Affiliation:
1. Hospital Universitario Ramón y Cajal, IMSALUD, Madrid, Spain
2. Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
Abstract
ABSTRACT
The contribution of integrons to the dissemination of extended-spectrum β-lactamases (ESBL) was analyzed on all ESBL-producing
Escherichia coli
isolates from 1988 to 2000 at Ramón y Cajal Hospital. We studied 133
E. coli
pulsed-field gel electrophoresis types: (i) 52 ESBL-producing clinical strains (C-ESBL) (16 TEM, 9 SHV, 21 CTX-M-9, 1 CTX-M-14, and 5 CTX-M-10); (ii) 43 non-ESBL blood clinical strains (C-nESBL); and (iii) 38 non-ESBL fecal isolates from healthy volunteers (V-nESBL). Class 1 integrons were more common among C-ESBL (67%) than among C-nESBL (40%) or V-nESBL (26%) (
P
< 0.001) due to the high number of strains with
bla
CTX
-
M
-
9
, which is linked to an In6-like class 1 integron. Without this bias, class 1 integron occurrence would be similar in C-ESBL and C-nESBL groups (47% versus 40%). Occurrence of class 2 integrons was similar among clinical and community isolates (13 to 18%). No isolates contained class 3 integrons. The relatively low rate of class 1 integrons within transferable elements carrying
bla
TEM
(23%) or
bla
SHV
(33%) and the absence of class 2 integrons in all ESBL transconjugants mirror the assembly of translocative pieces containing
bla
TEM
or
bla
SHV
on local available transferable elements lacking integrons. The low diversity of class 1 integrons (seven types recovered in all groups) might indicate a wide dissemination of specific genetic elements in which they are located. In our environment, the spread of genetic elements encoding ESBL has no major impact on the dispersion of integrons, nor do integrons have a major impact on the spread of ESBL, except when
bla
ESBL
genes are within an integron platform such as
bla
CTX
-
M
-
9
.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
161 articles.
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