Table 1

Antibiotic resistance genes detected in cultured bacteria and class 1 integron gene cassettes recovered from suspended floc across four variably impacted freshwater systems

ResistanceGene(s)Detectiona
HamiltonTorontoGuelphColdspringTotal
CICICICICI
Aminoglycoside transferaseaac(3)Ia+++310
aac(3)IVa+
aac(6′)Ib+
aadA1 like++
aadA2 like+
aadA4 like++
ant(2″)Ia+
strB++
Beta-lactamase (class A)bblaCTX-M-1++35
blaCTX-M-9+
blaLEN-1+
blaSHV+
blaTEM-1+++
Beta-lactamase (class D)blaOXA-2+++15
blaOXA-7++
blaOXA-9+
Beta-lactamase (class C)blaACC-1+105
blaACC-2+
blaACT-1+++++
blaCMY+++
blaFOX+
blaMOX+++
blaMOX-CMY+
Chloramphenicol efflux pumpcmlA1 like+
Chloramphenicol acetyltransferasecatB8+
Erythromycin esteraseereB+++
DNA gyrase protection protein (quinolone)qnrB+
qnrS+
Modified dihydropteroate synthase (sulfonamide)sul1+
sul2++
Streptogramin acetyltransferasevatE+
Tetracycline efflux pumptetA+42
tetC+
tetD+
tetE+++
Modified dihydrofolate reductase (trimethoprim)dfr12+34
dfrA1+
dfrA7++
dfrA15+
dfrA17++
Total102110112453
  • a C, culture-based detection method (combined results for pooled isolates from each type of culture medium); I, integron-based detection method; +, gene or group of gene variants was detected. The shading indicates detection of a gene or related sequence by single-gene PCR and sequencing.

  • b Beta-lactamase class follows the Ambler classification system.