Whole-genome sequencing reveals a link between ß-lactam resistance and synthetases of the alarmone (p)ppGpp in Staphylococcus aureus.

The overwhelming majority of methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates exhibit a peculiar heterogeneous resistance to ß-lactam antibiotics: in cultures of such strains, the majority of cells display only a low level of methicillin resistance--often close to the MIC breakpoint of susceptible strains. Yet, in the same cultures, subpopulations of bacteria exhibiting very high levels of resistance are also present with variable frequencies, which are characteristic of the particular MRSA lineage. The mechanism of heterogeneous resistance is not understood. We describe here an experimental system for exploring the mechanism of heterogeneous resistance. Copies of the resistance gene mecA cloned into a temperature-sensitive plasmid were introduced into the fully sequenced methicillin-susceptible clinical isolate S. aureus strain 476. Transductants of strain 476 expressed methicillin resistance in a heterogeneous fashion: the great majority of cells showed only low MIC (0.75 µg/ml) for the antibiotic, but a minority population of highly resistant bacteria (MIC >300 µg/ml) was also present with a frequency of ∼10(-4). The genetic backgrounds of the majority and minority cells were compared by whole-genome sequencing: the only differences detectable were two point mutations in relA of the highly resistant minority population of bacteria. The relA gene codes for the synthesis of (p)ppGpp, an effector of the stringent stress response. Titration of (p)ppGpp showed increased amounts of this effector in the highly resistant cells. Involvement of (p)ppGpp synthesis genes may explain some of the perplexing aspects of ß-lactam resistance in MRSA, since many environmental and genetic changes can modulate cellular levels of (p)ppGpp.

Características psicosociales y familiares relacionadas con intento de suicidio en una población adolescente en Bogotá–2009 / Características psicossociais e familiares relacionadas à tentativa de suicídio em uma população adolescente em Bogotá (2009) / Psycho-social and family characteristics related to attempted suicide in an adolescent population in Bogota–2009

Las conductas suicidas se han constituido en una causa importante de morbi-mortalidad mundial. En el 2006, el suicidio pasó al tercer lugar como principal causa de muerte en personas de 15 a 44 años. Se han identificado factores de riesgo para esta conducta y signos de alarma específicos, sin embargo, los adolescentes presentan riesgos adicionales como imitación, identificación social e inestabilidad emocional.Se realizó un estudio transversal descriptivo en adolescentes entre los 10 y 17 años que consultaron por intento de suicidio al servicio de urgencias de dos hospitales en Bogotá, aplicando un instrumento de recolección de información diligenciado por los padres o acudientes de 14 casos, previa firma de consentimiento informado. El estudió mostró que la edad más prevalente fueron los 16 años, representando el 43%; el género fue el femenino, representando el 71,5%. Ninguno reportó diagnóstico de enfermedad mental previa, y solo en tres casos hubo reporte de consumo de sustancias.Ninguno de los casos reportó que los pacientes hubieran tenido comportamientos de búsqueda de ayuda previa.Debido al reducido número de casos sólo se pueden describir hallazgos reportados, en este momento no se pueden hacer afirmaciones con respecto a características familiares, para esto se requeriría aplicar el instrumento en un mayor número de pacientes.

Os comportamentos suicidas têm se tornado uma das principais causas de morbidade e mortalidade no mundo. Em 2006, o suicídio foi a terceira causa principal de morte em pessoas entre 15 e 44 anos. Para este comportamento identificaram-se fatores de risco e sinais de advertência. Existem otros riscos para os adolescentes: a imitação, a identificação social e a instabilidade emocional.Foi realizado um estudo transversal descritivo em adolescentes de 10 a 17 anos que consultaram o departamento de emergência de dois hospitais de Bogotá por tentativa de suicídio. Utilizou-se um instrumento de coleta de dados preenchidos pelos pais ou responsáveis dos adolescentes em 14 casos, após a assinatura de um consentimento informado. O estudo mostrou que a faixa etária prevalente é 16 anos (43%), o sexo foi o feminino (71,5%). Nenhum caso relata diagnóstico prévio de doença mental, e apenas três casos relataram o uso de substâncias.Nenhum dos casos informou que os pacientes tenham procurado ajuda previa.Devido ao pequeno número de casos, só podem descrever-se achados relatados. Neste momento, nós não podemos fazer afirmações sobre as características da família, já que seria necessária a aplicação do instrumento em um número maior de pacientes.

Suicidal behavior has become a major cause of morbidity and mortality worldwide. In 2006, it was the third leading cause of death among persons age 15 to 44. Risk factors for this behavior and specific warning signs have been identified. However, adolescents may be plagued by additional risk factors such as imitation, social identification, and emotional instability.The authors conducted a transversal- descriptive study with adolescents between 10 and 17 years of age who were admitted for attempted suicide to the emergency rooms of two hospitals in Bogota. The data was collected with an instrument filled out by the parents or guardians of 14 different patients, after having signed a letter giving informed consent. The study showed the most prevalent age was 16, accounting for 43% of the sample. The female population was the most prevalent in terms of gender, accounting for 71.5%. None of the patients reported a previous diagnosis of mental illness and, in only three specific cases, was there a report of substance abuse. None of the patients reported having sought help prior to attempting suicide.Due to the small number of cases in the sample, it is possible only to describe the reported findings. At this point, conclusions cannot be reached with respect to family characteristics. To do so would require applying the instrument to a larger sample of patients.

Unique features of a highly pathogenic Campylobacter jejuni strain.

Campylobacter jejuni, a major human enteric pathogen, exhibits significant strain-to-strain differences which result in differences in pathogenic potential. C. jejuni 81-176 is a highly virulent strain that exhibits unique pathogenic features and is used by many research laboratories. We have determined the nucleotide sequence of its genome and compared it to the genomes of other sequenced C. jejuni strains. We identified a number of unique genetic features which may confer specific metabolic and pathogenic properties on this strain. We have also identified regions of the C. jejuni genome that are hot spots for the integration of horizontally acquired genetic material. This information should help the understanding of the pathogenesis of C. jejuni and, in particular, the unique features of this highly pathogenic strain.