Nitrofurantoin advocated for treatment of cystitis. (Seven-Day Course).

ST. LOUIS--A 7-day course of nitrofurantoin is hard to beat for cystitis in women, according to Dr. Sebastian Faro, professor of ob.gyn. at the University of Texas, Houston.

"I'll be honest with you. This drug is my favorite. At 100 mg q.i.d., it's well tolerated. Tissue levels are nonexistent, blood 1evels are low. You get very high levels in the urine. And nitrofurantoin doesn't affect the vaginal flora," he said at the 12th International Pelvic Reconstructive and Vaginal Surgery Conference.

A particularly attractive feature of nitrofurantoin in postoperative patients is that the drug won't mask soft-tissue infection, bacteremia, or respiratory tract infection.

This is a drug, however, that has to be given for a full 7 days. There is no persuasive evidence that shorter courses are adequate for cystitis, Dr. Faro said at the meeting, which was sponsored by the Society of Pelvic Reconstructive Surgeons.

Nitrofurantoin is active against Escherichia coli, the cause of most cases of cystitis. That's crucial, since roughly 40% of all isolates of E. coli are now ampicillin resistant and 20% show resistance to trimethoprim-sulfamethoxazole.

Nitrofurantoin also has good activity against Enterobacter, Streptococcus, Staphylococcus, Enterococcus, and Klebsiella. It is definitely not active against Proteus or Pseudomonas. However, Pseudomonas cystitis is unlikely, except in a chronically catheterized patient who has been in an ICU.

One of nitrofurantoin's best qualities is that it is urine specific. It doesn't exert selective pressure on bacteria located in other bodily ecosystems; hence it doesn't promote bacterial resistance.