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Luitwieler, S. H.

Publications and source records attributed to Luitwieler, S. H..

2 recordsLinked to original sources

Genetic Adaptation to Amoxicillin in Escherichia coli: The Limited Role of dinB and katE

Bacteria can quickly adapt to sub-lethal concentrations of antibiotics. Several stress and DNA repair genes contribute to this adaptation process. However, the pathways leading to adaptation by acquisition of de novo mutations remain poorly understood. This study explored the roles of DNA polymerase IV (dinB) and catalase HP2 (katE) in E. colis adaptation to amoxicillin. These genes are thought to play essential roles in beta-lactam resistance - dinB in increasing mutation rates and katE in managing oxidative stress. By comparing the adaptation rates, transcriptomic profiles, and genetic changes of wild-type and knockout strains, we aimed to clarify the contributions of these genes to beta-lactam resistance. While all strains exhibited similar adaptation rates and mutations in the frdD gene and ampC operon, several unique mutations were acquired in the {Delta}katE and {Delta}dinB strains. Overall, this study distinguishes the contributions of general stress-related genes on the one hand, and dinB, and katE on the other hand, in development of beta-lactam resistance.

microbiology↗

Fluoroquinolone-Specific Resistance Trajectories in E. coli and their Dependence on the SOS-Response

Fluoroquinolones are essential for treating bacterial infections in both human and veterinary medicine. This study investigates the mechanisms behind acquired resistance to fluoroquinolones with a specific focus on the SOS response - a critical cellular pathway activated by DNA damage. Utilizing an experimental evolution approach, we exposed Escherichia coli to four fluoroquinolones and monitored the adaptation process. A recA knock-out mutant deficient in the SOS response was used as biological control. The emergence of resistance was accompanied by numerous DNA mutations, consisting of some observed often and others that infrequently appeared. Our findings indicate that the development of resistance depends in varying degrees on the SOS response among the tested fluoroquinolones, with notable dissimilarities in clinical resistance development. Resistance developed slowest to ciprofloxacin, then levofloxacin, followed by enrofloxacin, and fastest to moxifloxacin. Genomic analysis revealed distinct mutation profiles in cultures exposed to the tested antimicrobials, emphasizing the unique adaptation strategies of bacteria. This research underscores the importance of recognizing the differences among fluoroquinolones in scientific research and clinical practice.

microbiology↗