Comparative genomics of Escherichia coli strains causing urinary tract infections

The virulence determinants of uropathogenic Escherichia coli have been studied extensively over the years, but relatively little is known about what differentiates isolates causing various types of urinary tract infections. In this study, we compared the genomic profiles of 45 strains from a range of different clinical backgrounds, i.e., urosepsis, pyelonephritis, cystitis, and asymptomatic bacteriuria (ABU), using comparative genomic hybridization analysis. A microarray based on 31 complete E. coli sequences was used. It emerged that there is little correlation between the genotypes of the strains and their disease categories but strong correlation between the genotype and the phylogenetic group association. Also, very few genetic differences may exist between isolates causing symptomatic and asymptomatic infections. Only relatively few genes that could potentially differentiate between the individual disease categories were identified. Among these were two genomic islands, namely, pathogenicity island (PAI)-CFT073-serU and PAI-CFT073-pheU, which were significantly more associated with the pyelonephritis and urosepsis isolates than with the ABU and cystitis isolates. These two islands harbor genes encoding virulence factors, such as P fimbriae (pyelonephritis-associated fimbriae) and an important immunomodulatory protein, TcpC. It seems that both urovirulence and growth fitness can be attributed to an assortment of genes rather than to a specific gene set. Taken together, urovirulence and fitness are the results of the interplay of a mixture of factors taken from a rich menu of genes.     

Characteristics ofPseudomonas aeruginosa strains isolated from urinary tract infections

Thirty-three uropathogenic strains ofPseudomonas aeruginosa were investigated for hemolytic activity in both bacterial broth culture filtrates and isolate lyzates, resistance to bactericidal activity of fresh human serum, resistance to six antibiotics and plasmid DNA profile. Twenty-four of the 33 (73%) bacterial filtrates showed lysis of rabbit erythrocytes, as did the three after guinea-pig erythrocyte treatment. Twelve of 33 isolate lysates showed in parallel lysis of both types of erythrocytes used. Serum resistance was found in 17 (52%) isolates, intermediate resistance in 15 (45%) isolates and only one isolate showed serum sensitivity. Resistance to antibiotics was detected as follows (in %): tetracycline 94, kanamycin 79, chloramphenicol 76, septrin 73, ampicillin 64, streptomycin 45, gentamicin 18. None of the isolates investigated showed resistance to colistine. With the exception of one isolate, plasmid DNA was detected in allP. aeruginosa strains.     

Frequent production of toxins by Escherichia coli strains isolated from human urinary tract infections: relation with haemagglutination

Abstract We have investigated the production of heat-labile enterotoxin (LT), Verotoxin (VT), cytotoxic necrotizing factor (CNF), haemolysis (Hly) and lethal activity for mice in 48 Escherichia coli strains isolated from patients with urinary tract infections. Mannose-resistant and mannose-sensitive haemagglutination in these strains were also studied. Among the total strains investigated, 50% were haemolytic, 50% synthesized CNF and 58% were lethal for mice. A total of 33 (69%) strains were toxigenic, showing positive results at least in one of the tests employed for toxin detection. No strain was positive for LT and VT production. We conclude that, in addition to haemolytic and haemagglutinating activities, the production of CNF was closely associated to virulence in E. coli strains isolated from urinary tract infections.     

Serological identification of infection by verocytotoxin-producing Escherichia coli

One hundred sera from patients with haemolytic ureamic syndrome were screened for antibodies to the lipopolysaccharide (LPS) of Escherichia coli serogroup 05, 026, 0115, 0128, 0145 and 0153, and Shigella dysenteriae 1. Three sera contained antibodies to the LPS of E. coli belonging to serogroup 05.     

Pathogenic characteristics of Escherichia coli strains in cases of asymptomatic bacteriuria and symptomatic urinary tract infections

The aim of this study was to examine if E. coli isolated from asymptomatic bacteriuria differed in pathogenic features from strains isolated from symptomatic infections of urinary tract. In this study 130 strains of E. coli isolated from women having asymptomatic bacteriuria and 112 strains isolated from patients with symptoms of urinary tract infection were examined. It was shown that E. coli isolated from patients with symptomatic urinary tract infection showed the more frequently ability to cause mannose-resistant haemagglutination of human erythrocytes, resistance to bactericidal activity of serum and haemolytic properties than those isolated from asymptomatic bacteriuria. These strains showed also the higher ability to adhere to Vero cells in tissue culture. Among E. coli strains isolated from persons with asymptomatic bacteriuria the pathogenic features were most frequently found in strains from healthy women and the most rarely in isolated from diabetic women.     

Molecular identification of Candida species from urinary infections in Honduras

Background

Candiduria is a common infection among hospitalised patients. Although the clinical relevance of yeasts in urine is not clearly defined, fungal urinary tract infections have increased significantly in the last decades, becoming a growing public health problem. Candida albicans is the most commonly reported species in urinary infections, although other species of the genus are becoming particularly important, because some of them are linked with resistance to antifungal drugs.

The prevalence of plasmid-mediated quinolone resistance genes among Escherichia coli strains isolated from urinary tract infections in southwest Iran

Molecular Biology Reports - The extensive and inappropriate use of quinolones, which are frequently used as an effective treatment for urinary tract infection (UTI) patients, has led to resistance...     

Serological analysis and identification of feline calicivirus strains isolated in Sicily

The isolation and characterization of calicivirus strains from symptomatic cats are reported. The correlations between the feline calicivirus strains isolated and the vaccinal strain FCV F9 were investigated by a virus-neutralization test, suggesting a strong antigenic variability.     

Aerobactin production and dulcitol fermentation in clonal groups of Escherichia coli O1: K1 strains from urinary tract infections

Abstract 70 urinary Escherichia coli O1:K1 strains were characterized for O1 antigen factors, mannose-resistant hemagglutination of human erythrocytes, flagellar and fimbrial antigens, dulcitol fermentation and aerobactin production. On the basis of their O1 and H antigens the strains could be assigned to 6 distinct groups. The most prevalent groups were: O1abcd: H⁻ :F9 (33 strains; pattern II), O1abc: H⁻ :F11 (9 strains; pattern IV), and O1abc: H7: F11 (19 strains; pattern V). Strains with patterns IV and V, both expressing fimbrial antigen F11, fermented dulcitol and produced aerobactin, whereas strains with pattern II were negative for both characteristics.     

Comparison of genomic profiles of Escherichia coli isolates from urinary tract infections

Formally included in the larger category of extraintestinal pathogenic Escherichia coli (ExPEC), the uropathogenic E. coli remains the most frequent cause of urinary tract infection (UTI), an important endemic health problem. The genomic DNA of E. coli urinary isolates from adults diagnosed with urinary tract infections and of E. coli fecal isolates from healthy subjects was analysed by PCR for the presence of virulence factor encoding genes pap, sfa/foc, afa, hly and cnf and by field inversion gel electrophoresis (FIGE) fingerprinting of XbaI DNA macrorestriction fragments. The aim was to obtain more detailed microbiological data regarding the community circulating strains in respect of their virulence potential and genetic relatedness. Almost 70% of the urinary strains carried at least one of the target virulence genes, and only 35.5% of the fecal E. coli strains were positive in the PCR screening. Taking into account the virulence genotypes exhibited, a part of the strains isolated from the urinary tract could be defined as belonging to the ExPEC pathotype. A unique FIGE profile was obtained for each of the selected isolates and the dendrogram generated by Taxotron software package analysis suggested a polyclonal population of potential uropathogenic strains clustered into 14 groups of only 60% similarity. For better understanding the epidemiology of UTIs, diseases commonly caused by such a heterogeneous species like E. coli, molecular analysis methods could be essential due to their increased power of identification and fingerprinting.     

Virulence characteristics of Escherichia coli isolates from children with urinary tract infections

The urinary tract is among the most common sites of bacterial infection and E. coli is by far the most common infecting agent in children and adults of both sexes. In an attempt to evaluate the intrinsic virulence of E. coli uroisolates from children, 54 strains were assessed by using PCR for the presence of five representative genetic determinants coding for adherence systems (pap, sfa/foc, afa), and toxins (hly and cnf). The prevalence of pap, sfa/foc and afa genes was 55%, 54%, and 44%, respectively. Hemolysin-encoding gene hly was detected in 55% strains, while cnf was exhibited by 35% of the screened E. coli isolates. Among the 39 PCR positive strains isolated from children's urine cultures the co-occurrence of the various targeted virulence genes was detected in 30 strains, the virulence profiles identified suggesting the presence of their localization on chromosomal regions known as pathogencity-associated islands. The rapid and reliable detection of the intrinsic virulence potential by this molecular approach could be very useful when evaluating the importance of microorganism pathogenicity versus host's susceptibility for developing an overt symptomatology of infection.     

儿童泌尿系感染大肠埃希菌的耐药性分析

目的 了解大肠埃希菌在儿童中的感染情况及其耐药性.方法 对中段尿标本进行分离培养及鉴定,药敏试验用K-B法,检测ESBLs用表型确证试验,药敏结果分析用WHONET 5.5软件,统计分析采用x2检验.结果 2009年1月至2011年12月从儿科门诊和病房送检的1755份中段尿标本中共检出85株大肠埃希菌,检出率为4.8％,男女比为6:11; ＜3岁的婴幼儿组57例,占67.1％;3～6岁育龄前儿童17例,占20.0％;＞6岁儿童11例,占12.9％;产ESBLs的大肠埃希菌占60.0％;85株大肠埃希菌对亚胺培南和美罗培南全部敏感,对头孢哌酮/舒巴坦、哌拉西林/他唑巴坦和阿米卡星的敏感率均为90％以上,产ESBLs的大肠埃希菌对氨苄西林、头孢唑啉、头孢他啶、头孢曲松、头孢吡肟、头孢西丁、头孢呋新酯、左旋氧氟沙星和罗红霉素的耐药率较非产ESBLs菌株的耐药率高,P值均＜0.05,差异有统计学意义.结论 儿童泌尿系感染大肠埃希菌,可以选用的抗菌素已极为有限,临床要谨慎用药,并及时根据药敏结果修正药物种类.     

Serological identification of enterotoxigenic staphylococci from cheese

Single and double gel-diffusion techniques were employed to examine serologically coagulase-positive staphylococci from cheese for enterotoxigenicity. Supernatant fluid from sac cultures was examined for enterotoxins A and B. The results indicated that 9 of 155 cultures from market cheese and 7 of 77 cultures from food-poisoning cheese produced enterotoxin A, and that none of the cultures produced detectable levels of enterotoxin B. Results of serological tests were confirmed by intravenous injection of cats.     

Frequency of Escherichia coli serotypes in urinary infections]

Among the large O-groups of E.coli isolated from urinary-tract infections, a few groups appear more frequent. The AA report about this frequency in the district of L'Aquilla. Of 147 stocks of E.coli, the most frequent O-groups are the O6 (28,5%), the O75 (20,4%), the O2 (10,2%), the O18 (6,1%), the O5 (4,1%), the O39 (2%).     

Comparison of some adhesive properties of Pseudomonas aeruginosa strains isolated from respiratory and urinary tract infections

The aim of the paper was the comparison of adhesive properties concerning pathogenic potential of P. aeruginosa strains isolated from the patients with respiratory tract infections and from the patients with urinary tract infections. It was stated that P. aeruginosa strains had no haemagglutinating properties when cultured on a solid medium. Bacteria cultured in a liquid medium showed an increase of these properties in 48 h cultures as compared with 24 h cultures. They were not sensitive to heating. The haemagglutinating properties of the most strains were inhibited by D-mannose. These results seem to suggest that in P. aeruginosa strains fimbriae play an important role in adhesion. On the other hand, the mechanism of adhesion is not uniform as shows mannose-sensitivity of some strains and its lack in the other haemagglutinating strains. The most effective agglutination of human erythrocytes seems to be caused by the species specificity of the individual strains isolated from humans. The higher attachment of P. aeruginosa strains isolated from the urinary tract infections than those from respiratory tract infections to "Vero" cells suggests that these two strains populations may differ in their pathogenic potential to various tissues.     

Frequency of Escherichia coli strains producing the cytotoxic necrotizing factor (CNF1) in nosocomial urinary tract infections

The presence of cytotoxic necrotizing factor 1 (CNF1), together with various associated virulence factors (alpha-haemolysin, P-, S- and A-fimbriae), was screened in 175 uropathogenic Escherichia coli strains isolated from hospitalized adult patients. The cnf1 gene was detected in 30% of the selected strains independently of the severity of the clinical urinary infection. A significant association between CNF1, haemolytic activity and the products of the pap/sfa genes was found. However, CNF1 appeared not to play a major role in nosocomial E. coli urinary tract infections.