Ciprofloxacin is one of the most widely used antibiotics for the treatment of several infections caused by Gram-negative bacteria, like E. coli. Changes in gyrA, encoding GyrA subunit of DNA gyrase, cause the resistance to ciprofloxacin. Some ciprofloxacin resistant gyrA mutants acquired constitutive expression of marRAB operon due to the gaining mutations in marR, a repressor of this operon...

   Ciprofloxacin is one of the most widely used antibiotics for the treatment of several infections caused by Gram-negative bacteria, like E. coli. Changes in gyrA, encoding GyrA subunit of DNA gyrase, cause the resistance to ciprofloxacin. Some ciprofloxacin resistant gyrA mutants acquired constitutive expression of marRAB operon due to the gaining mutations in marR, a repressor of this operon...

The objective of this study was to evaluate collateral sensitivity and cross-resistance antibiotic-induced resistant Salmonella Typhimurium various antibiotics. S. ATCC 19585 (STWT) exposed ciprofloxacin, gentamicin, kanamycin, tetracycline induce antibiotic resistance, respectively, assigned as STCIP, STGEN, STKAN, STTET. susceptibilities the mutants cefotaxime, chloramphenicol, polymyxin B, s...

MarA activates two membrane dependent mechanisms of resistance to different antibiotics, such as ciprofloxacin and tetracycline, including promotion of outflux and inhibition of influx of antibiotics. Thus, MarA causes multiple antibiotic resistance phenotype. The activation of these mechanisms needs overexpression of marA. This could happen through mutation in marR. Thus, the aim of this study...

A bacterium's fitness relative to its competitors, both in the presence and absence of antibiotics, plays a key role ecological success clinical impact. In this study, we examine whether tetracycline‐resistant mutants are less fit drug than their sensitive parents, cost resistance is constant or variable across independently derived lines. Tetracycline‐resistant lines suffered, on average, redu...

MarA activates two membrane dependent mechanisms of resistance to different antibiotics, such as ciprofloxacin and tetracycline, including promotion of outflux and inhibition of influx of antibiotics. Thus, MarA causes multiple antibiotic resistance phenotype. The activation of these mechanisms needs overexpression of marA. This could happen through mutation in marR. Thus, the aim of this study...

mara activates two membrane dependent mechanisms of resistance to different antibiotics, such as ciprofloxacin and tetracycline, including promotion of outflux and inhibition of influx of antibiotics. thus, mara causes multiple antibiotic resistance phenotype. the activation of these mechanisms needs overexpression of mara. this could happen through mutation in marr. thus, the aim of this study...

Low-cost and rescue treatments for Helicobacter pylori infections involve combinations of several drugs including tetracycline. Resistance to tetracycline has recently emerged in H. pylori. The 16S rRNA gene sequences of two tetracycline-resistant clinical isolates (MIC = 64 microg/ml) were determined and compared to the consensus H. pylori 16S rRNA sequence. One isolate had four nucleotide sub...

A genetic basis for tetracycline resistance in cutaneous propionibacteria was suggested by comparing the nucleotide sequences of the 16S rRNA genes from 16 susceptible and 21 resistant clinical isolates and 6 laboratory-selected tetracycline-resistant mutants of a susceptible strain. Fifteen clinical isolates resistant to tetracycline were found to have cytosine instead of guanine at a position...

In Escherichia coli K-12, amplifiable resistance to tetracycline, chloramphenicol, and other unrelated antibiotics was mediated by at least four spatially separated loci. Tetracycline-sensitive mutants were isolated by Tn5 insertional inactivation of an amplified multiply resistant strain. One of these, studied in detail, showed coordinate loss of expression of all other resistance phenotypes. ...