Abstract
We evaluated the occurrence of antibiotic-resistant bacteria, antibiotic-resistant gene, and metal concentration in a tropical river of Sri Lanka as a pre-emptive effort to understand the seasonal impact on their prevalence. Resistance for norfloxacin, ciprofloxacin, levofloxacin, kanamycin monosulfate (KM), tetracycline (TC), and sulfamethoxazole (ST) was measured with Kirby–Bauer disc diffusion method. The prevalence of Escherichia coli ranged from 10 to 27 CFU (colony-forming unit) ml−1 in Kelani River in Sri Lanka, and most of the E. coli isolates were resistant to more than one antibiotic. However, the resistance for TC and ST was much higher than other antibiotics. We found that the resistance percentage for older antibiotics like TC and ST was higher than the newer antibiotics. We detected genes that confer resistance to TCs, sulfonamides, β-lactams, and fluoroquinolones. Seasonal variation in the resistance of fluoroquinolones was much higher than the non-fluoroquinolones, but the effect was antagonistic. Overall, the significant seasonal variations imply the importance of mixed source and environmental conditions for development and transmission of antibiotic resistance.
Highlights
Antibiotic resistance and multidrug resistance are emerging environmental concern owing to its potential threat to human health, and fast-growing and widespread increase
We did not observe the large change in the range of prevalence of total coliform in October (23–31 CFU ml−1) and March (17–26 CFU ml−1), but the maximum number of E. coli isolated in October (27 CFU ml−1) was three times higher than in March (n = 9 CFU ml−1)
At the Seethawaka EPZ sampling point, a considerably higher E. coli prevalence was measured as compared to downstream sampling points, which probably suggests flushing of poorly treated industrial wastewater of Seethawaka EPZ
Summary
Antibiotic resistance and multidrug resistance are emerging environmental concern owing to its potential threat to human health, and fast-growing and widespread increase. Studies reported the increase of antibiotic-resistant gene (ARG)
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