Development of a Mosquito Repellent Formulation Based on Nanostructured Lipid Carriers.

Arboviral diseases are a threat to global public health systems, with recent data suggesting that around 40% of the world's population is at risk of contracting arboviruses. The use of mosquito repellents is an appropriate strategy to avoid humans coming into contact with vectors transmitting these viruses. However, the cost associated with daily applications of repellents can make their use unfeasible for the low-income populations that most need protection. Therefore, the development of effective formulations offers a way to expand access to this means of individual protection. Consequently, research efforts have focused on formulations with smaller quantities of active agents and sustained release technology, aiming to reduce re-applications, toxicity, and cost. The present study investigates the development of nanostructured lipid carriers (NLCs) loaded with a mixture of the compounds icaridin (synthetic) and geraniol (natural), incorporated in cellulose hydrogel. The NLCs were prepared by the emulsion/solvent evaporation method and were submitted to physicochemical characterization as a function of time (at 0, 15, 30, and 60 days). The prepared system presented an average particle size of 252 ± 5 nm, with encapsulation efficiency of 99% for both of the active compounds. The stability profile revealed that the change of particle size was not significant (p > 0.05), indicating high stability of the system. Rheological characterization of the gels containing NLCs showed that all formulations presented pseudoplastic and thixotropic behavior, providing satisfactory spreadability and long shelf life. Morphological analysis using atomic force microscopy (AFM) revealed the presence of spherical nanoparticles (252 ± 5 nm) in the cellulose gel matrix. Permeation assays showed low fluxes of the active agents through a Strat-M® membrane, with low permeability coefficients, indicating that the repellents would be retained on the surface to which they are applied, rather than permeating the tissue. These findings open perspectives for the use of hybrid formulations consisting of gels containing nanoparticles that incorporate repellents effective against arthropod-borne virus. These systems could potentially provide improvements considering the issues of effectiveness, toxicity, and safety.

Contaminação ambiental e perfil toxigênico de Bacillus cereus isolados em serviços de alimentação / Environmental contamination and enterotoxigenic profile of Bacillus cereus isolated in food services

A avaliação da contaminação ambiental por Bacillus cereus foi realizada em 90 amostras de ar ambiente e em 96 amostras de superfícies de bancadas e de equipamentos, de dois restaurantes institucionais. O microrganismo foi detectado em 84,4% e 44,8% das amostras de ar ambiente e de superfícies, respectivamente. O potencial enterotoxigênico dos isolados foi investigado através da reação da polimerase em cadeia (PCR) para os genes hblA, hblD e hblC (que codificam a hemolisina BL) e para os genes nheA, nheB e nheC (que codificam a enterotoxina não hemolítica - NHE). De um total de 70 isolados investigados, 14,3% foram positivos para os três genes da HBL e 12,8% foram positivos para os três genes da NHE. A produção de NHE também foi verificada através do Bacillus Diarrhoeal Enterotoxin Visual Immunoassay (kit BDE-VIA; Tecra). Os resultados obtidos com o kit revelaram que 61,4% dos 70 isolados são produtores de NHE(AU)

Ninety air samples and ninety six samples from benches and equipments surfaces were collected in two food services for investigation of Bacillus cereus contamination sources and characterization of strains toxin profiles. B. cereus was detected in 84.4% and 44.8% from air samples and samples from benches and equipments surfaces, respectively. The potential of enterotoxin production was investigated using polymerase chain reaction (PCR) methods for genes hblA, hblD e hblC (encoding hemolysin BL) and for genes nheA, nheB and nheC (encoding non-hemolytic enterotoxin - NHE). From 70 isolates investigated 14.3% were positive for the three HBL encoding genes and 12.8% were positive for the three NHE encoding genes. The Bacillus Diarrhoeal Enterotoxin Visual Immunoassay (BDE-VIA; Tecra) also was used for NHE detection. The results obtained with BDE-VIA revealed that 61.4% from the 70 strains are NHE producers(AU)

Contaminação ambiental e perfil toxigênico de Bacillus cereus isolados em serviços de alimentação / Environmental contamination and enterotoxigenic profile of Bacillus cereus isolated in food services

A avaliação da contaminação ambiental por Bacillus cereus foi realizada em 90 amostras de ar ambiente e em 96 amostras de superfícies de bancadas e de equipamentos, de dois restaurantes institucionais. O microrganismo foi detectado em 84,4 por cento e 44,8 por cento das amostras de ar ambiente e de superfícies, respectivamente. O potencial enterotoxigênico dos isolados foi investigado através da reação da polimerase em cadeia (PCR) para os genes hblA, hblD e hblC (que codificam a hemolisina BL) e para os genes nheA, nheB e nheC (que codificam a enterotoxina não hemolítica - NHE). De um total de 70 isolados investigados, 14,3 por cento foram positivos para os três genes da HBL e 12,8 por cento foram positivos para os três genes da NHE. A produção de NHE também foi verificada através do Bacillus Diarrhoeal Enterotoxin Visual Immunoassay (kit BDE-VIA; Tecra). Os resultados obtidos com o kit revelaram que 61,4 por cento dos 70 isolados são produtores de NHE.

Ninety air samples and ninety six samples from benches and equipments surfaces were collected in two food services for investigation of Bacillus cereus contamination sources and characterization of strains toxin profiles. B. cereus was detected in 84.4 percent and 44.8 percent from air samples and samples from benches and equipments surfaces, respectively. The potential of enterotoxin production was investigated using polymerase chain reaction (PCR) methods for genes hblA, hblD e hblC (encoding hemolysin BL) and for genes nheA, nheB and nheC (encoding non-hemolytic enterotoxin - NHE). From 70 isolates investigated 14.3 percent were positive for the three HBL encoding genes and 12.8 percent were positive for the three NHE encoding genes. The Bacillus Diarrhoeal Enterotoxin Visual Immunoassay (BDE-VIA; Tecra) also was used for NHE detection. The results obtained with BDE-VIA revealed that 61.4 percent from the 70 strains are NHE producers.

Virulence factors of Escherichia coli isolated from calves with diarrhea in Brazil

Duzentas e cinco amostras de Escherichia coli isoladas de bezerros com diarréia da região centro oeste do Brazil foram examinados quanto a presenca de fatores de virulência associados à colibacilose bovina. Cento e duas amostras (49,8 per center) de E. coli produziram toxinas: toxina de Shiga do tipo 1 (9,7 per center) e 2 (6,3 per center), a-hemolisina (9,7 per center), enterohemolisina (6,8 per center), Fatores Citotóxicos Necrotisantes tipo 1 (0,5 per center) e 2 (4,4 per center), enterotoxinas LT-II (8,3 per center), e STa (3,9 per center). Nenhuma amostra produziu enterotoxina LT-I. Adesinas fimbriais F5 e F17 foram produzidas por 7,3 per center e 4,8 per center das cepas, respectivamente, e nenhuma expressou F41. Sete das amostras (3,4 per center) apresentaram o gene eae e pertenceram aos sorotipos O26:H-; O111:H- e O118:H16. Estes resultados sugerem que bezerros no Brasil podem ser uma importante fonte de E. coli patogênica para animais e humanos.