Two different series of N-substituted imidazolium oximes and their monoquaternary salts were
synthesized and biologically tested with respect to their ability to inhibit growth a diverse panel of antibiotic
susceptible Gram-positive and antibiotic resistant Gram-negative bacteria as well fungal strains.
The newly synthesized compounds were analyzed by spectral studies to confirm their structure. The preliminary
results showed that all compounds tested possess promising antimicrobial potential against
both susceptible Gram-positive and antibiotic resistant Gram-negative isolates, exhibiting a wide range
of MIC values from 0.14 to 100.0 lg/mL. The structure–activity relationship demonstrates that the
p-methylphenyl and p-fluorophenyl groups in monoquaternary salts 6 and 7 attached directly to the imidazolium
ring could be essential for observed remarkable inhibitory profiles against clinically important
pathogens Pseudomonas aeruginosa (MIC = 0.14 lg/mL) and Klebsiella pneumoniae (MIC = 1.56 lg/mL).
Furthermore, the broth microdilution assay was then used to investigate the antiresistance efficacy of
compound 7 against fourteen extended-spectrum b-lactamase (ESBL)-producing strains in comparison
to eight clinically relevant antibiotics. Compound 7 exhibited a remarkable antiresistance profiles ranging
between 0.39 and 12.50 lg/mL against all of ESBL-producing strains, which leads to the suggestion that
may be interesting candidate for development of new antimicrobials to combat multidrug resistant
Gram-negative bacteria.