Project description:The rising prevalence of antimicrobial resistance in Salmonella enterica serovars Typhi and Paratyphi A, causative agents of typhoid and paratyphoid, have led to fears of untreatable infections. Of specific concern is the emerging resistance against azithromycin, the only remaining oral drug to treat extensively drug resistant (XDR) typhoid. Since the first report of azithromycin resistance from Bangladesh in 2019, cases have been reported from Nepal, India, and Pakistan. The genetic basis of this resistance is a single point mutation in the efflux pump AcrB (R717Q/L). Here, we report 38 additional cases of azithromycin-resistant (AzmR) Salmonella Typhi and Paratyphi A isolated in Bangladesh between 2016 and 2018. Using genomic analysis of 56 AzmR isolates from South Asia with AcrB-R717Q/L, we confirm that this mutation has spontaneously emerged in different Salmonella Typhi and Paratyphi A genotypes. The largest cluster of AzmR Typhi belonged to genotype 4.3.1.1; Bayesian analysis predicts the mutation to have emerged sometime in 2010. A travel-related Typhi isolate with AcrB-R717Q belonging to 4.3.1.1 was isolated in the United Kingdom, increasing fears of global spread. For real-time detection of AcrB-R717Q/L, we developed an extraction-free, rapid, and low-cost mismatch amplification mutation assay (MAMA). Validation of MAMA using 113 AzmR and non-AzmR isolates yielded >98% specificity and sensitivity versus phenotypic and whole-genome sequencing assays currently used for azithromycin resistance detection. With increasing azithromycin use, AcrB-R717Q/L is likely to be acquired by XDR strains. The proposed tool for active detection and surveillance of this mutation may detect pan-oral drug resistance early, giving us a window to intervene.IMPORTANCE In the early 1900s, with mortality of ∼30%, typhoid and paratyphoid ravaged parts of the world; with improved water, sanitation, and hygiene in resource-rich countries and the advent of antimicrobials, mortality dwindled to <1%. Today, the burden rests disproportionately on South Asia, where the primary means for combatting the disease is antimicrobials. However, prevalence of antimicrobial resistance is rising and, in 2016, an extensively drug resistant Typhi strain triggered an ongoing outbreak in Pakistan, leaving only one oral drug, azithromycin, to treat it. Since the description of emergence of azithromycin resistance, conferred by a point mutation in acrB (AcrB-R717Q/L) in 2019, there have been increasing numbers of reports. Using genomics and Bayesian analysis, we illustrate that this mutation emerged in approximately 2010 and has spontaneously arisen multiple times. Emergence of pan-oral drug resistant Salmonella Typhi is imminent. We developed a low-cost, rapid PCR tool to facilitate real-time detection and prevention policies.
Project description:Azithromycin has been shown to have anti-fibrotic effects on idiopathic lung fibroblasts (IPF). We thus wanted to investigate involved genes and pathways by microarray analysis. We treated normal human lung fibroblasts with Azithromycin (50uM) for 24h and compared them to non-treated samples.
Project description:Microarrays were used to evaluate the effects of azithromycin and an inflammatory stimulus (SMM) on human airway epithelium. Effects of azithromycin treatment were evaluated at 6, 24 and 48 hours. Effects of SMM were evaluated at 6 and 24 hours. In addition, pretreatment with azithromycin was used to evaluate the modulatory effects on SMM-induced inflammation. SMM=supernatant from microcorpulent material from human cystic fibrosis airways. Experiment Overall Design: 10 treatments total, 3-4 samples (patient codes = replicates) per treatment.
Project description:Microarrays were used to evaluate the effects of azithromycin and an inflammatory stimulus (SMM) on human airway epithelium. Effects of azithromycin treatment were evaluated at 6, 24 and 48 hours. Effects of SMM were evaluated at 6 and 24 hours. In addition, pretreatment with azithromycin was used to evaluate the modulatory effects on SMM-induced inflammation. SMM=supernatant from microcorpulent material from human cystic fibrosis airways. Keywords: timecourse, treatment comparisons.
Project description:Long-term, low dose azithromycin reduces exacerbation frequency in COPD yet the mechanism remains unclear. This study characterises changes to gene expression in patients with neutrophilic COPD in response to long term low dose azithromycin therapy. Patients with neutrophilic COPD (>61% or >162x10^4/mL sputum neutrophils) were randomised to 12 weeks of either azithromycin or placebo treatment. RNA was extracted from sputum and blood collected before (pre) and after (post) treatment.
Project description:Azithromycin binds to the nascent peptide exit tunnel (NPET) close to the peptidyltransferase center (PTC) of the ribosome, which obstructs the NPET and subsequently induces ribosome stalling and depletion of intracellular pools of tRNAs. To understand the mechanism through which azithromycin represses the transcription of mutation promoting genes, we utilized ribosome profiling to analyze azithromycin caused redistribution of ribosomes on the cellular mRNAs. Wild type PA14 was treated with 16 mg/L azithromycin for 3 hours.
Project description:The effects of azithromycin on whole blood gene expression using the nCounter XT human autoimmune profiling panel was assessed in 8 sarcoidosis patients before and after 1 month of azithromycin treatment.
Project description:Salmonella enterica represent a major disease burden worldwide. While non-typhoidal Salmonella (NTS) serovars trigger self-limiting diarrhoea, leading to occasional secondary bacteraemia, S. enterica serovar Typhi is responsible for potentially life-threatening Typhoid fever. Dendritic cells (DCs) are key professional antigen presenting cells of the human immune system. The ability of pathogenic bacteria to subvert DC functions and prevent T cell recognition contributes to their survival and dissemination within the host. Here, we adapted Dual RNA-sequencing to define how different Salmonella pathovariants remodel their gene expression in tandem with that of infected DCs. We find DCs harness iron handling pathways to defend against invading Salmonellas, which, the human pathogen S. Typhi is able to circumvent. We show that S. Typhi mounts a robust response to host oxidative stress to avoid host iron-mediated defence mechanisms. In parallel, we provide evidence that invasive non-typhoidal Salmonella employs several strategies to impair DC functions and undertake alternative nutrient scavenging strategies to survive in the hostile intracellular environment.