The profile of antibiotics resistance and integrons of extended-spectrum beta-lactamase producing thermotolerant coliforms isolated from the Yangtze River basin in Chongqing

Class 1 and 2 integrons, sul resistance genes and antibiotic resistance in Escherichia coli isolated from Dongjiang River, South China

“…This may indicate much stronger selective pressure on bacteria in the Dongjiang River catchment. In addition, it is consistent with previous studies (Chen et al, 2010;Cocchi et al, 2007;Laroche et al, 2009;Skurnik et al, 2006) that only class 1 and 2 integrons were detected, without detection of class 3 integron in the present study since class 3 integron is rare even in animal and clinical samples. The sul1 gene is found associated with class 1 integrons (Vinue et al, 2010).…”

“…4). In the present study, 85.7% of isolates were integron-positive and the detection frequency is much higher than those reported values from previous surface water studies in other regions, for instance, 11% in France (Laroche et al, 2009), 15% in the Czech Republic (Dolejska et al, 2009), 29.6% in Portugal (Henriques et al, 2006), and 65.2% in Chongqing, China (Chen et al, 2010). The results suggest that surface water shows real-time status of contamination as described by Takasu et al (2011).…”

“…In our study, aadA2-lnuF, dfrA12-orfF-aadA2 and aar-3-dfrA27-aadA16 were 1.9 kb; aadA2 and dfrA7 were 0.7 kb. In the present study a much higher number of different ARGs were identified than in previous reports on surface water (Chen et al, 2010;Dolejska et al, 2009;Laroche et al, 2009;Henriques et al, 2006). Chen et al (2010) found that dfrA17-aadA5 was the most common gene cassette.…”

“…Most of the isolates only contained class 1 gene cassettes (79.6%), and 2.7% were found carrying both class 1 and 2 gene cassettes simultaneously. These frequencies were much higher than those reported from the Yangtze River (Chen et al, 2010), suggesting that Dongjiang River catchment is seriously contaminated by ARGs. In the Dongjiang River, 14 gene cassette arrays and 21 genes of 10 different families of resistance genes were found.…”

“…Previous investigations showed prevalence of antibiotic resistance, integrons and ARGs on surface water in the United States (Storteboom et al, 2010), France (Laroche et al, 2009), Portugal (Henriques et al, 2006), Czech Republic (Dolejska et al, 2009), Korea (Kim et al, 2008), Vietnam (Hoa et al, 2008;Phan et al, 2011;Takasu et al, 2011), Thailand (Takasu et al, 2011), India (Kumar et al, 2010), and Yangtze River, China (Chen et al, 2010). The spreading of multiple resistance bacteria such as E. coli in aquatic environments, especially in drinking water source, is also a threat to human health.…”