Differential roles for pathogenicity islands SPI-13 and SPI-8 in the interaction of Salmonella Enteritidis and Salmonella Typhi with murine and human macrophages

BACKGROUND: Salmonella pathogenicity island (SPI)-13 is conserved in many serovars of S. enterica, including S. Enteritidis, S. Typhimurium and S. Gallinarum. However, it is absent in typhoid serovars such as S. Typhi and Paratyphi A, which carry SPI-8 at the same genomic location. Because the interaction with macrophages is a critical step in Salmonella pathogenicity, in this study we investigated the role played by SPI-13 and SPI-8 in the interaction of S. Enteritidis and S. Typhi with cultured murine (RAW264.7) and human (THP-1) macrophages. RESULTS: Our results showed that SPI-13 was required for internalization of S. Enteritidis in murine but not human macrophages. On the other hand, SPI-8 was not required for the interaction of S. Typhi with human or murine macrophages. Of note, the presence of an intact copy of SPI-13 in a S. Typhi mutant carrying a deletion of SPI-8 did not improve its ability to be internalized by, or survive in human or murine macrophages. CONCLUSIONS: Altogether, our results point out to different roles for SPI-13 and SPI-8 during Salmonella infection. While SPI-13 contributes to the interaction of S. Enteritidis with murine macrophages, SPI-8 is not required in the interaction of S. Typhi with murine or human macrophages. We hypothesized that typhoid serovars have lost SPI-13 and maintained SPI-8 to improve their fitness during another phase of human infection.

Infecciones vaginales en un Centro de Salud Familiar de la Región Metropolitana, Chile / Vaginal infections in a Family Health Clinic in the Metropolitan Region, Chile

Background: Vaginal infections are a frequent cause for consultation, but their prevalence and etiology vary in different populations. Objectives: To determine the prevalence and etiologies of vaginal infection in women attending a family health center in the Metropolitan Region of Chile. Methods: The microbiological diagnosis was made by wet mount and Gram stain. Diagnosis of trichomoniasis was performed by wet mount, culture and polymerase chain reaction. Results: 101 women aged 15-54, not selected by signs or symptoms of vaginal infection, 46 of them pregnant were included. In 47 women (46.5%), vaginal infections were diagnosed. An association was observed between age and frequency of vaginal infection. The proportion of infections among pregnant and non-pregnant women was similar. The most frequent infections were bacterial vaginosis (16.8%), vulvovaginal candidiasis (11.9%) and co-infections (6.9%). We found 5.9% of intermediate microbiota cases, 3% of trichomoniasis and 2% of aerobic vaginitis. Symptoms of vaginal infection had poor agreement with microbiological findings. Otherwise physical signs had good agreement with the presence of infection, but low to moderate concordance with a specific etiology. Conclusions: We found a high prevalence of vaginal infections in the study population. It is necessary to improve the definitions and criteria of microbiological diagnosis of co-infections and intermediate microbiota, for them to be diagnosed in the clinical practice. More descriptive questionnaires are recommended to enhance the usefulness of clinical examination.

Introducción: Las infección vaginales constituyen un motivo frecuente de consulta, pero su prevalencia y etiología varían en distintas poblaciones. Objetivos: Determinar la prevalencia y tipos de infección vaginal en mujeres atendidas en un centro de salud familiar de la Región Metropolitana. Métodos: El diagnóstico microbiológico fue efectuado mediante examen microscópico al fresco y tinción de Gram y para tricomoniasis examen al fresco, cultivo y reacción de la polimerasa en cadena. Resultados: Se incluyeron 101 mujeres de 15-54 años, no seleccionadas por signos ó síntomas, 46 de ellas embarazadas. En 47 mujeres (46,5%) se diagnosticaron infecciones vaginales. Se observó asociación entre edad y frecuencia de infección vaginal. La proporción de infecciones entre gestantes y no gestantes fue similar. Las infecciones más frecuentes fueron vaginosis bacteriana (16,8%), candidiasis vulvo-vaginal (11,9%) y co-infecciones (6,9%). Se observó 5,9% casos de microbiota intermedia, 3% de tricomoniasis y 2% de vaginitis aeróbica. Los síntomas de infección vaginal tuvieron mala concordancia con los hallazgos microbiológicos. A su vez, los signos físicos tuvieron buena concordancia con la existencia de infección, pero escasa a moderada concordancia con una etiología específica. Conclusiones: Se encontró alta frecuencia de infecciones vaginales. Es necesario mejorar las definiciones y criterios de diagnóstico microbiológico de las co-infecciones y microbiota intermedia, para ser diagnosticadas en la práctica clínica. Se recomienda emplear cuestionarios más descriptivos para mejorar la utilidad del examen clínico.