Tougher Bugs, Few New Drugs
Most cases of community-acquired MRSA are skin and soft tissue infections that are not life-threatening, but some patients are experiencing more lethal disease. In the late 1990s, four healthy children in Minnesota and North Dakota died from community-acquired infections. At Johns Hopkins Hospital, said Bartlett, four patients became critically ill this winter with pneumonia caused by community-acquired MRSA organisms: One died; two are still hospitalized. "There were 12,000 cases of MSRA reported by the prison systems in Texas and California," added Bartlett. "While most are tissue infections, 4 percent of the 12,000 had bacteremia, an invasive disease."
Bacterial resistance is a natural biological phenomenon, but it can be exacerbated by several factors, including overuse, underuse or misuse of antimicrobials and poor patient compliance. The best way to combat antimicrobial resistance, some experts say, is by reducing -- or better, eliminating -- improper use of these drugs in human and veterinary medicine. But even under the best conditions, resistance will still occur.
"If we look at history, antibiotic resistance is predictable, and we're going to need a constant inflow of new antibiotics," said Bartlett. "We've always stayed ahead of it, because we were always developing drugs. What is scary is that we're getting down to a smaller and smaller number and it takes a long time -- eight years and $900 million -- to develop an antibiotic."
The few new antibiotics that have come to market during the past few years have concentrated almost entirely on gram-positive organisms such as S. aureus. (Bacteria are identified as gram-positive or gram-negative based on a lab test on the composition of their cell walls.) Gram-negative organisms -- including pseudomonas, klebsiella and acinetobacter -- which are responsible for a large percentage of the nosocomial infections in intensive care units, have fewer new drugs to target them. This, even though they are increasingly multi-drug-resistant and notoriously difficult to treat.
The drug approval process has also become more problematic in recent years, according to Projan.
"Regulatory authorities have come under increasing public and government scrutiny," he said, pointing out how tetracycline took only two years to come on the market, while tigecycline, a new antibiotic being developed by Wyeth, has already taken 10 years to make its way through the approval process and is not likely to become available until 2005.
There are still a number of companies interested in development of new antibiotics, according to Goldhammer, and his organization has met with both the FDA and the IDSA to review some of the regulatory impediments affecting antibiotic development.
"I think we're making a lot of progress," he said. "We've had some good discussions with the FDA on the key issues in this area, and I think the FDA shares our interest in facilitating the introduction of new classes of antibiotics."
Streamlining the development and regulatory process remains the biggest challenge to bolstering the antibiotic pipeline. In the early days of the AIDS epidemic, activists successfully pressured the FDA to speed up the drug approval process. However, Bartlett thinks it is unlikely that will happen with antibiotics.
"There aren't any activists for MRSA," he noted. "Resistance isn't high up on anyone's list of priorities. The AIDS groups were very well organized and mobilized. I don't know if there's any citizen advocacy for infectious diseases."•
Roxanne Nelson is a freelance writer and registered nurse in Seattle.
© 2004 The Washington Post Company