Occurrence and ecological hazard assessment of selected veterinary medicines in livestock wastewater treatment plants.

The occurrence of some veterinary medicines in the livestock wastewater plants (WWTPs) was investigated. This investigation represented the occurrence of veterinary medicines to treat in the livestock WWTPs or be discharged into the water system in Korea since the sampling sites were widely distributed across the nation and samples were collected from the 11 livestock WWTPs. Nine antibiotics, two analgesics, and two disinfectants occurred in the livestock wastewater plants (WWTPs). From 11 livestock WWTP influents, chlortetracycline, oxytetracycline, acetylsalicylic acid, and disinfectants frequently occurred with the high concentrations. Meanwhile, sulfamethoxazole, erythromycin-H2O, and trimethoprim did not occur during sampling periods. The values for log Kow of each chemical showed a high correlation with the number of hydrogen bonding acceptors and were important parameters to estimate and understand the biodegradability and toxicity of a compound in the environment. The biodegradability of each compound was proportional to the hydrophilicity of each compound and the toxicity was proportional to the number of hydrogen bonding acceptors of each compound. The expected introductory concentration (EIC), predicted exposure concentration (PEC), and hazard quotient showed that the livestock WWTP effluents were hazardous to ecosystems.

Antibiotic resistance in bacteria isolated from freshwater aquacultures and prediction of the persistence and toxicity of antimicrobials in the aquatic environment.

The occurrence of antibiotic-resistant bacteria isolated from freshwater aquaculture effluents was investigated. The bacterial strains were collected from four different freshwater aquaculture effluents (catfish, trout, eel, and loach). Based on sequence of 16S rRNA, a total of 20 bacterial strains was isolated and one half of the isolated bacteria were Aeromonas sp. The antimicrobial sensitivity test was performed using the disc diffusion method. Individual antibiotic-resistant bacteria to antimicrobials were 41.7% and multiple antibiotic resistant bacteria were 58.3%. The disinfection of antibiotic-resistant bacteria by electron beam (E-beam) irradiation was carried out using an electron accelerator. Antibiotic-resistant bacteria were effectively disinfected by E-beam irradiation. The isolated bacteria were completely disinfected at a dose of less than 2 kGy. The persistence and toxicity of each antimicrobial in the aquatic environment was estimated due to the human health and ecosystems. In order to estimate the persistence and toxicity of antimicrobials in the aquatic environment, two quantitative structure activity relationship (QSAR) models were used. The persistence and toxicity of each antimicrobial were influenced on its hydrophobicity. In addition, QSAR models showed that isoelectric point and hydrogen bonding acceptor are key parameters to estimate the persistence and toxicity of antimicrobials in the aquatic environment.

The effect of photodynamic therapy with rose bengal on posterior capsule opacification in rabbit eyes.

We investigated the in vivo effect of photodynamic therapy (PDT) using rose bengal on the development of posterior capsule opacification (PCO). Endocapsular phacoemulsification was performed on white rabbits, which were divided into 4 groups: control group; group 1, treated with visible light only; group 2, treated with rose bengal only, and group 3, treated with PDT. In the case of the PDT group, rose bengal dissolved in sodium hyaluronate was injected into the empty capsular bag and treated with visible light. Three months after surgery, the rabbits were sacrificed and the eyeballs enucleated. The obstruction rate of visible light caused by PCO was measured with an optical powermeter. The mean obstruction rate was 30.6% in the control group, 28.3% in group 1, 19.3% in group 2, and 14.3% in group 3. Group 3 showed a statistically significant decrease in PCO compared with the control group and group 1 (p = 0.0014). Our results suggest that PDT using rose bengal effectively decreased PCO in rabbit eyes.