80
In the same samples, occurrence of antibiotic- resistant E. coli and those
harboring a class 1 integrons was signifi cantly ( p -value < 0.001) decreased
along the continuum. Among Enterococcus populations, E. faecium was
mainly isolated (from 89 to 98 %). All E. faecium isolates from medical
center effl uents were multiple antibiotic resistant, containing erm (B) and
mef (A) genes, and belonged to the hospital-adapted clonal complex 17
(CC17). The relative proportion of CC17 decreased in favor of other
subpopulations, less resistant to antibiotics. In water, only persistent
compounds were found (quinolones, macrolides, sulfonamides), but they
did not correspond to the major resistances in E. coli and Enterococcus
(penicillins, tetracyclines).
1
Introduction
1.1
Why Does the Ecosystem
Matter for Human Health
in the Emergence of Antibiotic
Resistance?
One of the major challenges of the next decades
will be the assessment of how ecosystem changes
could affect human health. Thus, the assessment
of the microbiological vulnerability and the resilience of the aquatic environment to contamination by fecal germs, which in industrialized
countries, is accompanied by pharmaceutical
contamination, will be a major health concern
(Millennium Ecosystem Assessment, http://
milleniumassessment.org ).
Among pharmaceuticals, antibiotics have a
unique character: with emerging contaminants of
aquatic environments, their intensive use in
human and animal medicine is also responsible
for the increase of resistance to antibiotics in
bacteria (Aarestrup 2005 ; Seveno et al. 2002 ).
To date, the concentrations of antibiotics in water
reported in the bibliography are dependent on the
analytical methods and methods of sampling.
However, the maximal values (in the order of a
hundred µg L
−1 ) are observed in effl uent from
hospitals or from pharmaceutical factories. In
surface water, lower concentrations (in the order of
ten µg L
−1 ) are detected immediately downstream
from the discharge of wastewater treatment
plants (WWTPs), mainly due to the dilution in
the receiving environment and the degradation of
the antibiotic compounds ( Kummerer 2009 ;
Tamtam et al. 2008 ).
The emergence of bacterial resistance has
been recognized as a major problem in public
health by the World Health Organization (WHO
2001 ). Since the 1950s and the beginning of
the large-scale use of antibiotics, pathogenic
bacteria, initially sensitive to antibiotics, have
very rapidly acquired resistance mechanisms,
some of which were acquired from environmental bacteria. As an example, the pandemic of
the extended- spectrum beta-lactamases (ESBLs),
whose therapeutic consequences are dramatic, is
consecutive to a genetic transfer from environmental bacteria (e.g., CTX-M from Kluyvera spp.,
Poirel et al. 2002 ).
1.2
Bacterial Antibiotic
Resistance: A Global
Ecological Process
Bacterial resistance to antibiotics is a complex
ecological phenomenon which should be understood, by considering the circulation of microorganisms and the corresponding resistance genes
within the four major ecosystems: humans,
animals, soil, and water (Martinez 2008 , 2009 ;
Nwosu 2001 ; Wellington et al. 2013 ; Fig. 1 ).
F. Petit et al.
In the same samples, occurrence of antibiotic- resistant E. coli and those
harboring a class 1 integrons was signifi cantly ( p -value < 0.001) decreased
along the continuum. Among Enterococcus populations, E. faecium was
mainly isolated (from 89 to 98 %). All E. faecium isolates from medical
center effl uents were multiple antibiotic resistant, containing erm (B) and
mef (A) genes, and belonged to the hospital-adapted clonal complex 17
(CC17). The relative proportion of CC17 decreased in favor of other
subpopulations, less resistant to antibiotics. In water, only persistent
compounds were found (quinolones, macrolides, sulfonamides), but they
did not correspond to the major resistances in E. coli and Enterococcus
(penicillins, tetracyclines).
1
Introduction
1.1
Why Does the Ecosystem
Matter for Human Health
in the Emergence of Antibiotic
Resistance?
One of the major challenges of the next decades
will be the assessment of how ecosystem changes
could affect human health. Thus, the assessment
of the microbiological vulnerability and the resilience of the aquatic environment to contamination by fecal germs, which in industrialized
countries, is accompanied by pharmaceutical
contamination, will be a major health concern
(Millennium Ecosystem Assessment, http://
milleniumassessment.org ).
Among pharmaceuticals, antibiotics have a
unique character: with emerging contaminants of
aquatic environments, their intensive use in
human and animal medicine is also responsible
for the increase of resistance to antibiotics in
bacteria (Aarestrup 2005 ; Seveno et al. 2002 ).
To date, the concentrations of antibiotics in water
reported in the bibliography are dependent on the
analytical methods and methods of sampling.
However, the maximal values (in the order of a
hundred µg L
−1 ) are observed in effl uent from
hospitals or from pharmaceutical factories. In
surface water, lower concentrations (in the order of
ten µg L
−1 ) are detected immediately downstream
from the discharge of wastewater treatment
plants (WWTPs), mainly due to the dilution in
the receiving environment and the degradation of
the antibiotic compounds ( Kummerer 2009 ;
Tamtam et al. 2008 ).
The emergence of bacterial resistance has
been recognized as a major problem in public
health by the World Health Organization (WHO
2001 ). Since the 1950s and the beginning of
the large-scale use of antibiotics, pathogenic
bacteria, initially sensitive to antibiotics, have
very rapidly acquired resistance mechanisms,
some of which were acquired from environmental bacteria. As an example, the pandemic of
the extended- spectrum beta-lactamases (ESBLs),
whose therapeutic consequences are dramatic, is
consecutive to a genetic transfer from environmental bacteria (e.g., CTX-M from Kluyvera spp.,
Poirel et al. 2002 ).
1.2
Bacterial Antibiotic
Resistance: A Global
Ecological Process
Bacterial resistance to antibiotics is a complex
ecological phenomenon which should be understood, by considering the circulation of microorganisms and the corresponding resistance genes
within the four major ecosystems: humans,
animals, soil, and water (Martinez 2008 , 2009 ;
Nwosu 2001 ; Wellington et al. 2013 ; Fig. 1 ).
F. Petit et al.