Surveillance of Antibiotic Resistance: Learning to Live with Bias

Abstract

The introduction of antibacterial drug therapy in the 1940s led to a dramatic reduction in illness and death from infectious diseases over the next 50 years. Worldwide, antimicrobial drugs have saved the lives of hundreds of millions of people for whom premature death or crippling complications would have been unavoidable. However, the emergence of drug-resistant bacteria, fungi, and viruses is reversing the miracles of the previous 50 years. As we approach the 21st century, the choices of effective therapy for common infections will be more limited, much more expensive, or, in some cases, simply absent. We may be faced with the specter of hospital wards with patients dying of common, untreatable, infectious diseases. In recent years, a series of developments have highlighted the emergence of drug-resistant organisms. These include the following: * Once exquisitely susceptible to penicillin, drug-resistant Streptococcus pneumoniae infections have become common in some communities. S pneumoniae is the cause of at least 7,000,000 cases of middle ear infection in children, 500,000 cases of pneumonia, 50,000 cases of bacteremia, and 3,000 cases of meningitis; this pathogen causes at least 40,000 deaths per year in the United States. The proportion of strains with high levels of resistance to penicillin increased 60-fold between 1987 and 1992.1 In some regions of the United States, the proportion of strains resistant to penicillin is as high as 30%.2,3 * Antimicrobial resistance to penicillins and tetracyclines has emerged in Neisseria gonorrhoeae, the causative agent of gonorrhea, to the extent that expensive agents such as broad-spectrum cephalosporins and fluoroquinolones currently are recommended for the treatment of uncomplicated gonorrhea.4 * Hospital-acquired (nosocomial) infections aff ct approximately 2 million hospitalized patients in he United States, contributing to 80,000 deaths each y ar. Drug-resistant nosocomial pathogens are making some of these infections difficult (as with Staphylococcus aureus) or impossible (vancomycinresistant Enterococcus) to treat and are driving up costs of hospital care and mortality.5 * Foodborne diseases cause millions of illnesses each year in the United States. Periodic monitoring of Salmonella has shown a steady increase in the prevalence of antimicrobial resistance in this pathogen from 17% in 1980 to 31% in 1990.6 Epidemic dysentery due to Shigella dysenteriae type 1 is now a major threat in southern Africa.' This disease caused over 20,000 deaths 20 years ago in Latin America, where it could reemerge. Antimicrobial therapy for S dysenteriae can be life-saving, but widespread prevalence of drugresistant strains makes treatment expensive or imposs ble in some developing countries. This list could go on to discuss fungi, viruses, mycobacteria, and other microorganisms developing antimicrobial resistance. How do we know these