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Imirzalioglu, C.

Publications and source records attributed to Imirzalioglu, C..

2 recordsLinked to original sources

Rapid clinical metagenomics enables early tailored therapy in complicated urinary tract infections and strengthens antimicrobial stewardship

Rapid and accurate diagnosis of UTIs remains difficult because culture-based methods are slow and less sensitive. This study evaluates URINN, a metagenomic workflow that detects uropathogens, antibiotic resistance genes, and virulence factors directly from patient urine samples. The optimized protocol was tested on a combined set of 349 clinical urine samples. URINN demonstrated 99% accuracy across all samples and 97% sensitivity for identifying 294 pathogens, including both bacteria and fungi. It predicted antibiotic susceptibility with 91% accuracy across 2099 antibiotics. The method detected pathogens at concentrations as low as 9.3 x 103 CFU/mL and provided results within approximately four hours. Flow cytometry and DNA yield analyses helped establish thresholds to differentiate culture-positive from culture-negative samples, with genome coverage linked to the accuracy of susceptibility predictions for certain species. Virulence profiling revealed that adherence and nutritional factors are crucial for colonization and persistence. Leukocyte counts were comparable between genders, but bacterial loads were higher in females. The catheterized group had significantly higher leukocyte counts, and their urine showed increased cephalosporin resistance. This approach could enhance clinical decision-making, support personalized treatment, and improve the management of complicated UTIs, thereby contributing to better UTI care and antibiotic stewardship.

genomics↗

A single residue within the MCR-1 protein confers anticipatory resilience

The envelope stress response (ESR) of Gram-negative enteric bacteria senses fluctuations in nutrient availability and environmental changes to avert damage and promote survival. It has a protective role towards antimicrobials but direct interactions between ESR components and antibiotic resistance genes have not been demonstrated. Here we report specific interactions between the two-component conjugative pilus expression (Cpx)RA signal transduction system and the recently described mobile colistin resistance (MCR-1) protein. Purified MCR-1 is specifically cleaved by the serine endoprotease DegP within a structurally conserved periplasmic bridging domain. Cleavage-site mutations in MCR-1 render derivatives either protease-resistant or degradation-susceptible with widely differing consequences for colistin resistance. Transfer of the degradation-susceptible mutant to strains that lack either DegP or its regulator CpxRA restores expression and colistin resistance. MCR-1 production in Escherichia coli induces a Cpx-dependent ESR and imposes growth restriction in strains lacking either DegP or CpxRA, effects that are reversed by transactive expression of DegP. MCR-1 production impairs bacterial motility indicating dissipation of cytoplasmic transmembrane potential. Indeed, growth in media with low pH dramatically increases both MCR-1-dependent phosphoethanolamine (PEA) modification of lipid A as well as colistin-resistance activity. In vitro transferase- and lipid A reconstitution-assays demonstrate that MCR-1 is highly active at acidic pH. Acquiring MCR-1 also renders strains more resistant to antimicrobial peptides. Thus, a conserved motif within MCR-1 induces components of the ESR to confer resilience to stimuili commonly encountered in the environment such as to changes in pH and towards antimicrobial peptides. Excipient allosteric activation of the DegP protease specifically inhibits growth of isolates carrying mcr-1 plasmids indicating that a targeted strategy can lead to the elimination of transferable colistin resistance in Gram-negative bacteria.

microbiology↗