Vulnerability and Resilience of Estuaries to Contamination by Antibiotics and Antibiotic-Resistant Bacteria: a Challenge for the Next Decade - Vulnerability of Coastal Ecosystems and Adaptation - page 78

Whatever the antibiotic, the concentrations observed along the
continuum are lowest than the MICs responsible for the selection of
antibiotic-resistant bacteria, which are in the order of 0.032 µg mL -1 to
256 µg mL -1 , and remain inferior to the subinhibiting concentrations
(0.9x CMI to 0.25x CMI), for which a possible effect on bacterial
physiology has been described [DAV 06, GUL 11, KOH 10, ZHA 13].

Antibiotic (g) Hospital Retirement home Commune

- Glycopeptide

- Vancomycin 0 0 n.a

- β-lactams

- Amoxicillin 1,930 544 258,430

- Cloxacillin 0 16 736

- Ampicillin 0 0 0

- Tetracyclines

- Tetracycline 0 0 0

- Doxycycline 1.1 0 1,562

- Fluoroquinolones

- Ciprofloxacin 115 0 980

- Macrolides

- Erythromycin 75 20 n.a

Table 2.3(b). Antibiotic consumption a antibiotic consumption
1month before sampling, b antibiotic consumption 6 months before
sampling based on the sales of antibiotics for all the pharmacies in
the studied zone, NA, not available (from [LEC 13])

2.3.3. Occurence of antibiotic-resistant Escherichia coli and
Enterococcus in the Seine estuary

In parallel with the contamination by antibiotics, a permanent high
level of antibiotic-resistant E. coli has been observed in the Seine
estuary ([LAR 09]; Table 2.4). A high proportion of these strains are
multiresistant to antibiotics (60.5% to 80%), part of which (11.1%)
harbor an integron (Table 2.5). The class 1 integrons are found among
the E. coli strains all along the estuary, whereas only the strains
isolated in the urban zone (Rouen) harbor class 2 integrons. The class