Occurrence of extended-spectrum beta-lactamase (ESBL) and carbapenemases among ampicillin-resistant enterobacteriales recovered from a municipal raw sewage in Minas Gerais, Brazil

SUMMARY Introduction: The capacity of resistance to ß-lactam among enterobacteriales is notable, mainly into water environment. Herein, many species of this family have the ability to carrier and produce ß-lactamases enzymes, such as extended-spectrum ß-lactamases (ESBLs) and carbapenemases. However, contrary to clinical settings, where the distribution of resistant bacteria is well documented, the evidence of resistant pathogens in the domestic sewage has been little explored, especially in Brazil. Thus, we aimed to investigate the occurrence of ESBL and carbapenemases between ampicillin-resistant enterobacteriales recovered from a municipal raw sewage in Minas Gerais, Brazil. Methods: Enterobacteriales were isolated from sewage samples on MacConkey agar supplemented with ampicillin. Species identification was performed by biochemical and morphological methods and the resistance profile determined by the Kirby-Bauer test. The production of ESBL and carbapenemase was investigated in all isolates by phenotypic tests. Results and discussion: A total of 45 species of enterobacteriales resistant to ampicillin were recovered (37 Escherichia coli, four Klebsiella pneumoniae, and one Klebsiella oxytoca, Citrobacter freundii and Pantoea agglomerans). Most isolates showed a high ß-lactam susceptibility profile (14/45, 31.1 %), however E. coli with decreased susceptibility to imipenem was detected (2/37; 2.7 %). ESBL-positive isolates were mostly identified as E. coli (10/45; 22.2 %), but no isolates were positive carbapenemase. Conclusion: Domestic sewage is an important source of ß-lactams resistant determinants in Brazil.

Introdução: a capacidade de resistência aos beta-lactâmicos entre enterobacteriales é notável, principalmente no ambiente aquático. Nessa direção, muitas espécies desta família têm a capacidade de transportar e produzir enzimas ß-lactamases, especialmente a ß-lactamases de espectro estendido (ESBL) e as carbapenemases. Porém, ao contrário do cenário clínico, onde a distribuição de bactérias resistentes é bem documentada, as evidências de patógenos resistentes no esgoto doméstico têm sido pouco exploradas, principalmente no Brasil. Assim, objetivamos investigar a ocorrência de ESBL e carbapenemases entre enterobacteriales resistentes à ampicilina recuperadas de um esgoto bruto municipal em Minas Gerais, Brasil. Métodos: enterobacteriales foram isoladas de amostras de esgoto em ágar MacConkey suplementado com ampicilina. A identificação das espécies foi realizada por métodos bioquímicos e morfológicos e o perfil de resistência determinado pelo teste de Kirby-Bauer. A produção de ESBL e carbapenemase foi investigada em todos os isolados por testes fenotípicos. Resultados e discussão: foram recuperadas 45 isolados de enterobacteriales resistentes à ampicilina (37 Escherichia coli, quatro Klebsiella pneumoniae e uma Klebsiella oxytoca, Citrobacter freundii e Pantoea agglomerans). A maioria dos isolados apresentou um perfil de alta susceptibilidade aos ß-lactâmicos (14/45, 31,1 %), porém E. coli com susceptibilidade diminuída ao imipenem foi detectada (2/37; 2,7 %). Os isolados ESBL-positivos foram identificados principalmente como E. coli (10/45; 22,2 %), mas nenhum isolado foi positivo para a carbapenemase. Conclusão: o esgoto doméstico é uma importante fonte de determinantes de resistência aos ß-lactâmicos no Brasil.

Introducción: la capacidad de resistencia a betalactámicos entre enterobacteriales es notable, principalmente en el medio acuático. En este sentido, muchas especies de esta familia tienen la capacidad de transportar y producir enzimas ß-lactamasas, especialmente ß-lactamasas de espectro extendido (BLEE) y carbapenemasas. Sin embargo, en contraste con el escenario clínico, donde la distribución de bacterias resistentes está bien documentada, la evidencia de patógenos resistentes en las aguas residuales domésticas ha sido poco explorada, especialmente en Brasil. Por lo tanto, nuestro objetivo es investigar la ocurrencia de BLEE y carbapenemasas entre enterobacteriales resistentes a ampicilina recuperadas de un alcantarillado municipal sin tratar en Minas Gerais, Brasil. Métodos: se aislaron enterobacteriales de muestras de aguas residuales en agar MacConkey suplementado con ampicilina. La identificación de las especies se realizó mediante métodos bioquímicos y morfológicos y el perfil de resistencia se determinó mediante la prueba de Kirby-Bauer. La producción de BLEE y carbapenemasa se investigó en todos los aislamientos mediante pruebas fenotípicas. Resultados y discusión: se recuperaron 45 aislamientos de enterobacteriales resistentes a ampicilina (37 Escherichia coli, cuatro Klebsiella pneumoniae y una Klebsiella oxytoca, Citrobacter freundii y Pantoea agglomerans). La mayoría de los aislamientos tenían un perfil de susceptibilidad alto a los (3-lactámicos (14/45, 31,1 %), pero se detectó E. coli con susceptibilidad reducida al imipenem (2/37; 2,7 %). Los aislamientos positivos para BLEE se identificaron principalmente como E. coli (10/45; 22,2 %), pero ningún aislado fue positivo para carbapenemasa. Conclusión: las aguas residuales domésticas son una fuente importante de determinantes de la resistencia a los ß-lactámicos en Brasil.

Efficient cutaneous wound healing using bixin-loaded PCL nanofibers in diabetic mice.

The present work demonstrated an efficient cutaneous wound healing using Bixin-loaded polycaprolactone (PCL) nanofibers as a controlled delivery system. The influence of Bixin (Bix) content on PCL nanofiber, Bix-PCL1(2.5% w/w bix) and Bix-PCL2 (12.5% w/w bix) formation was investigated using electrical conductivity, attenuated total reflectance infrared spectroscopy, X-ray diffraction, thermal analysis, and scanning electronic microscopy. The results showed that a greater bixin concentration resulted in higher polymeric solution electrical conductivity. Moreover, higher polymeric solution electrical conductivity provides lower nanofibers in terms of average diameter than pure PCL nanofibers. In vitro release was largely governed by a diffusion-controlled mechanism. The initial Bixin release domain showed a burst release over the first 10 hours where approximately 30% and 40% of Bixin was released from Bix-PCL1 and Bix-PCL2 nanofibers, respectively. The second kinetic domain was comprised of a continuous and slow Bixin release that led to almost 100% of the Bixin being released within 14 days. The results on excisional wound model in induced diabetic mice indicated that the low concentration of Bixin released from loaded Bix-PCL nanofibers maintain the biological activity of Bixin and is efficient in accelerating the wound healing as well as in reducing the scar tissue area compared with pure PCL nanofibers. Therefore, soft material Bixin-loaded PCL nanofibers are a promising candidate for use in wound dressing. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1938-1949, 2017.

The effect of cyclodextrins on the in vitro and in vivo properties of insulin-loaded poly (D,L-lactic-co-glycolic acid) microspheres.

In this work we describe the development and characterization of a new formulation of insulin (INS). Insulin was complexed with cyclodextrins (CD) in order to improve its solubility and stability being available as a dry powder, after encapsulation into poly (D,L-lactic-co-glycolic acid) (PLGA) microspheres. The complex INS : CD was encapsulated into microspheres in order to obtain particles with an average diameter between 2 and 6 microm. This system was able to induce significant reduction of the plasma glucose level in two rodent models, normal mice and diabetic rats, after intratracheal administration.