Mechanisms of survival of trimethoprim-sulfamethoxazole-induced thymineless death.

Trimethoprim-sulfamethoxazole (SXT) is commonly used to treat diverse infections, including those associated with cystic fibrosis (CF) pulmonary disease. Studies with found that SXT impairs tetrahydrofolate production, leading to DNA damage, stress response induction, and accumulation of reactive oxygen species (ROS) in a process known as thymineless death (TLD). TLD survival can occur through the uptake of exogenous thymidine, countering the effects of SXT; however, a growing body of research has implicated central metabolism as another potentially important determinant of bacterial survival of SXT and other antibiotics.

Analysis of genetic requirements and nutrient availability for growth in cystic fibrosis sputum.

is one of the most common pathogens isolated from the lungs of people with cystic fibrosis (CF), but little is known about its ability to colonize this niche. We performed a Tn-seq screen to identify genes necessary for growth in media prepared from CF sputum. We identified 19 genes that were required for growth in all sputum media tested and dozens more that were required for growth in at least one sputum medium.

Combined inhibition of EZH2 and CDK4/6 perturbs endoplasmic reticulum-mitochondrial homeostasis and increases antitumor activity against glioblastoma.

He, we show that combined use of the EZH2 inhibitor GSK126 and the CDK4/6 inhibitor abemaciclib synergistically enhances antitumoral effects in preclinical GBM models. Dual blockade led to HIF1α upregulation and CalR translocation, accompanied by massive impairment of mitochondrial function. Basal oxygen consumption rate, ATP synthesis, and maximal mitochondrial respiration decreased, confirming disrupted endoplasmic reticulum-mitochondrial homeostasis.

Clinical and in vitro models identify distinct adaptations enhancing Staphylococcus aureus pathogenesis in human macrophages.

Staphylococcus aureus is a facultative intracellular pathogen of human macrophages, which facilitates chronic infection. The genotypes, pathways, and mutations influencing that phenotype remain incompletely explored. Here, we used two distinct strategies to ascertain S.

Selection Identifies Staphylococcus aureus Genes Influencing Biofilm Formation.

Staphylococcus aureus generates biofilms during many chronic human infections, which contributes to its growth and persistence in the host. Multiple genes and pathways necessary for S. aureus biofilm production have been identified, but knowledge is incomplete, and little is known about spontaneous mutations that increase biofilm formation as infection progresses.

Thymidine starvation promotes c-di-AMP-dependent inflammation during pathogenic bacterial infection.

Antimicrobials can impact bacterial physiology and host immunity with negative treatment outcomes. Extensive exposure to antifolate antibiotics promotes thymidine-dependent Staphylococcus aureus small colony variants (TD-SCVs), commonly associated with worse clinical outcomes. We show that antibiotic-mediated disruption of thymidine synthesis promotes elevated levels of the bacterial second messenger cyclic di-AMP (c-di-AMP), consequently inducing host STING activation and inflammation.

Impairment in inflammasome signaling by the chronic Pseudomonas aeruginosa isolates from cystic fibrosis patients results in an increase in inflammatory response.

Pseudomonas aeruginosa is a common respiratory pathogen in cystic fibrosis (CF) patients which undergoes adaptations during chronic infection towards reduced virulence, which can facilitate bacterial evasion of killing by host cells. However, inflammatory cytokines are often found to be elevated in CF patients, and it is unknown how chronic P. aeruginosa infection can be paradoxically associated with both diminished virulence in vitro and increased inflammation and disease progression.

Polyclonality, Shared Strains, and Convergent Evolution in Chronic Cystic Fibrosis Airway Infection.

is the most common respiratory pathogen isolated from patients with cystic fibrosis (CF) in the United States. Although modes of acquisition and genetic adaptation have been described for , resulting in improved diagnosis and treatment, these features remain more poorly defined for . To characterize the molecular epidemiology and genetic adaptation of during chronic CF airway infection and in response to antibiotic therapy.

Repeated isolation of an antibiotic-dependent and temperature-sensitive mutant of Pseudomonas aeruginosa from a cystic fibrosis patient.

Background: Bacteria adapt to survive and grow in different environments. Genetic mutations that promote bacterial survival under harsh conditions can also restrict growth. The causes and consequences of these adaptations have important implications for diagnosis, pathogenesis, and therapy.

Maintenance tobramycin primarily affects untargeted bacteria in the CF sputum microbiome.

Rationale: The most common antibiotic used to treat people with cystic fibrosis (PWCF) is inhaled tobramycin, administered as maintenance therapy for chronic lung infections. While the effects of inhaled tobramycin on abundance and lung function diminish with continued therapy, this maintenance treatment is known to improve long-term outcomes, underscoring how little is known about why antibiotics work in CF infections, what their effects are on complex CF sputum microbiomes and how to improve these treatments.

Objectives: To rigorously define the effect of maintenance tobramycin on CF sputum microbiome characteristics.

Elevated exopolysaccharide levels in Pseudomonas aeruginosa flagellar mutants have implications for biofilm growth and chronic infections.

Pseudomonas aeruginosa colonizes the airways of cystic fibrosis (CF) patients, causing infections that can last for decades. During the course of these infections, P. aeruginosa undergoes a number of genetic adaptations.

Prevalence and clinical associations of Staphylococcus aureus small-colony variant respiratory infection in children with cystic fibrosis (SCVSA): a multicentre, observational study.

Background: Staphylococcus aureus is the bacterium cultured most often from respiratory secretions of people with cystic fibrosis. Both meticillin-susceptible S aureus and meticillin-resistant S aureus (MRSA) can adapt to form slow-growing, antibiotic-resistant isolates known as small-colony variants that are not routinely identified by clinical laboratories. We aimed to determine the prevalence and clinical significance of S aureus small-colony variants and their subtypes among children with cystic fibrosis.

Human and Extracellular DNA Depletion for Metagenomic Analysis of Complex Clinical Infection Samples Yields Optimized Viable Microbiome Profiles.

Metagenomic sequencing is a promising approach for identifying and characterizing organisms and their functional characteristics in complex, polymicrobial infections, such as airway infections in people with cystic fibrosis. These analyses are often hampered, however, by overwhelming quantities of human DNA, yielding only a small proportion of microbial reads for analysis. In addition, many abundant microbes in respiratory samples can produce large quantities of extracellular bacterial DNA originating either from biofilms or dead cells.

Restoring Cystic Fibrosis Transmembrane Conductance Regulator Function Reduces Airway Bacteria and Inflammation in People with Cystic Fibrosis and Chronic Lung Infections.

Rationale: Previous work indicates that ivacaftor improves cystic fibrosis transmembrane conductance regulator (CFTR) activity and lung function in people with cystic fibrosis and G551D-CFTR mutations but does not reduce density of bacteria or markers of inflammation in the airway. These findings raise the possibility that infection and inflammation may progress independently of CFTR activity once cystic fibrosis lung disease is established.

Objectives: To better understand the relationship between CFTR activity, airway microbiology and inflammation, and lung function in subjects with cystic fibrosis and chronic airway infections.

Silicon-dioxide-polyvinylpyrrolidone as a wound dressing for skin defects in a murine model.

Objective: There is a high demand for temporary wound dressings that improve wound healing and regeneration. Silicon (as SiO) has been shown to support the growth and collagen formation in biological systems.

Methods: A nanocomposite was made from PVP (polyvinylpyrrolidon), nano-sized silica aggregates and water and served for fabrication of a wet dressing material (SiO-PVP gel, by cross-linking the gel) and a freeze-dried dressing material (SiO-PVP fleece).

LasR Variant Cystic Fibrosis Isolates Reveal an Adaptable Quorum-Sensing Hierarchy in Pseudomonas aeruginosa.

Unlabelled: Chronic Pseudomonas aeruginosa infections cause significant morbidity in patients with cystic fibrosis (CF). Over years to decades, P. aeruginosa adapts genetically as it establishes chronic lung infections.

Staphylococcus aureus Protein A Mediates Interspecies Interactions at the Cell Surface of Pseudomonas aeruginosa.

Unlabelled: While considerable research has focused on the properties of individual bacteria, relatively little is known about how microbial interspecies interactions alter bacterial behaviors and pathogenesis. Staphylococcus aureus frequently coinfects with other pathogens in a range of different infectious diseases. For example, coinfection by S.

Optimized In Vitro Antibiotic Susceptibility Testing Method for Small-Colony Variant Staphylococcus aureus.

Staphylococcus aureus small-colony variants (SCVs) emerge frequently during chronic infections and are often associated with worse disease outcomes. There are no standardized methods for SCV antibiotic susceptibility testing (AST) due to poor growth and reversion to normal-colony (NC) phenotypes on standard media. We sought to identify reproducible methods for AST of S.

Strength in diversity.

In this issue of Cell Host & Microbe, Hammer et al. (2014) show that distinct, slow-growing bacteria have better in vitro and in vivo growth and virulence when cocultured than in isolation. They provide evidence that the observed inter- and intraspecies "complementation" involves the intercellular exchange of metabolites.

The interrelation between victimization and bullying inside young offender institutions.

Bullying and victimization are serious problems within prisons. Young Offender Institutions (YOIs), in particular, suffer from high rates of inmate-on-inmate violence. More recent theories about the development of bullying in closed custody institutions imply a relationship between the experience of victimization and the usage of bullying.

Pseudomonas aeruginosa in vitro phenotypes distinguish cystic fibrosis infection stages and outcomes.

Rationale: Pseudomonas aeruginosa undergoes phenotypic changes during cystic fibrosis (CF) lung infection. Although mucoidy is traditionally associated with transition to chronic infection, we hypothesized that additional in vitro phenotypes correlate with this transition and contribute to disease.

Objectives: To characterize the relationships between in vitro P.

Pseudomonas aeruginosa phenotypes associated with eradication failure in children with cystic fibrosis.

Background: Pseudomonas aeruginosa is a key respiratory pathogen in people with cystic fibrosis (CF). Due to its association with lung disease progression, initial detection of P. aeruginosa in CF respiratory cultures usually results in antibiotic treatment with the goal of eradication.

Pediatric infection and intestinal carriage due to extended-spectrum-cephalosporin-resistant Enterobacteriaceae.

The objective of this study is to describe the epidemiology of intestinal carriage with extended-spectrum-cephalosporin-resistant Enterobacteriaceae in children with index infections with these organisms. Patients with resistant Escherichia coli or Klebsiella bacteria isolated from the urine or a normally sterile site between January 2006 and December 2010 were included in this study. Available infection and stool isolates underwent phenotypic and molecular characterization.

Staphylococcus aureus small-colony variants are independently associated with worse lung disease in children with cystic fibrosis.

Background: Cystic fibrosis (CF) lung disease is associated with diverse bacteria chronically infecting the airways. Slow-growing, antibiotic-resistant mutants of Staphylococcus aureus known as small-colony variants (SCVs) have been isolated from respiratory secretions from European adults and children with CF lung disease using specific but infrequently used culture techniques. Staphylococcus aureus SCVs can be selected either by exposure to specific antibiotics or by growth with another CF pathogen, Pseudomonas aeruginosa.