Project description:Treatment of urinary tract infections is today a challenge due to the increasing prevalence of multidrug-resistant ESBL-producing uropathogenic Escherichia coli (UPEC). There is an urgent need for new treatment strategies for multidrug-resistant UPEC and preferably with targets that have low potential for development of resistance. Carbon monoxide-releasing molecules (CORMs) are novel and potent antibacterial agents. The present study examines the transcriptomic targets of CORM-2 in a multidrug-resistant ESBL-producing UPEC isolate (ESBL7) in response to a single exposure to CORM-2 and after repeated exposure to CORM-2. The bacterial viability and minimal inhibitory concentration (MIC) were also examined after repeated exposure to CORM-2. Microarray analysis revealed that a wide range of processes were affected by CORM-2, including a general trend of down-regulation in energy metabolism and biosynthesis pathways and up-regulation of the SOS response and DNA repair. Several genes involved in virulence (ibpB), antibiotic resistance (marAB, mdtABC) and biofilm formation (bhsA, yfgF) were up-regulated, while some genes involved in virulence (kpsC, fepCEG, entABE), antibiotic resistance (evgA) and biofilm formation (artIP) were down-regulated. Repeated exposure to CORM-2 did not alter the gene expression patterns, the growth inhibitory response to CORM-2 or the MIC values for CORM-2, cefotaxime, ciprofloxacin and trimethoprim.
Project description:The emergence of colistin resistance in carbapenem-resistant and extended-spectrum ß-lactamase (ESBL)-producing bacteria is a significant threat to human health, and new treatment strategies are urgently required. Here we investigated the ability of the safe-for-human use ionophore PBT2 to restore antibiotic sensitivity in several polymyxin-resistant, ESBL-producing, carbapenem resistant Gram-negative human pathogens. PBT2 was observed to resensitize Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa to last-resort polymyxin class antibiotics, including a ‘next generation’ polymyxin derivative, FADDI-287. To gain additional insight into the potential mechanism of action of PBT2, we analyzed the transcriptome of K. pneumoniae and E. coli in the presence of sub-inhibitory concentrations of PBT2. Treatment with PBT2 was associated with multiple stress responses in both K. pneumoniae and E. coli. Significant changes in the transcription of transition metal ion homeostasis genes were observed in both strains.
Project description:The present study examines changes in global gene expression patterns and in virulence factor-associated genes in an extended spectrum beta-lactamase (ESBL)-producing UPEC (ESBL019) during the morphologic transitions induced by an ineffective antibiotic and in the presence of human primary bladder epithelial cells. The morphological shifts induced by ineffective antibiotics are associated with significant transcriptional virulence alterations in ESBL-producing UPEC, which may affect survival and persistence in the urinary tract.
Project description:Escherichia coli bloodstream infections are common and associated with high mortality. A key feature of E. coli is the lipopolysaccharide (LPS) O-antigen, which contributes to immune evasion during invasive infection. We analyzed serial E. coli isolates from patients with relapsed bacteremia and identified frequent disruption of O-antigen synthesis due to mutations in wbbL, resulting in a rough LPS (R-LPS) phenotype. E. coli with rough LPS isolates were more serum sensitive and less pathogenic in mice. Despite this apparent attenuation, 11 of 66 (18%) E. coli sequence type 131 bloodstream isolates in our cohort lacked O-antigen and were associated with significantly worse clinical outcomes, including septic shock and mortality. Using a recurrent bacteremia model, we show that R-LPS isolates partially evade protective immunity generated against smooth-LPS E. coli, highlighting the importance of host immune context in invasive disease.
