These are the newest of the commonly used antibiotics. They have been an extremely important addition to the armamentarium for the therapy of hospital-acquired infections in light of increasing resistance to penicillins and cephalosporins. They also have been favored over the considerably more toxic aminoglycosides. However, after only 20 years of usage, resistance is increasing and new agents are being very aggressively marketed, in particular for community respiratory tract infections – by far the largest “market” owing to liberal prescribing practices.

Because of their predominantly anti-Gram negative activity, historically, ciprofloxacin, norfloxacin and ofloxacin have been most commonly used for the therapy of urinary tract infections. Recently however, ciprofloxacin has been actively marketed to surgeons for the therapy of GI infections. Its activity against enteric gram negative bacilli, oral absorption and low toxicity have made it very attractive. Most Canadian hospitals have seen large increases in surgical use of fluoroquinolones in the last few years. Worries of increasing “pressure” on hospital Gram negatives and subsequent resistance development from this high volume use is a worry.

In the last few years three new fluoroquinolones have been marketed – levofloxacin (the levo-rotatory isomer of ofloxacin), moxifloxacin and gatifloxacin. They have been referred to by the companies as “respiratory” fluoroquinolones for obvious reasons. However, clinical studies have been performed in many different types of infections and label indications are broad. Moxifloxacin is more active against Staphylococci, Streptococci and anaerobes than ciprofloxacin. Unfortunately resistance development tends to confer resistance to the whole class though there is variability. I feel these important agents should be used very carefully to preserve their utility for serious infections.

Category: Antibiotics

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