Previous Article | Next Article ![]()
Journal of Clinical Microbiology, May 2001, p. 1738-1745, Vol. 39, No. 5
Unité de Pathogénie Bactérienne des
Muqueuses1 and Station Centrale de
Microscopie Electronique,2 Institut Pasteur,
75724 Paris Cedex 15, and Unité de Bactériologie,
INSERM EMI 9933, Hôpital Bichat, AP-PH,
Paris,5 France; Department of Microbiology and
Immunology and Department of Obstetrics and Gynecology, The
University of Texas Medical Branch, Galveston, Texas
775553; and Unité des Maladies
Infectieuses Opportunistes, Institut Pasteur de Bangui, BP923
Bangui, Central African Republic4
Received 18 October 2000/Returned for modification 20 December
2000/Accepted 5 February 2001
Operons of the afa family are expressed by pathogenic
Escherichia coli strains associated with intestinal and
extraintestinal infections in humans and animals. The recently
demonstrated heterogeneity of these operons (L. Lalioui, M. Jouve, P. Gounon, and C. Le Bouguénec, Infect. Immun. 67:5048-5059, 1999)
was used to develop a new PCR assay for detecting all the operons of
the afa family with a single genetic tool. This PCR
approach was validated by investigating three collections of human
E. coli isolates originating from the stools of infants
with diarrhea (88 strains), the urine of patients with pyelonephritis
(97 strains), and the blood of cancer patients (115 strains). The
results obtained with this single test and those previously obtained
with several PCR assays were closely correlated. The AfaE adhesins
encoded by the afa operons are variable, particularly with
respect to the primary sequence encoded by the afaE gene.
The receptor binding specificities have not been determined for all of
these adhesins; some recognize the Dr blood group antigen (Afa/Dr+ adhesins) on the human decay-accelerating factor
(DAF) as a receptor, and others (Afa/Dr
0095-1137/01/$04.00+0 DOI: 10.1128/JCM.39.5.1738-1745.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Characterization of AfaE Adhesins Produced by
Extraintestinal and Intestinal Human Escherichia coli
Isolates: PCR Assays for Detection of Afa Adhesins That Do or Do
Not Recognize Dr Blood Group Antigens

adhesins) do not.
Thus, the afa operons detected in this study were
characterized by subtyping the afaE gene using specific
PCRs. In addition, the DAF-binding capacities of as-yet-uncharacterized AfaE adhesins were tested by various cellular approaches. The afaE8 subtype (Afa/Dr
adhesin) was found to
predominate in afa-positive isolates from sepsis patients
(75%); it was frequent in afa-positive pyelonephritis E. coli (55.5%) and absent from diarrhea-associated
strains. In contrast, Afa/Dr+ strains (regardless of the
afaE subtype) were associated with both diarrhea (100%)
and extraintestinal infections (44 and 25% in afa-positive
pyelonephritis and sepsis strains, respectively). These data suggest
that there is an association between the subtype of AfaE adhesin and
the physiological site of the infection caused by
afa-positive strains.
*
Corresponding author. Mailing address: Unité de
Pathogénie Bactérienne des Muqueuses, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris Cedex 15, France. Phone: (1) 40 61 32 80. Fax: (1) 40 61 36 40. E-mail: clb{at}pasteur.fr.
Present address: Molecular Biology Unit, Pasteur Institute of Iran,
Teheran 13164, Iran.
Present address: Università di Roma `La Sapienza,'
Dipartimento di biotecnologie cellulari ed Ematologie, Sezione di
Genetica Molecolare, 1-00161 Rome, Italy.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»