimbrial adhesins bind to ␤-GalNac-1,4-␤-Gal-containing structures (30) and are preferentially expressed by UTI isolates.The uropathogenic E. coli strain 536 (O6:K15:H31) has previously been shown to produce various types of fimbrial adhesins, including type 1, P-related, and S-fimbriae (26). The presence of four pathogenicity islands (PAIs I 536 to IV 536 ) has been described for E. coli strain 536 so far. All four PAIs have common characteristics which are typical of pathogenicity islands, i.e., association with a tRNA gene and ...

Evaluation of pathogenicity islands in uropathogenic Escherichia coli isolated from patients with urinary catheters

“…In contrast to the present study, PAI IIJ96 and PAI I536 were detected at a relatively high frequency, and PAI III536 showed the lowest frequency in UPEC strains and was not detected in commensal isolates [14]. Dobrindt et al reported that PAI III536 was more common than PAI II536 or PAI I536 in UPEC strains, including isolates from women with chronic UTIs, in contrast with our UPEC isolates from patients without catheters [11]. In other reports [20], PAI III536 and PAI II536 were reported as unstable PAIs, which could be the reason for the difference between our results and Sabate et al's findings.…”

“…In a study by Sabate et al, PAI IV536 was found most frequently in both commensal and UPEC isolates from patients with pyelonephritis and urinary sepsis [14]. In most studies worldwide, the presence of PAI IV536 in the Enterobacteriace family is documented, and this marker is known as broad-hostrange PAI or high-pathogenicity island (HPI) [11,18,19]. Our results also showed that one UPEC isolate from patients with an implanted catheter and four UPEC isolates from patients without urinary catheters suffering from sepsis carried only PAI IV536 as a single PAI marker.…”

“…Multiplex PCR no. 2 was performed to identify PAI IIJ96, PAI I536, PAI II536, PAI ICFT073, and PAI IJ96, obtaining 2,300, 1,800, 1,000, 930, and 400 bp PCR products, respectively [11,14,15]. The amplifications were carried out using an Eppendorf master cycler (Eppendorf Mastercycler Gradient, Foster City, USA) in a total volume of 50 µL including 1U Taq DNA polymerase (Fermentase, Burlington, Canada), 5 μL of 10 × reaction buffer, 1.5 mM MgCl2, 1 μL of 0.2 mM of dNTP (Fermentase, Burlington, Canada), 5 μL template DNA, 1 μL (10 pmol) forward and reverse primers, and nuclease-free water.…”

“…PAIs were reported in UPEC strain 536 for the first time [9]. There are three major strains of UPEC, including CFT073, 536 and J96, and different types of PAIs have been documented for each one [11,12]. PAIs are mobile genetic elements that provide a strong route for horizontal transfer of virulence genes, which is why these DNA regions are involved in bacterial evolution, especially among pathogenic bacteria [9].…”

Characterizing the APEC pathotype

“…For example, several of these pTJ100-related genes are known to occur in PAI of human ExPEC strains. The salmochelin operon, containing iroN, has been found in PAI III 536 along with several other genes that might be linked to avian E. coli virulence, including tsh and certain components of the ColV operon [9,10]. Therefore, future researchers will need to be aware that although these pTJ100-associated genes are widespread among APEC that they may not be plasmid-located in all APEC.…”