[Prerequisites for enhancement of the efficacy of fosfomycin by glucose-6-phosphate in treatment of experimentally infected animals (author's transl)]

In chemotherapy of otherwise fatally infected mice (intraperitoneally) the effective dose50 (ED50) of fosfomycin (2 single doses, subcutaneous application 1 and 6 h post infect.) was decreased significantly by supplementing the antibiotic solution with 100 mg glucose-6-phosphate (G-6-P) per kg animal and per injection if also the MIC of the infecting strain (Klebsiella oxytoca and K. aerogenes II) was lowered by addition of G-6-P (25 mg/l) to the nutrient medium (Table 1 and 2). With strains not exhibiting any influence on the MIC no such effect was observed (Table 1). From this it is concluded that the enhancement of antimicrobial activity of fosfomycin in vivo is based on the same mechanism as in vitro. This mechanism is the initiation of a second route of transportation into the bacterial cell (7), the hexose-6-phosphate transport system that apparently is inducible not only in vitro but also in vivo. Blood levels of G-6-P sufficient or above to induce this system in vitro (5 mg/l) were being held with doses of 100 mg/kg body weight in dogs during 70 to 120 min (Fig. 3) and 45 to 70 min (Fig. 4) when applied subcutaneously or intravenously respectively. These periods of contact area adequate to induce a considerable decrease of the MIC. With the strain used (K. oxytoca) the MIC of 128 mg/l was lowered by contact with G-6-P during 60 or 120 min to 16 or 8 mg/l respectively (Fig. 5). For full induction of the hexose-6-phosphate system resulting in a MIC of 2 mg/l however, 8 h were necessary. From the above findings it is concluded that clinical studies are necessary. As G-6-P is a (short-lived) physiological product of cell metabolism and nontoxic such studies are justifiable in cases where therapeutic use of fosfomycin can be regarded as an indication.

[Comparison of in vitro methods for the determination of the activity of fosfomycin with the efficacy determined in experimentally infected mice (author's transl)]

Effective doses of fosfomycin against 17 strains of bacteria were determined in therapeutic experiments using infected mice. The peak serum levels obtained after administration of these doses were compared with the minimum inhibitory concentrations determined in vitro. Reasonable minimum inhibitory concentrations were obtained only with Mueller-Hinton agar containing glucose-6-phosphate: 1. Correlation of in vivo and in vitro efficacy is much better in comparison with the use of media without glucose-6-phosphate. 2. Minimum inhibitory concentrations below the levels obtained after therapeutic doses were found only in Mueller-Hinton agar containing glucose-6-phosphate. 3. Minimum inhibitory concentrations are better reproducible when determined on solid media than in broth.

Experimental endocarditis caused by Streptococcus sanguis: single and combined antibiotic therapy

The effectiveness of penicillin G, fosfomycin, and cefoxitin alone and in combination was studied in vitro and in the treatment of left-sided Streptococcus sanguis endocarditis in rabbits. In vitro, the combinations penicillin G plus fosfomycin, penicillin G plus cefoxitin, and fosfomycin plus cefoxitin were synergistic or partially synergistic for S sanguis. Therapy with the combinations was more effective in eradicating the species from cardiac vegetations that was that with each antibiotic used alone.

[Clinical experience with fosfomycin in urinary tract infections (author's transl)]

Fosfomycin, an antibiotic from a new class of substances, has a bactericidal action against a broad spectrum of gram-positive and gram-negative organisms. The efficacy of fosfomycin in urinary tract infections was investigated with a dose of 15 g/day. 52 urological patients with obstructive and non-obstructive infections of the urinary tract were accepted for the study. The therapeutic success was convincing: 91% of the pathogens were eliminated from the urine, the urine was free from organisms in 84% of the patients after the treatment. 93% were clinically symptomless. The effects against Pseudomonas was very good: 8 of 9 strains present were eliminated. Unpleasant gastrointestinal side effects occurred which were dependent on the rate of infusion and usually became tolerable at a slower rate.

[Chemotherapy with fosfomycin, cefoxitin, and cefotaxime in experimental E. coli-pleuropneumonia (author's transl)]

Two models of pneumonia--the experimental E. coli-pleuropneumonia and "intrapulmonary" E. coli-pneumonia--were employed in these studies. Only fosfomycin was effective in both models even at the low dosage of 100 mg/kg/d. The comparative drugs cefotaxime and cefoxitin, however, were not able to reduce the bacteria in both lungs even at very high dosages of 900 mg/kg and 300 mg/kg per day respectively over 6 days.

Fosfomycin penetration into the cerebrospinal fluid of patients with bacterial meningitis

A comparative study was made of the penetration of fosfomycin, penicillin G, ampicillin and chloramphenicol into the cerebrospinal fluid of patients with meningitis treated with combinations of fosfomycin and one of the other three antibiotics. Minimal inhibitory concentrations and in vitro interaction of these antibiotics against Streptococcus pneumoniae and Neisseria meningitidis strains were determined. 90-96.5% of these strains were sensitive to penicillin G, 95-96.5% to ampicillin, 85-100% to chloramphenicol and 90-100% to fosfomycin. Fosfomycin shows a more marked synergism with penicillin G or ampicillin than with chloramphenicol against both bacterial species. The percentages of penetration into the cerebrospinal fluid were: chloramphenicol, 32%; fosfomycin, 25.7%; ampicillin, 15.9%, and penicillin G, 7.9%. The clinical results show that the combination of fosfomycin + penicillin G or fosfomycin + ampicillin can be an alternative in the treatment of meningitis produced by moderately susceptible strains of S. pneumoniae and N. meningitidis to penicillin G and ampicillin.

In vitro and in vivo antibacterial activities of FR-31564, a new phosphonic acid antibiotic

FR-31564, a new phosphonic acid antibiotic, was active against most Gram-negative bacteria except Serratia marcescens and glucose-nonfermenting Gram-negative rods excluding Pseudomonas aeruginosa. The antibacterial activity in vitro of FR-31564 was stronger than that of fosfomycin especially against Escherichia coli, Klebsiella pneumoniae, Enterobacter species and P. aeruginosa. FR-31564 also was active against Gram-negative bacteria resistant to beta-lactam antibiotics and against gentamicin-resistant strains of P. aeruginosa. The antibacterial activity in vitro of FR-31564, like that of fosfomycin, was enhanced when 10% rabbit blood was added to the nutrient agar. The therapeutic efficacy of FR-31564 in experimental infections in mice was superior to that of fosfomycin in infections due to most Gram-negative bacteria used, and was similar to that of gentamicin in infections due to Citrobacter freundii, Proteus rettgeri and Proteus inconstans B. The protective effect of FR-31564, particularly in the P. aeruginosa infection, was superior to that of other control drugs including gentamicin.

Fosfomycin therapy of experimental infections in mice

Fosfomycin inhibits the development of severe pyogenic infection by Staphylococcus aureus in kidneys if administered during establishment of infection. It inhibits the development of lethal infection by Escherichia coli. It has a positive therapeutic effect on listeria infection in mice even with a fosfomycin resistant mutant.

[Ambulatory therapy with fosfomycin in dentistry and stomatology]

1-2 g/day or 3-4 g/day phosphomycin were administered per os to children and adults respectively for an average of 5.2 days in the outpatient treatment of 28 males and 18 females with parodontitis, gingivitis and dysodontiasis of bacterial origin. All patients presented swelling of the soft parts and 34 (74%) had hyperpyrexia. A clinical cure was obtained after 9 days in all cases. Fever lasted an average of 2.4 days and disappeared after 6 days. Swelling lasted an average of 3.6 days and disappeared after 8 days. Tolerance was excellent. Two patients (4.3%) displayed diarrhoea and nausea and one (2.2%) pruritus. These side-effects did not necessitate the suspension of treatment. It is felt that phosphomycin may be regarded as a drug of choice in the treatment of odontostomatological infection of bacterial origin.

[Antibacterial activity of fosfomycin in chronic kidney infections]

Authors have carried out a retrospective study in vitro on the bacteria isolated from renal parenchyma and stones in patients with CPN associated to kidney stones. Results show a different inhibitory action of the some antibiotics to Proteus, E. coli and P. aeruginosa. Fosfomycin inhibits the growth of bacteria in a wide range of concentration (50-1000 microgram/ml). A prospective study in vivo shows an excellent therapeutic action of fosfomycin in recurrent urinary infections, and a very good one in CPN and in some forms associated to kidney stones.