BackgroundDuring evolution, innate immunity has been tuned to recognize pathogen-associated molecular patterns. However, some α-Proteobacteria are stealthy intracellular pathogens not readily detected by this system. Brucella members follow this strategy and are highly virulent, but other Brucellaceae like Ochrobactrum are rhizosphere inhabitants and only opportunistic pathogens. To gain insight into the emergence of the stealthy strategy, we compared these two phylogenetically close but biologically divergent bacteria.Methodology/Principal FindingsIn contrast to Brucella abortus, Ochrobactrum anthropi did not replicate within professional and non-professional phagocytes and, whereas neutrophils had a limited action on B. abortus, they were essential to control O. anthropi infections. O. anthropi triggered proinflammatory responses markedly lower than Salmonella enterica but higher than B. abortus. In macrophages and dendritic cells, the corresponding lipopolysaccharides reproduced these grades of activation, and binding of O. anthropi lipopolysaccharide to the TLR4 co-receptor MD-2 and NF-κB induction laid between those of B. abortus and enteric bacteria lipopolysaccharides. These differences correlate with reported variations in lipopolysaccharide core sugars, sensitivity to bactericidal peptides and outer membrane permeability.Conclusions/SignificanceThe results suggest that Brucellaceae ancestors carried molecules not readily recognized by innate immunity, so that non-drastic variations led to the emergence of stealthy intracellular parasites. They also suggest that some critical envelope properties, like selective permeability, are profoundly altered upon modification of pathogen-associated molecular patterns, and that this represents a further adaptation to the host. It is proposed that this adaptive trend is relevant in other intracellular α-Proteobacteria like Bartonella, Rickettsia, Anaplasma, Ehrlichia and Wolbachia.

Contribución de los autores:Lucía Quesada-Lobo realizó la documentación del caso, toma de muestras, revisión bibliográfica y fue la principal responsable de la redacción del texto. Adriana Troyo aportó en la identificación del material presentado, análisis crítico y revisión del documento. Ólger Calderón-Arguedas procesó, identificó y fotografió el material presentado, colaboró con la revisión bibliográfica, el análisis crítico y la redacción del documento. Introducción. Las miasis hospitalarias son entidades con una importancia manifiesta en salud pública. La documentación de este tipo de casos es escasa en la literatura biomédica regional y mundial. Objetivo. Informar un caso de miasis hospitalaria en Costa Rica, donde el agente etiológico implicado fue Lucilia cuprina (Diptera: Calliphoridae). Este caso de miasis hospitalaria figura como el primer informe para Latinoamérica asociado con este agente etiológico. Presentación del caso. Una paciente de 91 años de edad, con signos de inmunosupresión, afectación grave de la función pulmonar y asistencia respiratoria mecánica, presentó larvas en ambas fosas nasales al séptimo día después del ingreso hospitalario. Varios ejemplares fueron recolectados y procesados para su identificación. La identificación taxonómica de los ejemplares recolectados estableció que la especie de los muscomorfos correspondía a L. cuprina. Conclusión. El presente constituye el primer caso de miasis hospitalaria por L. cuprina en la literatura biomédica de Costa Rica y el primero registrado en Latinoamérica. Introduction. Nosocomial myiases can be an important condition from a public health perspective. However, cases of this condition reported in regional and worldwide biomedical literature are scarce. Objective. A case of nosocomial myiasis is reported from Costa Rica, where the species involved was Lucilia cuprina (Diptera: Calliphoridae). Materials and methods. A 91-year-old patient with signs of immunosuppression, severe impairment of lung function, and mechanical ventilation presented larvae in both nostrils on the seventh day after admission. Five specimens were collected and processed for identification. Results. The taxonomic identification of the specimens established that the muscoid fly species was L. cuprina. Conclusion. This is the first case of nosocomial myiasis reported from Costa Rica and in Latin America for which the etiological agent is L. cuprina. PRESENTACIÓN DE CASO