Urinary Tract Infection Strains Research Articles

Cloning and characterization of the S fimbrial adhesin II complex of an Escherichia coli O18:K1 meningitis isolate

S fimbrial adhesins (Sfa), which are able to recognize sialic acid-containing receptors on eukaryotic cells, are produced by Escherichia coli strains causing urinary tract infections or newborn meningitis. We recently described the cloning and molecular characterization of a determinant, termed sfaI, from the chromosome of an E. coli urinary tract infection strain. Here we present data concerning a S fimbria-specific gene cluster, designated sfaII, of an E. coli newborn meningitis strain. Like the SfaI complex, SfaII consists of the major subunit protein SfaA (16 kDa) and the minor subunit proteins SfaG (17 kDa), SfaS (15 kDa), and SfaH (29 kDa). The genes encoding the subunit proteins of SfaII were identified and sequenced. Their protein sequences were calculated from the DNA sequences and compared with those of the SfaI complex subunits. Although the sequences of the two major SfaA subunits differed markedly, the sequences of the minor subunits showed only a few amino acid exchanges (SfaG, SfaH) or were completely identical (SfaS). The introduction of a site-specific mutation into the gene sfaSII and subsequent analysis of an SfaS-negative clone indicated that sfaSII codes for the sialic acid-specific adhesin of the meninigitis isolate. These data were confirmed by the isolation and characterization of the SfaSII protein and the determination of its N-terminal amino acid sequence. The identity between the sialic acid-specific adhesins of SfaI and SfaII revealed that differences between the two Sfa complexes with respect to their capacities to agglutinate erythrocytes must result from sequence alterations of subunit proteins other than SfaS.

Serum dependent expression of Enterococcus faecalis adhesins involved in the colonization of heart cells

Our previous studies have shown that the adhesive ability of Enterococcus faecalis is dependent on the strain and is further modified by growth in serum. The data reported here demonstrate that E. faecalis adherence is mediated by carbohydrate residues present on the bacterial cell surface. Some of these ( d-mannose and d-glucose) are expressed by strains isolated from both urinary tract infections (UTI) and endocarditis (EN) when the cells are grown in brain-heart infusion broth (BHIB), and mediate adherence to either urinary tract epithelial cells or the Girardi Heart (GH) cell line. Other residues are present only on EN strains ( d-galactose and l-fucose) and mainly mediate adherence to GH cells. These ligands can also be expressed by UTI isolates after growth in serum. d-galactose-bearing adhesins also seem to be involved in internalization of serum grown UTI strains and BHIB or serum grown EN isolates into GH cells.

Enterococcus faecalis: specific and non-specific interactions with human polymorphonuclear leukocytes

In previous studies we have demonstrated that the ability of Enterococcus faecalis to adhere to and to be internalized in human urinary tract epithelial cells, Girardi Heart cells and human polymorphonuclear leukocytes (PMNs), was dependent on whether the strain had been isolated from urinary tract infections (UTI) or endocarditis (EN) respectively. These properties were further modified by growth of the organism in human serum. In the present report, using competition assays we show that adhesins containing a D-glucose moiety play a role in mediating the interactions between human PMNs and E. faecalis strains isolated from UTI and grown in brain-heart infusion broth (BHIB). On the other hand, adhesins containing both D-glucose and D-galactose moieties were involved in the interactions between PMNs and serum grown UTI isolates or EN isolates grown in either BHIB or human serum. Moreover, the impairment in the association between both UTI and EN strains after growth in serum appears to be at least partially related to a decrease in enterococcal surface hydrophobicity.

Enterococcus faecalis: specific and non-specific interactions with human polymorphonuclear leukocytes

In previous studies we have demonstrated that the ability of Enterococcus faecalis to adhere to and to be internalized in human urinary tract epithelial cells, Girardi Heart cells and human polymorphonuclear leukocytes (PMNs), was dependent on whether the strain had been isolated from urinary tract infections (UTI) or endocarditis (EN) respectively. These properties were further modified by growth of the organism in human serum. In the present report, using competition assays we show that adhesins containing a D-glucose moiety play a role in mediating the interactions between human PMNs and E. faecalis strains isolated from UTI and grown in brain-heart infusion broth (BHIB). On the other hand, adhesins containing both D-glucose and D-galactose moieties were involved in the interactions between PMNs and serum grown UTI isolates or EN isolates grown in either BHIB or human serum. Moreover, the impairment in the association between both UTI and EN strains after growth in serum appears to be at least partially related to a decrease in enterococcal surface hydrophobicity.

Deletions of chromosomal regions coding for fimbriae and hemolysins occur in vitro and in vivo in various extra intestinal Escherichia coli isolates

Fimbrial adhesins and hemolysins contribute to pathogenicity of extraintestinal Escherichia coli isolates causing urinary tract infections (UTI), sepsis and new born meningitis (NBM). Using gene cloning techniques and pulse field electrophoresis in combination with Southern hybridizations it was demonstrated that the genetic determinants coding for P and ‘P-related’ fimbrial adhesins and hemolysins are closely linked on the chromosomes of different pathogenic E. coli wild-type isolates. For two UTI strains, 536 (06:K15) and J96 (04:K6), a co-deletion of the linked gene clusters coding for hemolysin and fimbriae was observed. The deleted DNA regions which also comprise flanking DNA sequences were termed ‘pathogenicity DNA islands’. Such ‘pathogenicity DNA islands’ were also detected in the genome of 018:K1 isolates of OMP type 6 but were absent on the chromosomes of O18: K1 strains of OMP type 9. A mutant strain, 536-22 was selected from rat kidneys after intraurethral infection of animals with the wild-type parental strain 536. This particular isolate also shows deletions of ‘pathogenicity islands’ leading to a non-pathogenic phenotype. It is therefore concluded that excisions of ‘pathogenicity islands’ from chromosomes of pathogenic E. coli strains are not restricted to the laboratory but also occur in vivo. The generation of deletions may represent a general mechanism of bacterial virulence modulation.

Resistance to Quinolones in Gram-Negative Microorganisms: Mechanisms and Prevention

Bacterial resistance to quinolones is essentially the result of mutations on several genes involved in the synthesis of DNA-gyrase or in proteins of the cellular envelope. A single mutational event may lead to complete resistance to older quinolones, but clinical resistance to newer quinolones such as norfloxacin requires two or more mutations. Prevention of resistance to norfloxacin requires prevention of the strains carrying 'first mutations' (by a controlled use of older quinolones) and the early detection of such strains. If microbiologic and pharmacologic data are taken into account at the same time, the incidence of norfloxacin-resistant strains in urinary tract infections will remain insignificant.

Beta-lactamase types and beta-lactam resistance ofEscherichia coli strains with chromosomally mediated ampicillin resistance

On the basis of isoelectric focusing six beta-lactamase types could be distinguished in ampicillin-resistant and ampicillin-sensitive strains of Escherichia coli. More than 90% of the ampicillin-resistant strains produced the same beta-lactamase type. The serotypes found in a group of ampicillin-resistant urinary tract infection strains did not represent the distribution usually found in urinary tract isolates. Chromosomal ampicillin resistance was always associated with high cephalothin MIC values and increased resistance to other beta-lactam antibiotics of the cephalosporin group.

Adhesiveness and invasiveness of staphylococcal species in a cell culture model.

A model was established for the study of adhesiveness and invasiveness of staphylococcal species. Five collection strains from each of the species Staphylococcus aureus, S. epidermidis, and S. saprophyticus and 26 fresh isolates from patients with urinary tract infections were tested for adhesiveness and invasiveness in HEp-2 cell cultures. All the strains of S. saprophyticus were able to invade the cells and localize intracellularly in the cultures, whereas the invasive potential among the strains of S. aureus and S. epidermidis was lower. The number of adhesive bacteria was also highest among the S. saprophyticus strains, whereas S. epidermidis was the least adhesive. The model may be suitable for further study of urinary tract infection strains.

Role of adherence in pathogenesis of Enterococcus faecalis urinary tract infection and endocarditis

Enterococcus faecalis strains isolated from urinary tract infections (UTIs) and endocarditis were analyzed for their ability to adhere to urinary tract epithelial cells (ECs) and Girardi heart (GH) and human embryonic kidney (HEK) cell cultures. UTI isolates adhered to urinary tract ECs more efficiently than to the cultured cells, at the same time showing the least affinity for GH cells. In contrast, endocarditis isolates adhered to GH cell cultures more readily than to urinary tract ECs. Moreover, although strains isolated from endocarditis adhered to GH cells more efficiently than those derived from UTI, the latter strains adhered to urinary tract cells better than the former. Studies of the ability of GH and HEK cells to internalize E. faecalis showed that for UTI isolates, 9 to 74% of adhered bacteria were internalized, while for endocarditis isolates, the percentage varied from 76 to 82%. All strains were able to associate with human neutrophils; endocarditis strains, however, associated less efficiently than UTI isolates. Growth in serum raised the adherence of all tested strains by at least 1.5- to 3-fold, with the greatest increase being observed in UTI strain adherence to GH cells (8-fold). In contrast, the association of serum-grown cells with polymorphonuclear leukocytes was reduced by two- to fivefold. In both cases, the observed serum-dependent alterations were cancelled by a few subcultures in brain heart infusion broth. These results indicate that adhesive properties are important virulence factors in the pathogenesis of UTI and endocarditis and also suggest that UTI strains showing the highest invasion and adhesive potential invade the kidneys, cause bacteremia, and, after having expressed the serum-dependent surface modification, colonize the heart.

Characterization of escherichia coli wild-type strains by means of agglutination with antisera raised against cloned P-, S-, and MS-fimbriae antigens, hemagglutination, serotyping and hemolysin production

E. coli strains isolated from patients with urinary tract infections (UTI) very often possess mannose-sensitive (MS) and mannose-resistant (MR) adherence factors (fimbriae). According to their receptor specificity the mannose-resistant adhesins can be divided into several types, P, S, M and X. We have cloned the determinants of three groups of UTI E. coli adhesins, MS, P and S, and prepared specific antisera against the fimbriae antigens. 189 hemagglutination (HA+)-positive strains, 96 fecal isolates and 93 strains isolated from UTI have been tested with these specific antisera and further characterized by receptor specific HA, HA patterns and further of the "common O serogroups" 01, 02, 04, 06, 07, 08, 018, 025, 075, most prevalent in UTI, and hemolysin production. 68 (73%) of the UTI strains and 50 (52%) of the fecal isolates showed P-receptor specificity; 16 (17%) of the uropathogenic bacteria and 33 (34%) of the fecal strains exhibited S, M or X-fimbriae antigens. 24% of the P-hemagglutinating (P+) strains reacted with P (F8)-specific antiserum. In contrast, more than three quarter of the S+-strains were agglutinated by S-specific antiserum. HA-pattern VI and 018 antigen were found to be associated with P-fimbriae strains, whereas HA-pattern V and VII and the O antigens 02 (M-type), 06 and 018 (S-type) occurred most frequently in P--strains. A high percentage of P-fimbriated strains showed mannose-sensitive hemagglutination and hemolysin production.

Cloned hemolysin genes from Escherichia coli that cause urinary tract infection determine different levels of toxicity in mice.

After intraperitoneal injection of mice with Escherichia coli strains isolated from patients with urinary tract infections, the mortality due to hemolytic (Hly+) and nonhemolytic (Hly-) isolates was 77 and 40%, respectively. Deletion of the chromosomal hemolysin (hly) determinant in an E. coli O6:K15:H31 urinary tract infection strain led to a significant reduction in toxicity for mice, and its reintroduction on a recombinant plasmid partially restored the original toxicity. Although introduction of the cloned plasmid pHly152-encoded hly determinant into the Hly- E. coli O6 mutant strain increased toxicity by only a marginal degree, transformation with the cloned chromosomal hly determinants from two E. coli strains of serotypes O18ac:K5:H- and O75:K95:H? resulted in markedly greater toxicity, even exceeding that of the original Hly+ E. coli O6 wild-type strain.

Typisierung von E. coli-rauhstämmen mit Phagen

Abstract Two phage-sets were used for the typing of 408 E. coli rough strains isolated from patients with urinary tract infections. Using the 13 phages A to M (11), we were able to type 225 (55.1 per cent) strains. 143 (35 per cent) of these strains were found to have K antigen. 84 different phage patterns could be recognized. Phage patterns GHK, M, F, and AM were the most common ones found. The application of the typical rough phages BrlO, C21, 6SR, FP1, T4, and the Felix O (FO) phage led to the successful typing of 143 (35 per cent) strains, 80 of which (19.6 per cent) had a K antigen. About 70 per cent of the strains typable were found to belong to phage patterns which were represented by single phages. 24 different R phage patterns were observed. Considering both phage-sets the total typability amounted to 67 per cent. It is concluded that phage typing may be useful for the typing of E. coli rough strains in urinary tract infections in order to distinguish between relapse and reinfection.