Detection of pap, sfa and afa adhesin-encoding operons in uropathogenic Escherichia coli strains: relationship with expression of adhesins and production of toxins.
A total of 243 Escherichia coli strains isolated from patients with urinary tract infections (UTI) were investigated for the presence of pap, sfa and afa adhesin-encoding operons by using the polymerase chain reaction. It was found that 54%, 53% and 2% of the strains exhibited the pap, sfa and afa genotypes, respectively. Pap+ and/or sfa+ strains were more frequent in cases of acute pyelonephritis (94%) than in cases of cystitis (67%) (P < 0.001) and asymptomatic bacteriuria (57%) (P < 0.001). The pap and/or sfa operons were found in 90% of strains expressing mannose-resistant haemagglutination (MRHA) versus 37% of MRHA-negative strains (P < 0.001). The presence of pap and sfa operons was especially significant in strains belonging to MRHA types III (100%) (without P adhesins) and IVa (97%) (expressing the specific Gal-Gal binding typical of P adhesins). Both pap and sfa operons were closely associated with toxigenic E. coli producing alpha-haemolysin (Hly+) and/or the cytotoxic necrotizing factor type 1. There was an apparent correlation between the pap and sfa operons and the O serogroups of the strains. Thus, 93% of strains belonging to O1, O2, O4, O6, O7, O14, O15, O18, O22, O75 and O83 possessed pap and/or sfa operons, versus only 32% of strains belonging to other serogroups (P < 0.001). The results obtained in this study confirm the usefulness of our MRHA typing system for presumptive identification of pathogenic E. coli exhibiting different virulence factors. Thus, 85% of strains that possessed both pap and sfa adhesin-encoding operons showed MRHA types III or IVa previously associated with virulence of E. coli strains that cause UTI and bacteraemia.
Blanco
M
M
Departamento de Microbiología y Parasitología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain.
Blanco
J E
JE
Alonso
M P
MP
Mora
A
A
Balsalobre
C
C
Muñoa
F
F
Juárez
A
A
Blanco
J
J
D018830:Adhesins, Escherichia coli / Q000096:biosynthesis / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001426:Bacterial Proteins / Q000096:biosynthesis*; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics*; D001437:Bacteriuria / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D003556:Cystitis / Q000382:microbiology; D003603:Cytotoxins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins; D005260:Female; D010861:Fimbriae, Bacterial / Q000235:genetics; D005838:Genotype; D006460:Hemolysin Proteins / Q000096:biosynthesis*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009876:Operon; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011704:Pyelonephritis / Q000382:microbiology; D014570:Urologic Diseases / Q000382:microbiology*
D018830:Adhesins, Escherichia coli; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; C060296:cytotoxic necrotizing factor type 1