Project description:This study aims to determine the epidemiology of Enterobacteriaceae resistant to antibiotics of last resort in pregnant women in labour at a tertiary hospital, Pretoria, South Africa. Rectal swabs shall be used to screen for colonisation with CRE and colistin-resistant Enterobacteriales in pregnant women during labour. Carbapenem and colistin-resistant Enterobacterales can cause the following infections: bacteraemia; nosocomial pneumonia; urinary tract infections, and intra-abdominal infections. Due to limited treatment options, infections caused by these multidrug-resistant organisms are associated with a mortality rate of 40-50%. Screening for colonisation of carbapenem-resistant Enterobacteriaceae (CRE) and colistin-resistant Enterobacteriaceae will help implement infection and prevention measures to limit the spread of these multidrug-resistant organisms.
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:Drug resistance and tolerance eliminate the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. To uncover antibiotic tolerance mechanisms in biofilms, we applied stable isotope labeling with amino acids (SILAC) proteomics to selectively label and compare proteomes of sensitive and tolerant subpopulations of biofilms formed by Pseudomonas aeruginosa towards colistin, a 'last-resort' antibiotic against multidrug-resistant Gram-negative pathogens. Migration was essential in forming colistin-tolerant biofilm subpopulations, as colistin-tolerant cell-aggregates migrated with type IV pili, onto the top of killed biofilm. The colistin-tolerant cell-aggregates employed quorum sensing (QS) to initiate the formation of fresh colistin-tolerant subpopulations, highlighting multicellular behavior in antibiotic tolerance development. Erythromycin treatment which inhibits motility and QS, boosted biofilm eradication by colistin. This novel ‘-omics’ strategy to study antibiotic tolerant cells provides key insights for designing novel treatments against infections unsuppressed by conventional antimicrobials.
Project description:Objectives: Colistin remains a last-line treatment for multidrug-resistant Acinetobacter baumannii and combined use of colistin and carbapenems has shown synergistic effects against multidrug-resistant strains. In order to understand the bacterial responses to these antibiotics we analysed the transcriptome of A. baumannii following exposure to each.
Project description:Circumventing or overwhelming the bacterial adaptation capabilities is key to combatting multidrug-resistant pathogens like Pseudomonas aeruginosa. We investigated the physiological stress exerted by approved antibiotics (ciprofloxacin, levofloxacin, rifampicin, gentamicin, tobramycin, azithromycin, tigecycline, polymyxin B, colistin, ceftazidime, meropenem, piperacillin/tazobactam), experimental antibiotics (CHIR-090) and NSAIDs (acetylsalicylic acid (aspirin), diclofenac, ibuprofen), and studied the bacterial response on the proteome level. Radioactive pulse-labeling of newly synthesized proteins followed by 2D-PAGE was used to monitor the acute response of P. aeruginosa to antibiotic treatment. Subsequently, marker proteins were excised from non-radioactive gels and identified by mass spectrometry. We generated a reference library of P. aeruginosa proteomic responses and implemented a mathematical comparison of the profiles. Proteomic signatures were derived for clinically relevant target areas.
Project description:There is an urgent need for novel antibiotics against carbapenem and 3rd generation cephalosporin-resistant Gram-negative pathogens, for which the last-resort antibiotics have lost most of their efficacy. We describe here a novel class of synthetic antibiotics that was inspired from natural product-derived scaffolds. The antibiotics have an unprecedented mechanism of action, which targets the main component (BamA) of the Bam folding machinery required for folding and insertion of ß-barrel proteins into the outer membrane of Gram-negative bacteria. This OMPTA (outer membrane protein-targeting antibiotic) class shows potent activity against multidrug-resistant Gram-negative ESKAPE pathogens and overcomes colistin-resistance both in vitro and in vivo. A clinical candidate has the potential to address life threatening Gram-negative infections with high unmet medical need.
Project description:Circumventing or overwhelming the bacterial adaptation capabilities is key to combatting multidrug-resistant pathogens like Pseudomonas aeruginosa. In an effort to understand the physiological response of P. aeruginosa to clinically relevant antibiotics, we investigated the proteome after exposure to ciprofloxacin, levofloxacin, rifampicin, gentamicin, tobramycin, azithromycin, tigecycline, polymyxin B, colistin, ceftazidime, meropenem, and piperacillin/tazobactam. We further investigated the response to CHIR-90, which represents a promising class of lipopolysaccharide biosynthesis inhibitors currently under evaluation. Radioactive pulse-labeling of newly synthesized proteins followed by 2D-PAGE was used to monitor the acute response of P. aeruginosa to antibiotic treatment. Marker proteins were excised from non-radioactive gels and identified by mass spectrometry. The proteomic profiles provide insights into the cellular defense strategies for each antibiotic. A mathematical comparison of these response profiles based on upregulated marker proteins revealed similarities of responses to antibiotics acting on the same target area.
Project description:There is an urgent need for novel antibiotics against carbapenem and 3rd generation cephalosporin-resistant Gram-negative pathogens, for which the last-resort antibiotics have lost most of their efficacy. We describe here a novel class of synthetic antibiotics that was inspired from natural product-derived scaffolds. The antibiotics have an unprecedented mechanism of action, which targets the main component (BamA) of the Bam folding machinery required for folding and insertion of ß-barrel proteins into the outer membrane of Gram-negative bacteria. This OMPTA (outer membrane protein-targeting antibiotic) class shows potent activity against multidrug-resistant Gram-negative ESKAPE pathogens and overcomes colistin-resistance both in vitro and in vivo. A clinical candidate has the potential to address life threatening Gram-negative infections with high unmet medical need.