Fluoroquinolone (FQ) Contamination Does Not Correlate with Occurrence of FQ-Resistant Bacteria in Aquatic Environments of Vietnam and Thailand

Abstract

Fluoroquinolone antibiotics (FQs) have been used worldwide for chemotherapy, animal husbandry, and aquaculture, and the occurrence of FQ-resistant (FQs r ) bacteria in natural environments has been reported. Plasmid-mediated transferable quinolone resistance (PMQR) genes are suspected to originate from the chromosomes of water-dwelling bacteria. However, the occurrence of and the potential reservoir of FQs r bacteria and PMQR genes in aquatic environments have not been elucidated. In this study, we detected FQs r bacteria and PMQR genes in aquatic environments in Thailand and Vietnam, and measured FQ contamination. Levels of contamination were greater Thailand (avg. 5130, max 46100 ng L −1 ) than in Vietnam (avg. 235, max 1130 ng L −1 ); however, the occurrence of FQs r bacteria was higher in Vietnam (~15%) than in Thailand (~7.0%), suggesting that contamination by FQs is not directly linked to the development of FQs r bacteria. Diverse taxonomic groups of FQs r -bacteria were identified, and one of the PMQR genes, qnrB, was detected from bacteria of environmental origin, not enteric bacteria. This suggests that the environmental bacteria are a potential reservoir of antibiotic resistance determinants even at un-contaminated sites.

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

“…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). The incidence of integrons in the present study is even higher than those of clinical specimens, such as 40% in Spain (Vinue et al, 2010), 52% in Taiwan (Chang et al, 2000), 59.9% in Shanghai, China (Gu et al, 2008).…”

“…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.…”

Antibiotics, Antibiotic Resistance Genes, and Bacterial Community Composition in Fresh Water Aquaculture Environment in China

“…Given no antimicrobials used for therapeutic and prophylactic purpose in these fish ponds, these antibiotics were probably introduced by terrestrial animal wastes containing antibiotics. In integrated fish ponds receiving animal manure in Vietnam, the concentrations of sulfamethoxazole and sulfamethazine were reported in the range of 68.2-625 and 6.78-6662 ng L −1 , respectively [14]; the concentration of norfloxacin was as high as 43.1 ng L −1 , while ciprofloxacin was not observed [30]. The difference of antibiotic concentrations between these above studies and the present study indicated that the concentrations of antibiotics in fish ponds are dependent on the antibiotic consumption and application patterns in different geographical areas.…”

“…Some members of these taxonomic groups belonged to antibiotic resistance bacteria, which have been isolated from aquaculture environment. For example, (fluoro)quinolone-resistant bacteria belonged to diverse taxonomic groups, among which Proteobacteria and Actinobacteria were most abundant in fish ponds [30]. Among sulfamethoxazole-resistant strains from fish ponds, Acinetobacter was the most abundant (35 %), and all of them possessed sulfonamide resistance genes [14], and among oxytetracycline-resistant bacteria from aquaculture sources, one or more tetracycline resistance genes were detected at the percentage of 75 % [44].…”

“…For example, Acinetobacter posed resistance to sulfamethoxazole and tetracycline [16]; Escherichia and Acinetobacter were resistant to fluoroquinolones [30]. These genera closely related to human pathogens may enhance the probability of transferring antibiotic resistance to human pathogens, because horizontal gene transfer is more prevalent among closely related organisms than among those at phylogenetical distance [48].…”