RESUMO
Many pathogens colonize different anatomical sites, but the selective pressures contributing to survival in the diverse niches are poorly understood. Group A Streptococcus (GAS) is a human-adapted bacterium that causes a range of infections. Much effort has been expended to dissect the molecular basis of invasive (sterile-site) infections, but little is known about the genomes of strains causing pharyngitis (streptococcal "sore throat"). Additionally, there is essentially nothing known about the genetic relationships between populations of invasive and pharyngitis strains. In particular, it is unclear if invasive strains represent a distinct genetic subpopulation of strains that cause pharyngitis. We compared the genomes of 86 serotype M3 GAS pharyngitis strains with those of 215 invasive M3 strains from the same geographical location. The pharyngitis and invasive groups were highly related to each other and had virtually identical phylogenetic structures, indicating they belong to the same genetic pool. Despite the overall high degree of genetic similarity, we discovered that strains from different host environments (i.e., throat, normally sterile sites) have distinct patterns of diversifying selection at the nucleotide level. In particular, the pattern of polymorphisms in the hyaluronic acid capsule synthesis operon was especially different between the two strain populations. This finding was mirrored by data obtained from full-genome analysis of strains sequentially cultured from nonhuman primates. Our results answer the long-standing question of the genetic relationship between GAS pharyngitis and invasive strains. The data provide previously undescribed information about the evolutionary history of pathogenic microbes that cause disease in different anatomical sites.
Assuntos
Evolução Molecular , Genoma Bacteriano/fisiologia , Faringite/genética , Filogenia , Infecções Estreptocócicas/genética , Streptococcus pyogenes/genética , Animais , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , PrimatasRESUMO
Group A Streptococcus (GAS) is a human-adapted pathogen that causes a variety of diseases, including pharyngitis and invasive infections. GAS strains are categorized by variation in the nucleotide sequence of the gene (emm) that encodes the M protein. To identify the emm types of GAS strains causing pharyngitis in Ontario, Canada, we sequenced the hypervariable region of the emm gene in 4,635 pharyngeal GAS isolates collected during 2002-2010. The most prevalent emm types varied little from year to year. In contrast, fine-scale geographic analysis identified inter-site variability in the most common emm types. Additionally, we observed fluctuations in yearly frequency of emm3 strains from pharyngitis patients that coincided with peaks of emm3 invasive infections. We also discovered a striking increase in frequency of emm89 strains among isolates from patients with pharyngitis and invasive disease. These findings about the epidemiology of GAS are potentially useful for vaccine research.
Assuntos
Antígenos de Bactérias/genética , Proteínas da Membrana Bacteriana Externa/genética , Proteínas de Transporte/genética , Faringite/epidemiologia , Faringite/microbiologia , Infecções Estreptocócicas/epidemiologia , Streptococcus pyogenes/classificação , Alelos , Criança , Pré-Escolar , Genótipo , Humanos , Lactente , Ontário/epidemiologia , Faringe/microbiologia , Filogeografia , Streptococcus pyogenes/genética , Streptococcus pyogenes/isolamento & purificaçãoRESUMO
Catastrophic antiphospholipid syndrome (CAPS) is an accelerated form of the antiphospholipid antibody syndrome resulting in multi-organ ischemia and failure. It is a rare and life-threatening condition that can be easily mistaken with hemolysis elevated liver enzymes low platelets syndrome, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome. In order to make a diagnosis, it is required to have multi-organ thrombosis over 1 week affecting at least three organs or systems, and to have positive antiphospholipid antibody on two occasions (6 weeks apart), and histopathologic confirmation of small vessel occlusion. However, due to similarities in clinical and laboratory findings between CAPS and some other obstetric complications, potential misdiagnosis or delay in diagnosis are common, increasing the risk of adverse maternal and perinatal outcomes. In this review we summarized information presented in previous studies, focusing on CAPS related to pregnancy. We reviewed diagnostic criteria, differential diagnosis, and common presentation ranging from malaise, abdominal pain, dyspnea, hypertension, to altered mental status and seizures. We also discussed management in pregnancy and included a detailed algorithm with steps to take. Of note, the most significant reduction in mortality was seen in patients receiving triple therapy which will be discussed in this review.