Gatifloxacin 200 mg or 400 mg once daily is as effective as ciprofloxacin 500 mg twice daily for the treatment of patients with acute pyelonephritis or complicated urinary tract infections

The efficacy and safety of two oral dosing regimens of gatifloxacin were compared to ciprofloxacin in the treatment of complicated urinary tract infection in a randomised, double-blind multi-centre trial. One thousand one hundred and twenty-three adult patients with complicated urinary tract infection (70%) or pyelonephritis (30%) were initially enrolled, 1122 were treated. Of these, 824 were included in a modified ITT population: gatifloxacin 200 mg (274 patients) or 400 mg (280 patients) once daily or ciprofloxacin 500 mg twice daily for 5-14 days (269 patients). Bacteriological and clinical responses were assessed 7-9 days after the end of treatment (EOT) and 4-6 weeks post-treatment (end of study visit, EOS). The bacteriological response rates per patient at EOT in the gatifloxacin 400 mg, gatifloxacin 200 mg and ciprofloxacin groups were 77% (207/269), 78% (208/268) and 73% (190/259), respectively. At EOS they were slightly lower: 70% (184/262), 71% (176/248) and 69% (174/252), respectively. The clinical responses at EOT were 69% (190/277), 70% (190/273) and 65% (174/266). At EOS they were 71% (193/273), 70% (182/259) and 74% (190/258). The overall eradication rates of initial pathogens at EOT and EOS were 85.3% and 88.4% in the gatifloxacin 400 mg group; 84.1 and 90.1% in the gatifloxacin 200 mg group and 85.1 and 91.4% in the ciprofloxacin group. Both oral regimens of gatifloxacin were as effective as that of ciprofloxacin. All treatment groups showed a similar safety profile, nausea being the most frequently reported adverse event.

Gatifloxacin 400mg as a single shot or 200mg once daily for 3 days is as effective as ciprofloxacin 250mg twice daily for the treatment of patients with uncomplicated urinary tract infections

The efficacy and safety of two oral dosing regimens of gatifloxacin compared with ciprofloxacin for the treatment of acute uncomplicated lower urinary tract infection was investigated in a double-blind, randomised study, in adult female patients who received either gatifloxacin (400 mg as a single shot or 3 days of 200 mg once daily) or ciprofloxacin (250 mg given twice daily for 3 days). Bacteriological and clinical responses were assessed 7-9 days after the end of treatment (EOT), and 4-6 weeks post-treatment (end of study, EOS). One thousand one hundred and two women were treated, 741 (248 in the gatifloxacin 400 mg group, 252 in the gatifloxacin 200 mg group, and 241 in the ciprofloxacin group) presented with bacteriological proof of infection and entered the efficacy analysis. The bacteriological response per patient at EOT in the three groups were 80% (177/220) [95% CI to ciprofloxacin -8.4%; 6.4%], 83% (184/222) [95% CI to ciprofloxacin -5.9%; 8.7%] and 81% (176/216), respectively. At the follow-up assessment they were slightly lower, 75% (167/224), 79% (169/213) and 79% (171/217), respectively. The clinical responses at EOT were 81% (197/243) [95% CI to ciprofloxacin -10.2%; 3.4%], 85% (213/250) [95% CI to ciprofloxacin -5.7%; 7.2%] and 85% (201/238), respectively. At EOS they were 82% (195/239), 88% (212/241) and 86% (200/233), respectively. The eradication rates for all initial pathogens at the EOT were 90.3% in the gatifloxacin 400 mg S.D. group, 90.6% in the gatifloxacin 200 mg group, and 88.3% in the ciprofloxacin group. All treatment groups showed a similar safety profile. The incidence of treatment-related adverse events was comparable, the majority of adverse events were of mild or moderate intensity and the medications were well tolerated. Both the administration of gatifloxacin 200 mg once daily for 3 days, and gatifloxacin 400 mg as a single shot were shown to be equivalent to ciprofloxacin 250 mg twice daily for 3 days for the treatment of acute uncomplicated lower urinary tract infections.

New synthetic siderophores and their beta-lactam conjugates based on diamino acids and dipeptides

Linking of siderophores to antibiotics improves the penetration and therefore increases the antibacterial activity of the antibiotics. We synthesized the acylated catecholates and hydroxamates as siderophore components for antibiotic conjugates to reduce side effects of unprotected catecholate and hydroxamate moieties. In this paper, we report on bis- and tris-catecholates and mixed catecholate hydroxamates based on diamino acids or dipeptides. These compounds were active as siderophores in a growth promotion assay under iron limitation. Most of the conjugates with beta-lactams showed high in vitro activity against Gram-negative bacteria especially Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Stenotrophomonas maltophilia. The compounds with enhanced antibacterial activity use active iron uptake routes to penetrate the bacterial outer membrane barrier, demonstrated by assays with mutants deficient in components of the iron transport system. Correlation between chemical structure and biological activity was studied.

8-Acyloxy-1,3-benzoxazine-2,4-diones as siderophore components for antibiotics

8-Acyloxy-1,3-benzoxazine-2,4-diones as masked catechol derivatives represent a novel type of siderophore components, whose growth promoting activity is low or not existing if tested alone. But after conjugation with beta-lactam antibiotics the resulting conjugates show a significantly increased antibacterial activity against Gram-negative bacteria compared with their parent antibiotics. Investigations using a set of penetration and iron transport mutants demonstrated that the conjugates use iron transport systems to penetrate the bacterial outer membrane. Title compounds were synthesized from (2,3-dimethoxycarbonyloxy)-benzoic acid and different amino compounds. Conjugates with penicillins and cephalosporins were prepared.

[Survival capacity of genetically altered Escherichia coli strains. 2. Survival of pure cultures in different water and soil matrices]

The survival of two genetically engineered E. coli strains (L+, CAG+) compared to that of 4 control strains (N0, K12, L-, CAG-), was investigated in drinking water, surface water, sewage and soil under different conditions. Both genetically manipulated strains are able to produce Prourokinase, an anticoagulant. It was found, that all strains died off inspite of high inoculated bacterial densities. In drinking water, no bacteria could be recultivated immediately following inoculation. Upon inoculation in surface water, the genetically manipulated strains L+ and CAG+ were more sensitive than the other strains. The same was found for sewage under aerobic conditions, whereby, the control strains N0 and K12 as well as the wild-strains of the genetically manipulated organisms, L- and CAG- survived the whole experimental period and kept their numbers at a level between 100 and 1000 CFU/ml. Under anaerobic conditions, a die-off of all tested strains was similarly registered with time. The influence of the autochthonous microflora of sewage water could be documented in that, under these conditions, all test strains survived the whole experimental period of 31 days with the exception of the genetically manipulated strain CAG+. In soil experiments, it was found that the humus-rich garden soil was more effective in eliminating the E. coli strains than sand. The antagonistic effect of the autochthonous soil microflora was only clearly seen in experiments with garden soil. However, these results did not meet the expectations for the two CAG strains, for which a longer survival period had been previously established for in nutrient rich soil. In contrast to the E. coli control strains N0 and K12, the two L strains and the CAG+ strain survived the whole test period of 36 days. It can be concluded that under these simulated environmental conditions, all tested strains of E. coli die off more or less in a short period of time following inoculation with the autochthonous microflora of environmental samples.

[Survival ability of genetically engineered strains of Escherichia coli. 1. Physiological characterization and the effect of different physiochemical conditions]

Two genetically engineered E. coli strains L+ and CAG+ possessing the ability to produce the enzyme Pro-urokinase and showing additionally ampicillin resistance, and wild-strains L- and CAG-, were characterized using 328 physiological tests. Their test profiles were compared with those of 30 clinical and nonclinical E. coli isolates. This biotyping made a differentiation and recognition of the genetically manipulated strains possible. It also allowed distinguishing them from the other tested isolates. The genetically engineered strains showed a narrower activity spectrum compared with their wild-strains. However, based on differentiating characteristics, all strains could be clearly biochemically identified as E. coli. Under different laboratory test conditions (organic load, pH, salt content, temperature), the E. coli strains showed no striking features or peculiarities with respect to their survival compared to data from literature. However, low pH (pH less than 5), high salt content (greater than 7%) as well as low (less than 8 degrees C) and high (greater than 37 degrees C) incubation temperatures clearly reduced their ability to survive. Apart from a few exceptions (e.g. survival of strain L+ at 44 degrees C and pH 7 with high cell densities), the survival of the genetically engineered strains corresponded to that of the control and wild-strains. Both CAG strains, especially the genetically manipulated strain CAG+, showed in many cases reduced viability compared with the other strains.

The magnetic properties of the nickel cofactor F430 in the enzyme methyl-coenzyme M reductase of Methanobacterium thermoautotrophicum

Cofactor 430 of methyl-coenzyme M reductase from Methanobacterium thermoautotrophicum was studied in both the extracted form in aqueous solution and protein-bound by using low-temperature magnetic-circular-dichroism spectroscopy. In both forms the nickel was present as high-spin paramagnetic nickel(II), spin S = 1, subject to almost equal zero-field splitting (cofactor F430, D = +9.0 cm-1, E/D = 0; methyl-coenzyme M reductase, D = +8.5 cm-1, [E/D[ = 0.2). This suggests identical axial co-ordination by oxygen ligand(s) both in aqueous cofactor F430 and in the investigated state of the protein.

Cloning and characterization of the methyl coenzyme M reductase genes from Methanobacterium thermoautotrophicum

The genes coding for methyl coenzyme M reductase were cloned from a genomic library of Methanobacterium thermoautotrophicum Marburg into Escherichia coli by using plasmid expression vectors. When introduced into E. coli, the reductase genes were expressed, yielding polypeptides identical in size to the three known subunits of the isolated enzyme, alpha, beta, and gamma. The polypeptides also reacted with the antibodies raised against the respective enzyme subunits. In M. thermoautotrophicum, the subunits are encoded by a gene cluster whose transcript boundaries were mapped. Sequence analysis revealed two more open reading frames of unknown function located between two of the methyl coenzyme M reductase genes.

7-Mercaptoheptanoylthreonine phosphate functions as component B in ATP-independent methane formation from methyl-CoM with reduced cobalamin as electron donor

Purified methyl-CoM reductase of Methanobacterium thermoautotrophicum (strain Marburg) catalyzed the reduction of methyl-CoM to methane with reduced cobalamin, when either synthetic 7-mercaptoheptanoylthreonine phosphate (HS-HTP) or naturally occurring component B was present. With both compounds the same maximal specific activity was obtained and ATP was neither required nor stimulatory. These findings indicate that HS-HTP functions as component B and do not support the idea that HS-HT is only active in an adenosine monophosphorylated form.

Methane formation from methyl-coenzyme M in a system containing methyl-coenzyme M reductase, component B and reduced cobalamin

Purified methyl-CoM reductase of Methanobacterium thermoautotrophicum was found to catalyze the reduction of methyl-coenzyme M to methane at a specific rate of 100 nmol X min-1 X mg protein-1 in a system containing partially purified component B, cob(III)alamin (B-12a), and, as electron donors, dithiothreitol or SnCl2. Under these experimental conditions B-12a was reduced to cob(II)alamin (B-12r), which is known to disproportionate to cob(I)alamin (B-12s) and B-12a to a slight extent. Methane formation from methyl-CoM was inhibited by propyl iodide, methyl iodide, chloroform and carbon tetrachloride, which were shown to react with B-12s to the corresponding light-sensitive alkyl cobalamin. Inhibition by propyl iodide was less effective in light-exposed samples. From these findings it is concluded that in this assay system B-12s might serve as electron donor for the enzymatic reduction of methyl-CoM to methane.

An extended-X-ray-absorption-fine-structure (e.x.a.f.s.) study of coenzyme F430 from Methanobacterium thermoautotrophicum

Coenzyme F430 is a nickel porphinoid found in all methanogenic bacteria. Extended-X-ray-absorption-fine-structure (e.x.a.f.s.) spectra have been recorded above the nickel K-edge of coenzyme F430 and two model compounds, (5,10,15,20-tetramethylporphinato) nickel(II) and (5,10,15,20-tetramethylchlorinato)-nickel(II). The results show that the four nickel-nitrogen distances in F430 are split, with two nitrogen atoms at 0.192 nm and two at 0.210 nm.