Adsorption, natural attenuation, and microbial community response of ofloxacin and oxolinic acid in marine sediments.

The pollution of quinolone antibiotics in the marine environment has attracted widespread attention, especially for ofloxacin (OFL) and oxolinic acid (OXO) due to their frequent detection. However, few studies have been conducted to assess the behaviors and microbial community response to these antibiotics in marine sediments, particularly for potential antibiotic-resistant bacteria. In this work, the adsorption characteristics, natural attenuation characteristics, and variation of microbial communities of OFL and OXO in marine sediments were investigated. The adsorption process of antibiotics in sediments occurred on the surface and internal pores of organic matter, where OFL was more likely to be transferred from seawater to sediment compared with OXO. Besides, the adsorption of two antibiotics on sediment surfaces was attributed to physisorption (pore filling, electrostatic interaction) and chemisorption (hydrogen bonding). The natural attenuation of OFL and OXO in marine sediment followed second-order reaction kinetics with half-lives of 6.02 and 26.71 days, respectively, wherein biodegradation contributed the most to attenuation, followed by photolysis. Microbial community structure in marine sediments exposure to antibiotics varied by reducing abundance and diversity of microbial communities, as a whole displaying as an increase in the relative abundance of Firmicutes whereas a decrease of Proteobacteria. In detail, Escherichia-Shigella sp., Blautia sp., Bifidobacterium sp., and Bacillus sp. were those antibiotic-resistant bacteria with potential ability to degrade OFL, while Bacillus sp. may be resistant to OXO. Furthermore, functional predictions indicated that the microbial communities in sediment may resist the stress caused by OFL and OXO through cyano-amino acid metabolism, and ascorbate and aldarate metabolism, respectively. The research is key to understanding fate and bacterial resistance of antibiotics in marine sediments.

Survey of canine tick-borne diseases in Lábrea, Brazilian Amazon: ‘accidental’ findings of Dirofilaria immitis infection / Pesquisa de agentes transmitidos por carrapatos em cães de Lábrea, Amazonas: achados “acidentais” de Dirofilaria immitis

Blood samples were collected from 99 domestic dogs from the urban and rural areas of the Lábrea municipality, state of Amazonas, Brazil. Canine serum samples were tested by immunofluorescence assay against Rickettsia spp., which revealed that only 3.0% (1/33) and 7.6% (5/66) of the dogs from urban and rural areas, respectively, reacted positively to at least one Rickettsia species. DNA was extracted from canine blood and tested by a battery of PCR assays targeting protozoa of the genera Babesia and Hepatozoon, and bacteria of the genera Rickettsia and Ehrlichia and family Anaplasmataceae. All samples were negative in the PCR assays targeting the genera Babesia, Hepatozoon, Ehrlichia and Rickettsia. For Anaplasmataceae, 3% (1/33) and 39.4% (26/66) of the urban and rural dogs, respectively, yielded amplicons that generated DNA sequences 100% identical to the corresponding sequence of Wolbachia endosymbiont of Dirofilaria immitis. Because of these results, all canine DNA samples were further tested in a PCR assay targeting filarial nematodes, which was positive for 18.2% (6/33) and 57.6% (38/66) urban and rural dogs, respectively. Filarial-PCR products generated DNA sequences 100% identical to D. immitis. While tick-borne infections were rare in Lábrea, D. immitis infection rates were among the highest reported in South America.

Amostras de sangue foram coletadas de 99 cães domésticos de áreas urbana e rural do município de Lábrea, estado do Amazonas. Soros caninos foram testados pela técnica de imunofluorescência indireta contra Rickettsia spp., resultando em apenas 3,0% (1/33) e 7,6% (5/66) de cães soropositivos nas áreas urbana e rural, respectivamente. DNA foi extraído do sangue canino e testado por diferentes protocolos da PCR para detecção de protozoários dos gêneros Babesia e Hepatozoon, e bactérias dos gêneros Rickettsia e Ehrlichia e da família Anaplasmataceae. Todas as amostras foram negativas nos protocolos de PCR para os gêneros Babesia, Hepatozoon, Ehrlichia e Rickettsia. Para Anaplasmataceae, 3% (1/33) e 39,4% (26/66) dos cães de áreas urbana e rural, respectivamente, geraram sequências de DNA 100% idênticas ao endosimbionte Wolbachia de Dirofilaria immitis. Posteriormente, as amostras foram testadas pela PCR para nematódeos filarídeos, resultando em 18,2% (6/33) e 57,6% (38/66) de amostras positivas nas áreas urbana e rural, respectivamente. Os produtos geraram sequências de DNA 100% idênticas a D. immitis. Em contraste com várias outras regiões do Brasil, infecções transmitidas por carrapatos foram raras em Lábrea. Por outro lado, as frequências de infecção por D. immitis estiveram entre as mais altas relatadas na América do Sul.

Residuos de tetraciclina y quinolonas en peces silvestres en una zona costera donde se desarrolla la acuicultura del salmón en Chile / Residues of tetracycline and quinolones in wild fish living around a salmon aquaculture center in Chile

La presencia de antibacterianos y antiparasitarios residuales fue investigada en muestras de carne de peces silvestres de consumo humano pescados alrededor de un recinto de acuicultura en Cochamó (41° 29' S; 72° 19'W), X Región, Chile. Esta investigación demostró que peces silvestres, incluyendo róbalo (Elginops maclovinus), cabrilla (Sebastes capensis) y truchas de vida libre (Oncorhynchus mykiss), ingieren alimento artificial para salmón y que la carne de algunos ejemplares de estos peces contienen tetracicilina y quinolona en cantidades detectables. Estos resultados sugieren que el uso de antibacterianos en la acuicultura del salmón, como ha sido demostrado en otros países, tiene efectos ambientales que se proyectan más allá de los recintos de acuicultura. Se indica que dada la relevancia de estos hallazgos para la salud humana y animal, el ambiente requerirá de estudios más amplios y detallados para implementar futuras regulaciones del uso de antibacterianos en acuicultura.

The presence of residues of tetracycline, quinolones and antiparasitic drugs was investigated in wild fish captured around salmon aquaculture pens in Cochamó, Region X, Chile. Residues of both antibiotics were found in the meta of two species of wild fish that are consumed by humans, robalo (Elginops maclovinus) and cabrilla (Sebastes capensis) . These findings suggest that the antibiotic usage in salmon aquaculture in Chile has environmental implications that may affect human and animal health. More studies are needed in Chile to determine the relevance of these findings for human and animal health and the environment to regulate this use of antibiotics.