88
Leavis et al. 2006 ), is maximal among the strains
of Enterococcus faecium isolated in the medical
center effl uents and then decreases along the
continuum. This study shows a preferential
disappearance of epidemiologic strains of E. coli
and Enterococcus faecium in favor of other
subpopulations of these bacterial species less
resistant to antibiotic and probably better adapted
to the aquatic environment (Berthe et al. 2013 ;
Phan and Ferenci 2013 ; Ratajczak et al. 2010 ).
Table 5 Proportion of E. coli isolates (%) resistant to at least one antibiotic in water, along the Seine estuary (January
2006, N = 279; Laroche et al. 2009 )
Stations
Number of strains
of E. coli tested
% of antibiotic-resistant
isolates
a
min-max
Geom.mean
Upstream input
Poses
113
16.0–50.0
30.2
Urban zone
Rouen
77
36.8–39.6
38.2
Le Croisset
104
24.5–94.7
56.6
La Bouille
92
31.0–68.7
49.6
Limit of salinity
Caudebec
94
13.3–58.3
35.7
Mouth of estuary
Tancarville–Honfl eur
174
44.2–60.0
50.1
Table 6 Occurrence of E. coli strains carrying an integron ( intI1, intI2 , or intI3 ) in water sampled along the Seine
estuary (January 2006, N = 279, Laroche et al. 2009 )
Stations
Nb. of E. coli
isolated
% resistant
isolates
a
% of isolates with integron
Total
intI1 intI2 intI1 + intl2
intI3
Upstream input Poses
16
25.0
6.2 0
0
0
6.2
Urban zone
Rouen
58
39.6
8.6 5.2
0
0
13.8
Le Croisset
22
54.5
9.1 4.5
0
0
13.6
La Bouille
35
42.8
2.7 0
0
0
2.7
Limit of salinity Caudebec
53
45.3
3.8 0
0
0
5.7
Mouth of the
estuary
Tancarville–Honfl eur 95
44.2
14.7 0
1.1
0
15.8
a
% of E. coli isolates resistant to one or more antibiotics
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Hospital (N=50)
retirement home
(N=50)
influent WWTP (N=49) treated effluent
WWTP (N=48)
Risle (N=50)
%
E. coli
Fig. 3 Occurrence of multiple-resistant strains of E. coli
along the medical center (hospital and retirement
home)–wastewater treatment plant (WWTP)–river (Risle)
continuum: percentage of isolates of E. coli resistant to at
least three antibiotics , percentage of isolates of E. coli
carrying class 1 integron (Oberlé et al. 2012 )
F. Petit et al.
Leavis et al. 2006 ), is maximal among the strains
of Enterococcus faecium isolated in the medical
center effl uents and then decreases along the
continuum. This study shows a preferential
disappearance of epidemiologic strains of E. coli
and Enterococcus faecium in favor of other
subpopulations of these bacterial species less
resistant to antibiotic and probably better adapted
to the aquatic environment (Berthe et al. 2013 ;
Phan and Ferenci 2013 ; Ratajczak et al. 2010 ).
Table 5 Proportion of E. coli isolates (%) resistant to at least one antibiotic in water, along the Seine estuary (January
2006, N = 279; Laroche et al. 2009 )
Stations
Number of strains
of E. coli tested
% of antibiotic-resistant
isolates
a
min-max
Geom.mean
Upstream input
Poses
113
16.0–50.0
30.2
Urban zone
Rouen
77
36.8–39.6
38.2
Le Croisset
104
24.5–94.7
56.6
La Bouille
92
31.0–68.7
49.6
Limit of salinity
Caudebec
94
13.3–58.3
35.7
Mouth of estuary
Tancarville–Honfl eur
174
44.2–60.0
50.1
Table 6 Occurrence of E. coli strains carrying an integron ( intI1, intI2 , or intI3 ) in water sampled along the Seine
estuary (January 2006, N = 279, Laroche et al. 2009 )
Stations
Nb. of E. coli
isolated
% resistant
isolates
a
% of isolates with integron
Total
intI1 intI2 intI1 + intl2
intI3
Upstream input Poses
16
25.0
6.2 0
0
0
6.2
Urban zone
Rouen
58
39.6
8.6 5.2
0
0
13.8
Le Croisset
22
54.5
9.1 4.5
0
0
13.6
La Bouille
35
42.8
2.7 0
0
0
2.7
Limit of salinity Caudebec
53
45.3
3.8 0
0
0
5.7
Mouth of the
estuary
Tancarville–Honfl eur 95
44.2
14.7 0
1.1
0
15.8
a
% of E. coli isolates resistant to one or more antibiotics
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Hospital (N=50)
retirement home
(N=50)
influent WWTP (N=49) treated effluent
WWTP (N=48)
Risle (N=50)
%
E. coli
Fig. 3 Occurrence of multiple-resistant strains of E. coli
along the medical center (hospital and retirement
home)–wastewater treatment plant (WWTP)–river (Risle)
continuum: percentage of isolates of E. coli resistant to at
least three antibiotics , percentage of isolates of E. coli
carrying class 1 integron (Oberlé et al. 2012 )
F. Petit et al.