PubMed · 10987743
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K P Klugman. 2000. Levofloxacin-resistant pneumococcus.. https://doi.org/10.1086/313958
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Several novel metal-quinolone compounds have been synthesized and characterized by analytical, spectroscopic and X-ray diffraction methods. The crystal structure of the four compounds, Na(2)[(Cd(Cx)3)(Cd(Cx)3(H2O))].12H2O, [Co(Cp)2(H2O)2].9H2O, [Zn(Cp)2(H2O)2].8H2O and [Cd(HCp)2(Cl)2].4H2O, is presented and discussed: HCx=1-ethyl-1,4-dihydro-4-oxo(1,3)-dioxolo(4,5-g)cinnoline-3-carboxylic acid and HCp=1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid. In all these compounds the quinolone acts as a bidentate chelate ligand that binds through one carboxylate oxygen atom and the exocyclic carbonyl oxygen atom. Complexes of ciprofloxacin were screened for their activity against several bacteria, showing activity similar to that of the ligand. In addition, the number of bacteria killed after 3 h of incubation with the ligand, [Co(Cp)2(H2O)2].9H2O, Ni(Cp)2.10H2O and Cu(Cp)2.6H2O, was determined against S. aureus ATCC25923. There is a direct relationship between the growth rate and the lethal rate. Against growing bacteria, the ligand is the most bactericidal and Cu(Cp)2.6H2O is the less bactericidal. On the contrary, against non-dividing bacteria, the complexes were more bactericidal than the ligand, with Cu(Cp)(2).6H(2)O the most bactericidal compound.
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The prevalence of hemolysin, type 1 fimbriae, P fimbriae, cytotoxic necrotizing factor-1 (CNF-1), aerobactin, and autotransporter toxin (sat) was analyzed by polymerase chain reaction and phenotypic assays of 42 epidemiologically unrelated Escherichia coli strains causing acute pyelonephritis in women (21 nalidixic acid-susceptible and 21 nalidixic acid-resistant strains) and 58 E. coli strains causing cystitis in women (29 nalidixic acid-susceptible and 29 nalidixic acid-resistant strains). Hemolysin and CNF-1 were less prevalent (P<.05) in nalidixic acid-resistant than in nalidixic acid-susceptible E. coli strains from patients with either pyelonephritis (14.3% vs. 52.4%) or cystitis (0% vs. 31.0%). Among E. coli strains causing cystitis, type 1 fimbriae expression was less prevalent (P<.05) in the nalidixic acid-resistant group (55.2%) than in the nalidixic acid-susceptible group (86.2%). None of the nalidixic acid-resistant and 20.7% of the nalidixic acid-susceptible strains causing cystitis showed the proteolytic toxin Sat (P<.05). These results suggest that resistance to quinolones may be associated with a decrease in the presence or the expression of some virulence factors in uropathogenic E. coli.