JOURNAL OF GYNECOLOGIC SURGERY© Mary Ann Liebert, Inc.

Fosfomycin Tromethamine (Monurol)

NEWTON G. OSBORNE, M.D., Ph.D.

UNCOMPLICATED URINARY TRACT INFECTIONS are estimated to cause the loss of more than seven millionwork days yearly in the United States. In December of 1996, the Food and Drug Administration (FDA)

approved for marketing fosfomycin tromethamine, the first product of a new class of antibiotics, as well asthe first one-time, one-dose antibiotic for treatment of uncomplicated urinary tract infection in women. Thisantibiotic has been available in Europe since 1988 and was used to treat over 11 million cases of uncom-plicated urinary tract infection before its approval for use in the United States.

Fosfomycin tromethamine, a fosfonic acid derivative marketed as Monurol® (Forest Pharmaceuticals,Inc., St. Louis, MO), is a single dose, oral, synthetic, broad-spectrum, bactericidal antibiotic that is effec-tive in vitro against aerobic gram-negative organisms such as Escherichia coli, Citrobacter diversus, Cit-robacter freundii, Enterobacter aerogenes, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris andSerratia marcescens. It is also active in vitro against the gram-positive cocci Enterococcus faecalis and En-terococcus faecium.

Although laboratory work suggests that fosfomycin may be effective against several species of bacteria,its only approved indication for usage is for uncomplicated urinary tract infections (cystitis) in women whoare infected with strains of E. coli or of E. faecalis, since safety and effectiveness for treating clinical in-fections with other organisms with proven in vitro susceptibility, are not yet established in adequate andwell-controlled clinical trials. Monurol is not indicated for the treatment of pyelonephritis or of perinephricabscess.

Uncomplicated urinary tract infections are one of the most common conditions gynecologists treat in theirambulatory care services. If left untreated, or if not properly treated, uncomplicated urinary tract infectionscan progress to pyelonephritis, a potentially serious complication that may cause permanent renal injury.

Recent data indicate that fosfomycin is an underrated antibiotic.1 Most microbiology surveys ofuropathogens have consistently shown that infections with E. coli strains represent more than 80% of alluropathogens recovered in cases of uncomplicated urinary tract infections. The percentages of sensitivestrains to antibiotics frequently used for the treatment of uncomplicated urinary tract infections1 are listedTable 1.

A recent report raises the possibility that fosfomycin may be effective against staphylococcal infectionsif used in combination with other drugs.2 Fosfomycin was shown to act in synergy with several anti-staphylococcal antibiotics. Among the antibiotics tested in combination with fosfomycin, there was onlyantagonism with vancomycin in two of seven isolates tested. In vitro data suggest that fosfomycin may be

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Department of Obstetrics and Gynecology, Howard University College of Medicine, Washington, DC.

Antibiotics in Gynecology

TABLE 1. ANTIBIOTIC SUSCEPTIBILITY OF ESCHERICHIA COLI STRAINS

Antibiotic Percent of strains susceptible

Ampicillin 42.25%Cefalothin 58.75%Trimethoprim/sulfamethoxazole 70.00%Amoxicillin/clavulanic acid 81.50%Ciprofloxacin 84.75%Cefuroxime 87.50%Nitrofurantoin 94.75%Fosfomycin tromethamine 95.50%

potentially useful in combination with other antistaphylococcal drugs, especially linezolid or quin-upristin/dalfopristin, for the management of staphylococcal infections.

REFERENCES

1. Garau M, Latorre A, Alonso-Sanz M. Fosfomycin: an underrated antibiotic for urinary tract infections due to E. coli.Enferm Infecc Microbiol Clin 2001;19:462.

2. Grif K, Dierich MP, Pfaller K, et al. In vitro activity of fosfomycin in combination with various antistaphylococcalsubstances. J Antimicrob Chemother 2001;48:209.

Address reprint requests to:Newton G. Osborne, M.D., Ph.D.

Department of Obstetrics/GynecologyHoward University College of Medicine

2041 Georgia Avenue NWWashington, DC 20060

E-mail: NewtonOsborne@aol.com

Journal of Gynecologic Surgery80 Osborne