Presence of Stenotrophomonas maltophilia exhibiting high genetic similarity to clinical isolates in final effluents of pig farm wastewater treatment plants.

Although the prevalence of community-acquired Stenotrophomonas maltophilia infections is sharply increasing, the sources and likely transmission routes of this bacterium are poorly understood. We studied the significance of the presence of S. maltophilia in final effluents and receiving rivers of pig farm wastewater treatment plants (WWTPs). The loads and antibiotic resistance profiles of S. maltophilia in final effluents were assessed. Antibiotic resistance determinants and biofilm formation genes were detected by PCR, and genetic similarity to clinical isolates was investigated using multilocus sequence typing (MLST). S. maltophilia was recovered from final effluents at two of three farms and one corresponding receiving river. Tests of resistance to antibiotics recommended for S. maltophilia infection revealed that for each agent, at least one isolate was classified as resistant or intermediate, with the exception of minocycline. Furthermore, multidrug resistant S. maltophilia susceptible to antibiotics of only two categories was isolated and found to carry the sul2 gene, conferring trimethoprim/sulfamethoxazole resistance. All isolates carried spgM, encoding a major factor in biofilm formation. MLST revealed that isolates of the same sequence type (ST; ST189) were present in both effluent and receiving river samples, and phylogenetic analysis showed that all of the STs identified in this study clustered with clinical isolates. Moreover, one isolate (ST192) recovered in this investigation demonstrated 99.61% sequence identity with a clinical isolate (ST98) associated with a fatal infection in South Korea. Thus, the pathogenicity of the isolates reported here is likely similar to that of those from clinical environments, and WWTPs may play a role as a source of S. maltophilia from which this bacterium spreads to human communities. To the best of our knowledge, this represents the first report of S. maltophilia in pig farm WWTPs. Our results indicate that nationwide epidemiological investigations are needed to examine the possible link between WWTP-derived S. maltophilia and hospital- and community-acquired infections.

Thymidine kinase gene delivery using curcumin loaded peptide micelles as a combination therapy for glioblastoma.

PURPOSE: The effect of the combination therapy of curcumin and the herpes simplex virus thymidine kinase (HSVtk) gene using R7L10 as a carrier was evaluated in a glioblastoma animal model. METHODS: Curcumin was loaded into the cores of R7L10 peptide micelles using an oil-in-water emulsion/solvent evaporation method to generate curcumin loaded R7L10 micelles (R7L10-Cur), which were used as a carrier to deliver the HSVtk gene. The plasmid DNA (pDNA)/R7L10-Cur complex was confirmed by gel retardation, heparin competition, and dynamic light scattering analyses. Transfection efficiency and cytotoxicity were measured using luciferase, MTT, and TUNEL assays. Intracellular delivery of curcumin was determined by fluorescence and absorbance. In the glioblastoma animal model, the effects of the intratumoral delivery of curcumin and the HSVtk gene were evaluated according to tumor size, immunohistochemistry, and TUNEL assays. RESULTS: R7L10-Cur delivered pDNA into the cells more efficiently than PLL and R7L10. In addition, R7L10-Cur delivered curcumin into the cells more efficiently than curcumin alone. The pHSVtk/R7L10-Cur complex induced cell death efficiently both in vitro and in vivo. Likewise, the combination of curcumin and the HSVtk gene using the pHSVtk/R7L10-Cur complex reduced tumor size more efficiently than the pHSVtk/PEI and pHSVtk/R7L10 complexes in a glioblastoma animal model. CONCLUSION: R7L10 is an efficient carrier for delivery of curcumin and the HSVtk gene, which may be a useful combination therapy for glioblastoma.