Infecção por Shigella/escherichia coli enteroinvasiva, genes de virulência e copatógenos em crianças de estudo caso-controle no semiárido brasileiro

Abstract

Shigella and Escherichia coli Enteroinvasive (EIEC) constitute the pathotype Shigella/EIEC that cause Shigellosis. This infection is an important world public health problem, mainly in the children in development countries, because its clinic severity, lack of vaccine and high rate of antimicrobial resistance. This study aimed to develop primers for virulence-related genes and to evaluate clinical symptoms of Shigella/EIEC intestinal infection of children from case-control study on brazilian Semiarid. It was carried out a case-control study in six different cities of semiarid with 1200 children with 2 to 36 age months, distributed in the case group, when they had diarrheal episodes in the last 24 hours, and in the control group, when they had not diarrheal episodes. Fecal samples of each children were colected and its DNA was extracted for pathogens diagnosis by Luminex Bio-Plex® 200 (Bio-Rad, Califórnia, EUA), which 148 (12.33%) samples were obtained with positive DNA for Shigella/EIEC. From these 148 samples, fecal DNA was reextracted and the diagnosis was made by conventional PCR. The positive DNA for the pathotype was used for the detection of virulence genes. The clinic, demografics and socioeconomics dates were obtained by questionnaire answered by children parents or responsables. The dates of co-infectants enteropathogens with this pathotype were obtained from Luminex detections results. It was detected the pathotype in 7% (42/600) of case group children and in 3% (18/600) of control group, with association of pathotype detection and presence of diarrhea (p = 0.0021, OR = 2.43, IC95% 1.384 to 4.279). It was observed that 91.6% (55/60) of these pathotype positive samples had co-infections with least one other enteropathogen. There was association of co-infection with Salmonella spp. with abdominal pain presence (p = 0.0262; OR = 5.75; IC95% = 1.362 to 20.73). It was analyzed 28 virulence gens, of which the most prevalent is iucB gen (90%, 54/60). Some of these gens was associated with diarrhea cases: the gene sen (p = 0.0267; OR = 4.25; IC95% = 1.27 to 14.15), which encodes the ShET1 enterotoxin; genes ipgB2 (p = 0.0267; OR = 4.25; IC95% = 1.27 to 14.15) and ipgB1 (p= 0.0354; OR = 3.66; IC95% = 1.12 to 11,9), which encodes the ruffling of membrane of host cells; and the gene ospF (p= 0,0354; OR = 3,66; IC95% = 1,12-11,9), which encodes the suppression of host immune response. About clinical manifestations addicted to diarrhea, it was observed that the infected and symptomatic children had mild symptoms. The results demonstrated high frequence of Shigella/EIEC co-infections with least one other enteropathogen. The infection with Salmonella spp was associated with abdominal pain (p = 0.0262; OR = 5.75; 95% CI = 1.36 to 20.73. The results showed the association of diarrhea presence on these children with pathotype detection. The evaluation of presence of sen, ipgB1, ipgB2 e ospF genes suggest the association of factors enconding by these genes with impact in diarrhea. Further, the presence of factor related with pathotype intra and intercellular spreading was associated with fever in children. In addition, it was observed high frequence of pathotype copathogens and abdominal pain presence associated with presence of co-infection with Salmonella spp.