Host restriction, pathogenesis and chronic carriage of typhoidal Salmonella

Transcriptional profiling links unique human macrophage phenotypes to the growth of intracellular Salmonella enterica serovar Typhi

Macrophages provide a crucial environment for Salmonella enterica serovar Typhi (S. Typhi) to multiply during typhoid fever, yet our understanding of how human macrophages and S. Typhi interact remains limited. In this study, we delve into the dynamics of S. Typhi replication within human macrophages and the resulting heterogeneous transcriptomic responses of macrophages during infection. Our study reveals key factors that influence macrophage diversity, uncovering distinct immune and metabolic pathways associated with different stages of S. Typhi intracellular replication in macrophages. Of note, we found that macrophages harboring replicating S. Typhi are skewed towards an M1 pro-inflammatory state, whereas macrophages containing non-replicating S. Typhi exhibit neither a distinct M1 pro-inflammatory nor M2 anti-inflammatory state. Additionally, macrophages with replicating S. Typhi were characterized by the increased expression of genes associated with STAT3 phosphorylation and the activation of the STAT3 transcription factor. Our results shed light on transcriptomic pathways involved in the susceptibility of human macrophages to intracellular S. Typhi replication, thereby providing crucial insight into host phenotypes that restrict and support S. Typhi infection.

Persistent Salmonella infections in humans are associated with mutations in the BarA/SirA regulatory pathway

Several bacterial pathogens, including Salmonella enterica, can cause persistent infections in humans by mechanisms that are poorly understood. By comparing genomes of isolates longitudinally collected from 256 prolonged salmonellosis patients, we identified repeated mutations in global regulators, including the barA/sirA two-component regulatory system, across multiple patients and Salmonella serovars. Comparative RNA-seq analysis revealed that distinct mutations in barA/sirA led to diminished expression of Salmonella pathogenicity islands 1 and 4 genes, which are required for Salmonella invasion and enteritis. Moreover, barA/sirA mutants were attenuated in an acute salmonellosis mouse model and induced weaker transcription of host immune responses. In contrast, in a persistent infection mouse model, these mutants exhibited long-term colonization and prolonged shedding. Taken together, these findings suggest that selection of mutations in global virulence regulators facilitates persistent Salmonella infection in humans, by attenuating Salmonella virulence and inducing a weaker host inflammatory response.

Determination of the Salmonella intracellular lifestyle by the diversified interaction of Type III secretion system effectors and host GTPases

Intracellular bacteria have developed sophisticated strategies to subvert the host endomembrane system to establish a stable replication niche. Small GTPases are critical players in regulating each step of membrane trafficking events, such as vesicle biogenesis, cargo transport, tethering, and fusion events. Salmonella is a widely studied facultative intracellular bacteria. Salmonella delivers several virulence proteins, termed effectors, to regulate GTPase dynamics and subvert host trafficking for their benefit. In this review, we summarize an updated and systematic understanding of the interactions between bacterial effectors and host GTPases in determining the intracellular lifestyle of Salmonella. This article is categorized under: Infectious Diseases > Molecular and Cellular Physiology.

Hematology Parameter Based on Tubex TF® Color Scale Result in Typhoid Fever Patients

BACKGROUND: Infection with Salmonella enterica subspecies serovar Typhi and Paratyphi A, B, and C causes typhoid and paratyphoid fever. This is a major source of mortality and morbidity, especially in youngsters. Typhoid fever frequently causes non-specific symptoms. Symptoms that appear obstructively are comparable to those seen in other infectious illnesses and have similar clinical manifestations. Complications can be avoided with early detection and treatment. AIM: This study will look at the hematology parameter profile to determine whether there are any hematological differences between patients with high and low antibodies. METHODS: The research was conducted in Bengkulu, Indonesia, in June 2020 until July 2021. Subject collection was done according to inclusion and exclusion criteria. Subjects have given informed consent. The research included a total of 39 subject patients. Demographic data were collected using a questionnaire and 3 mL of blood was taken. Blood was examined for Tubex TF® and hematological examination. Statistical analysis used independent t-test and performed with SPSS. RESULTS: The research included a total of 39 subject patients. Most were male and most were aged 21–25 years. The most common symptom felt by the subject was gastrointestinal complaints. The analysis was carried out based on the color scale value of the Tubex TF® which was divided into two groups, 4 color scale groups and 6 color scale groups. Hematological parameters of hemoglobin, hematocrit, WBC, platelets, monocytes, lymphocytes, and neutrophils showed no significant difference. However, color scale group 6 showed lower value than 4 color scale group. CONCLUSION: Hematological indicators in typhoid fever were not substantially changed in Tubex TF®-positive typhoid fever patients. Clinicians can offer the same therapy in instances with typhoid fever, despite having differing positive Tubex TF® scores.

Through the Looking Glass: Genome, Phenome, and Interactome of Salmonella enterica

This review revisits previous concepts on biological phenomenon contributing to the success of the Salmonella enterica subspecies I as a pathogen and expands upon them to include progress in epidemiology based on whole genome sequencing (WGS). Discussion goes beyond epidemiological uses of WGS to consider how phenotype, which is the biological character of an organism, can be correlated with its genotype to develop a knowledge of the interactome. Deciphering genome interactions with proteins, the impact of metabolic flux, epigenetic modifications, and other complex biochemical processes will lead to new therapeutics, control measures, environmental remediations, and improved design of vaccines.