RESUMEN
During the last few years, antibiotic multiresistance has been increasing, not only in hospitals, but also, more worryingly, in general medicine. Different ways are being explored to bypass this problem. RNA-acting antibiotics such as aminosides (aminoglycosides) bind to bacterial RNA causing premature termination of proteins and mistranslation in bacteria. It is now possible to study the interactions of such antibiotics with their target by in-vitro selection of RNA molecules that recognize these antibiotics (RNA aptamers, SELEX method). The knowledge of the antibiotic-RNA interactions represents a promising way for the rational design of new bioactive compounds less susceptible to bacterial resistance.
Asunto(s)
Antibacterianos/farmacología , Diseño de Fármacos , Resistencia a Múltiples Medicamentos , ARN/metabolismo , Aminoglicósidos , Antibacterianos/química , Bacterias/genética , Técnicas In VitroRESUMEN
Rambach agar and novobiocin-brilliant green-glycerol-lactose (NBGL) agar are two recently described media designed for Salmonella isolation. Rambach and NBGL agars were compared to usual media in human and veterinary routines, by evaluation of sensitivities and predictive values of suspect colonies. In the human routine, 4037 stools, sensitivities were 79% for Hektoen agar, 51% for Rambach agar and 96% for NBGL agar at the direct plating for a total of 94 strains; and 89%, 87% and 94% respectively at the plating of Mueller-Kauffmann enrichment broth for a total of 143 strains. Predictive values of suspect colonies were respectively 58%, 93%, 91% at the direct plating; and 25%, 74%, 80% at the plating of Mueller-Kauffmann enrichment broth. In the veterinary routine, 584 samples, sensitivity was 65% on the association of Salmonella-Shigella and Hektoen agars, 70% on Rambach agar and 85% on NBGL agar, for a total of 40 strains. Predictive values of suspect colonies were 7.4%, 82.3% and 83% respectively. These results showed that Rambach and NBGL agars have distinct properties, and are both highly predictive. The highest sensitivities were achieved by the NBGL agar.
Asunto(s)
Heces/microbiología , Novobiocina , Compuestos de Amonio Cuaternario , Salmonelosis Animal/diagnóstico , Infecciones por Salmonella/diagnóstico , Salmonella/aislamiento & purificación , Animales , Antiinfecciosos Locales , Medios de Cultivo , Glicerol , Humanos , Lactosa , Infecciones por Salmonella/microbiología , Salmonelosis Animal/microbiologíaRESUMEN
In order to provide a wider evaluation of "Novobiocin-brilliant green-glycerol-lactose" (NBGL) agar, dishes of this medium were added to standard media: Hektoen (H), Salmonella-Shigella agar (SS), at all plating steps for 5554 stool cultures of human medical routine (280 isolates) and 982 samples of veterinary routine (133 isolates). NBGL expectedly missed lactose-glycerol positive strains of the serotype Senftenberg (n = 4), H2S negative strains (n = 1), and strains of the Typhi serotype (n = 7). Otherwise, three strains, of serotype Virchow, were unable to grow on NBGL (0.7% of positive samples). Nevertheless overall sensitivities were increased by approximately 10% in the human routine (H: 70%; SS: 63%; NBGL: 94%; at the direct plating step) (H: 83%; SS: 84%; NBGL: 92%; at the enrichment plating step) and by 48% in the veterinary one (NBGL: 97%; versus usual media: 68%). Positive predictive values of black centred colonies were significantly higher on NBGL in human routine (H: 38%; SS: 40%; NBGL: 89%; at the direct plating step) (H: 20%; SS: 21%; NBGL: 82%; at the enrichment plating step); and in the veterinary one as well (NBGL: 90%; versus usual media: 17%). These data suggest that NBGL agar does improve Salmonella isolation in these kinds of routines, and that growth should be made sure before experiments using given strains.