| Congresso Brasileiro de Microbiologia 2023 | Resumo: 175-1 | ||||
Resumo:Campylobacter jejuni is a main causative agent of human diarrheal diseases in many countries. Specifically, in Brazil C. jejuni has been underdiagnosed and understudied. Therefore, studies that characterize strains of this species isolated in this country are of great importance. The aims of this study were to assess the survival of C. jejuni isolates from different sources in Brazil under different stress conditions, the invasion and survival in human epithelial cells (Caco-2) and macrophages (U937) and the frequency of virulence genes. A total of 46 C. jejuni strains isolated from humans (18), animals (14) and food (14) between 1996 and 2016 in four states of Brazil were analyzed. For the survivability in 7.5% of NaCl, the pellets were resuspended in 1 mL of BHI (control) and BHI supplemented with 7.5% of NaCl (stress). Control and stress aliquots were taken after 10 min, 1 hour and 2 hours. For the tolerance to temperature variations, the pellets were resuspended in 1 mL of BHI incubated at 4ºC and 37ºC (stress) and 42ºC (control). Control and stress aliquots were taken after 30 min and 24 hours. Three experiments were conducted on different days. The invasiveness in Caco-2 cells was accessed after 90 minutes of bacteria-cell interaction. The survival in U937 human macrophages was accessed after 30 minutes of bacteria-cell interaction. In both assays, the multiplicity of infection employed was 100:1. Strain C. jejuni ATCC 33291 was included in the assays for comparison purposes. Virulence genes were screened in silico through whole genome sequencing data of the strains using the VF Analyzer. All strains studied survived under incubation in BHI supplemented with 7.5% NaCl after 10 minutes, 1 hour and 2 hours with survival rates ranging from 3 to 100%. All strains studied showed growth in the temperatures analyzed after 30 minutes and 24 hours, with a survival rate of 5 to 100% at 4ºC and 50 to 100% at 37ºC. A total of 43 (93.5%) C. jejuni strains studied invaded Caco-2 epithelial cells at levels greater than the C. jejuni ATCC 33291. In addition, 36 (78.3%) C. jejuni strains studied survived in U937 human macrophages at levels greater than the C. jejuni ATCC 33291. Regarding the virulence genes, the 46 C. jejuni strains showed 162 genes related to colonization, adhesion, motility, invasion, toxin production, chemotaxis and type 6 secretion system. In conclusion, the presence of important virulence genes, the high survival rates under stress conditions and high invasion and survival rates in human cells analyzed highlighted the pathogenic potential of the C. jejuni strains from Brazil and suggest that more rigorous control measures may be needed, given the hazard of contaminated food with this pathogen.
Financial support: FAPESP Palavras-chave: Campylobacter jejuni, Whole Genome Sequence, stress survival, virulome, host cells invasion and survival Agência de fomento:FAPESP- Fundação de Amparo a Pesquisa do Estado de São Paulo | |||||