Environmental Science & Technology · 2010 · 782 citations · 36 references
Life SciencesMicrobiologyMolecular BiologyAntimicrobial ResistanceEnvironmental MicrobiologyMicrobial GeneticsAntibacterial ResistanceAntibiotic ResistanceAntibiotic Resistance GeneticsAntibiotic Resistance MechanismsResistance GenesSediment MicrobiologyAntibiotic Resistance GenesAntibiotic Resistance In The EnvironmentAntimicrobial Resistance Gene DetectionConcentrationQuantitative Pcr DetectionRelative Abundance AnalysisSulfonamide Resistance GenesTetracycline Resistance Genes
Class 1 integrons drive the spread of sulfonamide resistance genes, and their widespread environmental distribution poses public‑health risks that warrant better mitigation. The study quantified antibiotics and ARGs in water and sediment along a 72‑km stretch of the Haihe River, China. Tetracycline resistance genes were largely absent, whereas sul1 and sul2 were abundant—up to 1.7 × 10¹¹ copies g⁻¹ in summer sediments—often 120–2000 × higher than in water, and their abundance positively correlated with sulfonamide concentrations, indicating selective pressure.
The occurrence of antibiotics and antibiotic resistance genes (ARGs) was quantified in water and sediment samples collected from a 72 km stretch of the Haihe River, China. Tetracycline resistance genes (tetW, tetQ, tetO, tetT, tetM, tetB, and tetS) were not detected by quantitative PCR in many samples. In contrast, sul1 and sul2 (coding for sulfonamide resistance) were present at relatively high concentrations in all (38) samples. The highest ARG concentrations detected were (7.8 ± 1.0) × 10(9) copies/g for sul1 and (1.7 ± 0.2) × 10(11) copies/g for sul2, in sediment samples collected during the summer. The corresponding total bacterial concentration (quantified with a universal 16S-rDNA probe) was (3.3 ± 0.4) × 10(12) cells/g. Sul1 and sul2 concentrations in sediments were 120-2000 times higher than that in water, indicating that sediments are an important ARG reservoir in the Haihe River. Statistical analysis indicated a positive correlation between the relative abundance of these ARGs (i.e., sul1/16S-rDNA and sul2/16S-rDNA) and the total concentration of sulfamethoxazole, sulfadiazine, plus sulfachlororyridazine, suggesting that sulfonamides exerted selective pressure for these ARGs. A class 1 integron was implicated in the propagation of sul1. Overall, the widespread distribution of sulfonamide ARGs underscores the need to better understand and mitigate their propagation in the environment and the associated risks to public health.
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