We have examined the antipneumococcal mechanisms of a series of novel fluoroquinolones that are identical to ciprofloxacin except for the addition of a benzenesulfonylamido group to the C-7 piperazinyl ring. A number of these derivatives displayed enhanced activity against Streptococcus pneumoniae strain 7785, including compound NSFQ-105, bearing a 4-(4-aminophenylsulfonyl)-1-piperazinyl group ...

AcrAB-TolC is a major efflux pump in Escherichia coli. It was reported that tolC is overexpressed and involves in improving the organic solvent tolerance level in Escherichia colimarR mutants that are resistant to several antibiotics, such as ciprofloxacin. Low and intermediate levels resistance did not improve organic solvent tolerance. Thus, it was decided to measure tolC expression and organ...

Germination of Bacillus anthracis spores occurs when nutrients such as amino acids or purine nucleosides stimulate specific germinant receptors located in the spore inner membrane. The gerP(ABCDEF) operon has been suggested to play a role in facilitating the interaction between germinants and their receptors in spores of Bacillus subtilis and Bacillus cereus. B. anthracis mutants containing del...

HE tryptophan ( t rp) operon of Salmonella typhimurium consists of five Tstructural genes regulated as a unit by tryptophan (BLUME and BALBINDER 1966; BAUERLE and MARGOLIN 1966a, 196613; BLUME, WEBER and BALBINDER 1968). The biosynthetic reactions involved and the order of the genes (see Figure 1 ), as well as the regulation of the trp operon have been shown to be identical in Escherichia coli ...

5',5',5'-Trifluoro-dl-leucine inhibited the activity of alpha-isopropylmalate synthetase (the initial enzyme unique to leucine biosynthesis) as well as the growth of Salmonella typhimurium. Mutants of S. typhimurium resistant to the analogue were isolated and characterized. In most cases, they overproduced and excreted leucine or leucine, valine, and isoleucine as a result of an alteration in t...

We evaluated the in vitro activity of delafloxacin against a panel of 117 Neisseria gonorrhoeae strains, including 110 clinical isolates collected from 2012 to 2015 and seven reference strains, compared with the activities of seven antimicrobials currently or previously recommended for treatment of gonorrhea. We examined the potential for delafloxacin to select for resistant mutants in ciproflo...

Multidrug resistance (MDR) in Enterobacter aerogenes can be mediated by induction of MarA, which is triggered by certain antibiotics and phenolic compounds. In this study, we identified the gene encoding RamA, a 113-amino-acid regulatory protein belonging to the AraC-XylS transcriptional activator family, in the Enterobacter aerogenes ATCC 13048 type strain and in a clinical multiresistant isol...

The operon encoding the general stress transcription factor sigma(B) and two proteins of its regulatory network, RsbV and RsbW, was cloned from the gram-positive bacterium Bacillus anthracis by PCR amplification of chromosomal DNA with degenerate primers, by inverse PCR, and by direct cloning. The gene cluster was very similar to the Bacillus subtilis sigB operon both in the primary sequences o...

Mutant phoR cells show a clonal variation phenotype with respect to bacterial alkaline phosphatase (BAP) synthesis. BAP clonal variation is characterized by an alternation between a Bap+ and Bap- phenotype. The switching is regulated by the phoM operon and the presence of glucose; the pho-510 mutant form of the phoM operon abolishes both BAP clonal variation and the effect of glucose (B.L. Wann...

OBJECTIVES The objective of this study was to determine the fitness of Escherichia coli mutants with reduced susceptibility to tigecycline after exposure to adverse conditions in vitro and in vivo. METHODS Survival in response to low pH, bile salts, oxidative stress and human serum was examined for E. coli mutants with reduced susceptibility to tigecycline due to single mutations that caused ...