Investigação de genes de virulência associados ao processo invasivo de diferentes cepas de Shigella spp. de origem clínica

Abstract

Enterobacteria are the main cause of dysentery worldwide. From this family, Shigella is noteworthy for being the causative agent of shigellosis, an enteric disease that annually affects about 165 million people, leading to death over one million, with children under five years of age being the main affected age group. Its transmission occurs through the fecal-oral route through ingestion of contaminated food or water, or contact between people, being more effective in places where basic sanitation is precarious or non-existent. These bacteria have the potential to escape the immune system, invading and destroying the cells that line the large intestine, where they cause ulcerations in the mucosa and diarrhea with blood and mucus. In addition to diarrhea, the infection triggers symptoms such as fever, abdominal cramps, and rectal pain, usually the uncomplicated recovery of these patients occurs within seven days. From 2007 to 2009, the research group of the Laboratory for Diagnosis and Control of Infectious Diseases in the Amazon carried out an epidemiological study evaluating the pathogens that cause diarrhea in children treated in public hospitals in Manaus - AM. Among the isolated pathogens, Shigella was identified as the fifth major causative agent of diarrhea among the cases found. Molecular studies performed with this pathogen identified variations between the isolated strains in the presence of key virulence genes for the activation of the invasion and subsequent clinical manifestation. As all strains of Shigella were isolated from cases of diarrhea, we asked ourselves about the relationship of these genes with in vitro invasion. Given the above, we characterized genus, species and virulence genes of Shigella with the use of Polymerase Chain Reaction (PCR), we identified the antibiotic resistance profile, we also analyzed the invasiveness of these different strains of clinical origin, by means of in vitro tests in phagocytic and non-phagocytic cells, in a qualitative and quantitative way. The results evidenced a strong association with the presence of virulence genes and cell invasion of Shigella strains of clinical origin. Keywords: Shigella; virulence genes; Cell Invasion; Dysentery