Dysfunctional host cellular immune responses are associated with mortality in melioidosis.

Melioidosis is a tropical infection caused by the intracellular pathogen , an underreported and emerging global threat. As melioidosis-associated mortality is frequently high despite antibiotics, novel management strategies are critically needed. Therefore, we sought to determine whether functional changes in the host innate and adaptive immune responses are induced during acute melioidosis and are associated with outcome.

Phage-induced efflux down-regulation boosts antibiotic efficacy.

The interactions between a virus and its host vary in space and time and are affected by the presence of molecules that alter the physiology of either the host or the virus. Determining the molecular mechanisms at the basis of these interactions is paramount for predicting the fate of bacterial and phage populations and for designing rational phage-antibiotic therapies. We study the interactions between stationary phase Burkholderia thailandensis and the phage ΦBp-AMP1.

Induced prophages detected from the hemoculture: a biomarker for infection.

Bacteriophages (phages), viruses that infect bacteria, are found in abundance not only in the environment but also in the human body. The use of phages for the diagnosis of melioidosis, a tropical infectious disease caused by , is emerging as a promising novel approach, but our understanding of conditions under which prophages can be induced remains limited. Here, we first demonstrated the isolation of phages from the hemocultures of melioidosis patients.

Corrigendum: Pathogen genomics and phage-based solutions for accurately identifying and controlling pathogens.

[This corrects the article DOI: 10.3389/fmicb.2023.

Pathogen genomics and phage-based solutions for accurately identifying and controlling pathogens.

is a food-borne pathogen often linked to poultry sources, causing gastrointestinal infections in humans, with the numbers of multidrug resistant (MDR) isolates increasing globally. To gain insight into the genomic diversity of common serovars and their potential contribution to disease, we characterized antimicrobial resistance genes, and virulence factors encoded in 88 UK and 55 Thai isolates from poultry; the presence of virulence genes was detected through an extensive virulence determinants database compiled in this study. Long-read sequencing of three MDR isolates, each from a different serovar, was used to explore the links between virulence and resistance.

Activity of a Bacteriophage Cocktail to Control Growth in Avian, Porcine, and Human Epithelial Cell Cultures.

We examined the activity of phages to control the growth of chicken and swine strains in avian (CHIC-8E11), porcine (IPEC-1), and human (HT-29) cell cultures. We optimized a six-phage cocktail by selecting the five most effective myoviruses and a siphovirus that have optimal lysis on prevalent serovars. We observed ∼20% of 7 log PFU/well phage and 3-6 log CFU bacterial adhesions, and 3-5 log CFU bacterial invasion per 2 cm of the cultured cells at 2 h post-treatment.

Analysis of the role of the QseBC two-component sensory system in epinephrine-induced motility and intracellular replication of Burkholderia pseudomallei.

Burkholderia pseudomallei is a facultative intracellular bacterial pathogen that causes melioidosis, a severe invasive disease of humans. We previously reported that the stress-related catecholamine hormone epinephrine enhances motility of B. pseudomallei, transcription of flagellar genes and the production of flagellin.

A novel virulent Litunavirus phage possesses therapeutic value against multidrug resistant Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a notable nosocomial pathogen that can cause severe infections in humans and animals. The emergence of multidrug resistant (MDR) P. aeruginosa has motivated the development of phages to treat the infections.

Therapeutic effects of oral administration of lytic phages in a mouse model of non-typhoidal salmonellosis.

Acute non-typhoidal salmonellosis (NTS) caused by a Gram-negative bacterium serovar Typhimurium ( Tm) is one of the most common bacterial foodborne diseases worldwide. Bacteriophages (phages) can specifically target and lyse their host bacteria, including the multidrug-resistant strains, without collateral damage to other bacteria in the community. However, the therapeutic use of phages is still poorly investigated.

Lymphostatin, a virulence factor of attaching and effacing , inhibits proliferation and cytokine responses of human T cells in a manner associated with cell cycle arrest but not apoptosis or necrosis.

Lymphostatin is a virulence factor of enteropathogenic (EPEC) and non-O157 serogroup enterohaemorrhagic . Previous studies using whole-cell lysates of EPEC showed that lymphostatin inhibits the mitogen-activated proliferation of bulk human peripheral blood mononuclear cells (PBMCs) and the production of cytokines IL-2, IL-4, IL-5, and IFN-γ. Here, we used highly purified lymphostatin and PBMC-derived T cells to show that lymphostatin inhibits anti-CD3/anti-CD28-activated proliferation of human CD4 and CD8 T cells and blocks the synthesis of IL-2, IL-4, IL-10 and IFN-γ without affecting cell viability and in a manner dependent on an N-terminal DTD glycosyltransferase motif.

An Optimized Bacteriophage Cocktail Can Effectively Control and in .

spp. is a leading cause of gastrointestinal enteritis in humans where it is largely contracted via contaminated poultry and pork. Phages can be used to control infection in the animals, which could break the cycle of infection before the products are accessible for consumption.

Functional redundancy of Burkholderia pseudomallei phospholipase C enzymes and their role in virulence.

Phospholipase C (PLC) enzymes are key virulence factors in several pathogenic bacteria. Burkholderia pseudomallei, the causative agent of melioidosis, possesses at least three plc genes (plc1, plc2 and plc3). We found that in culture medium plc1 gene expression increased with increasing pH, whilst expression of the plc3 gene was pH (4.

Development of a broad-spectrum Salmonella phage cocktail containing Viunalike and Jerseylike viruses isolated from Thailand.

Salmonella is one of the most common agents of foodborne disease worldwide. As natural alternatives to traditional antimicrobial agents, bacteriophages (phages) are emerging as highly effective biocontrol agents against Salmonella and other foodborne bacteria. Due to the high diversity within the Salmonella genus and emergence of drug resistant strains, improved efforts are necessary to find broad range and strictly lytic Salmonella phages for use in food biocontrol.

Targeting Hidden Pathogens: Cell-Penetrating Enzybiotics Eradicate Intracellular Drug-Resistant Staphylococcus aureus.

is a major concern in human health care, mostly due to the increasing prevalence of antibiotic resistance. Intracellular localization of plays a key role in recurrent infections by protecting the pathogens from antibiotics and immune responses. Peptidoglycan hydrolases (PGHs) are highly specific bactericidal enzymes active against both drug-sensitive and -resistant bacteria.

Identification of Genes Induced During Infection of Macrophages by Differential Fluorescence Induction.

, the causative agent of melioidosis, can survive and replicate in macrophages. Little is known about genes that are induced during macrophage infection. We constructed a K96243 promoter trap library with genomic DNA fragments fused to the 5' end of a plasmid-borne gene encoding enhanced green fluorescent protein (eGFP).

Transketolase and vitamin B1 influence on ROS-dependent neutrophil extracellular traps (NETs) formation.

Neutrophil extracellular traps (NETs) are a recently identified, web-like, extracellular structure composed of decondensed nuclear DNA and associated antimicrobial granules. NETs are extruded into the extracellular environment via the reactive oxygen species (ROS)-dependent cell death pathway participating in inflammation and autoimmune diseases. Transketolase (TKT) is a thiamine pyrophosphate (vitamin B1)-dependent enzyme that links the pentose phosphate pathway with the glycolytic pathway by feeding excess sugar phosphates into the main carbohydrate metabolic pathways to generate biosynthetic reducing capacity in the form of NADPH as a substrate for ROS generation.

Quantitative Proteomics Reveals Differences in the Response of Neutrophils Isolated from Healthy or Diabetic Subjects to Infection with Capsule-Variant Burkholderia thailandensis.

In Thailand, diabetes mellitus is the most significant risk factor for melioidosis, a severe disease caused by Burkholderia pseudomallei. In this study, neutrophils isolated from healthy or diabetic subjects were infected with B. thailandensis E555, a variant strain with a B.

Characterization of Flagellotropic, Chi-Like Phages Isolated from Thai Poultry Farms.

Despite a wealth of knowledge on phages worldwide, little is known about poultry-associated phages from Thailand. Here, we isolated 108 phages from Thai poultry farms that infect serovar Typhimurium. Phages STm101 and STm118 were identified as temperate phages.

BimC Is Required for Actin-Based Motility, Intracellular Survival, and Virulence.

The intracellular pathogen , the etiological agent of melioidosis in humans and various animals, is capable of survival and movement within the cytoplasm of host cells by a process known as actin-based motility. The bacterial factor BimA is required for actin-based motility through its direct interaction with actin, and by mediating actin polymerization at a single pole of the bacterium to promote movement both within and between cells. However, little is known about the other bacterial proteins required for this process.

Inactivation of bpsl1039-1040 ATP-binding cassette transporter reduces intracellular survival in macrophages, biofilm formation and virulence in the murine model of Burkholderia pseudomallei infection.

Burkholderia pseudomallei, a gram-negative intracellular bacillus, is the causative agent of a tropical infectious disease called melioidosis. Bacterial ATP-binding cassette (ABC) transporters import and export a variety of molecules across bacterial cell membranes. At present, their significance in B.

Melioidosis in Thailand: Present and Future.

A recent modelling study estimated that there are 2800 deaths due to melioidosis in Thailand yearly. The Thailand Melioidosis Network (formed in 2012) has been working closely with the Ministry of Public Health (MoPH) to investigate and reduce the burden of this disease. Based on updated data, the incidence of melioidosis is still high in Northeast Thailand.

Evades Nramp1 (Slc11a1)- and NADPH Oxidase-Mediated Killing in Macrophages and Exhibits Nramp1-Dependent Virulence Gene Expression.

Bacterial survival in macrophages can be affected by the natural resistance-associated macrophage protein 1 (Nramp1; also known as solute carrier family 11 member a1 or Slc11a1) which localizes to phagosome membranes and transports divalent cations, including iron. Little is known about the role of Nramp1 in infection, in particular whether this differs for pathogenic species like causing melioidosis or non-pathogenic species like . Here we show that transfected macrophages stably expressing wild-type Nramp1 (Nramp1) control the net replication of , but not .

Identification of Candidate Host Cell Factors Required for Actin-Based Motility of Burkholderia pseudomallei.

Intracellular actin-based motility of the melioidosis pathogen Burkholderia pseudomallei requires the bacterial factor BimA. Located at one pole of the bacterium, BimA recruits and polymerizes cellular actin to promote bacterial motility within and between cells. Here, we describe an affinity approach coupled with mass spectrometry to identify cellular proteins recruited to BimA-expressing bacteria under conditions that promote actin polymerization.