Topping the most-wanted list: Drugs to fight the superbugs
■ Congress and the FDA can step in to provide incentives to drug firms for the development of new antimicrobials, says an infectious diseases group.
By Susan J. Landers — Posted Aug. 9, 2004
Washington -- Twelve-year-old Nicholas Johnson sprained his shoulder at football practice near his Stafford, Texas, home last fall. Three days later he was hospitalized with a life-threatening methicillin-resistant Staphylococcus aureus infection.
His story highlights the fact that MRSA can be a threat to young, healthy people, according to infectious diseases experts. An ongoing University of Texas study of children with community-acquired staph infections has found that nearly 70% were infected with a methicillin-resistant strain.
It also calls attention to the fact that drug-resistant bacteria continue to pose a major public health threat, particularly because there are very few new antibiotics now in development that can fight these deadly pathogens.
The number of antibacterial agents approved by the Food and Drug Administration dropped precipitously between 1983 and 2002, according to a study published in the May 1 issue of the journal Clinical Infectious Diseases. Since 1998, only 10 new antibiotics have been approved, and only two are novel agents that have a new target of action.
"There simply aren't enough new drugs in the pharmaceutical pipeline to keep pace with the evolution of drug-resistant bacteria, the so-called 'superbugs,' " said Joseph R. Dalovisio, MD, president of the Infectious Diseases Society of America at a July 21 Capitol Hill briefing.
"This crisis has the potential to touch us all because drug-resistant infections can strike anyone -- young or old, healthy or chronically ill," said Dr. Dalovisio, who heads the infectious diseases section of the Ochsner Clinic Foundation in New Orleans.
Steps needed to spur development
While good antibiotic stewardship, infection control and prevention efforts, increased surveillance and limits on agricultural uses of antibiotics are all important steps for limiting the impact of antibiotic resistance on patients, the development of effective antibiotics is becoming a more pressing need, according to "Bad Bugs, No Drugs," a report by the IDSA.
Pharmaceutical companies are not as likely to launch efforts to develop new antibiotics because they are not as profitable as other drugs. They work quickly and effectively and produce a weak return on investment dollars in contrast to drugs that patients take for life, such as insulin and statins.
"Market forces alone will not solve the antibiotic availability problem," said W. Michael Scheld, MD, immediate past president of IDSA and a professor of infectious diseases at the University of Virginia.
Congress can provide incentives similar to the extended market exclusivity offered by the Orphan Drug Act and the Best Pharmaceuticals for Children Act. Even the new BioShield law, created to encourage the development of vaccines and other countermeasures to biological terrorism agents, offers potential. Tax incentives and flexible statutory approval processes also could help encourage the development of antimicrobials, noted the IDSA report.
Meanwhile, experts are particularly concerned about the dearth of new "narrow-spectrum" agents. Broad-spectrum antibiotics, which are intended to work against a wide range of organisms, are more likely to contribute to development of resistance.
Not a rare example
Fortunately for Nicholas and his physicians, the available ammunitions were still effective in fighting back the infection that had spread to his bones, blood and lungs. Although he's still on antibiotics and has lost hearing in one ear, he was able to participate in baseball practice this past spring, said his mother.
But what happened to him is no longer an isolated occurrence. Since 2000, the Centers for Disease Control and Prevention has reported outbreaks of community-acquired MRSA among college football players in Pennsylvania, wrestlers in Indiana and a fencing club in Colorado. MRSA even broke out among the Miami Dolphins football team.
Public health officials believe that physical contact and the sharing of clothing or equipment probably leads to the spread of infection in these otherwise healthy people.
Bacteria are quickly evolving targets. Staph bacteria, for example, have acquired resistance to many drugs and are even partially resistant to vancomycin. Two cases of fully vancomycin-resistant S. aureus infection were reported in 2002 and a third in 2004, according to the report.
Streptococcus pneumoniae, which causes 6 million childhood ear infections each year, 3,300 cases of meningitis and thousands of cases of sinusitis as well as 100,000 cases of pneumonia, is also developing resistance. Up to 40% of infections caused by this bacterium are resistant to at least one drug, and 15% are resistant to three or more, according to the CDC.
In addition, Salmonella, which is the cause of many cases of foodborne illnesses, is developing resistance to cephalosporins, and tuberculosis is becoming increasingly difficult to treat.