As health care professionals, we need to look at our dispensing patterns to ensure that antibiotics are administered appropriately and that their use is based on an accurate diagnosis.
The discoveries of potent antimicrobial agents in the 1930s and 1940s were accompanied by optimistic predictions of being able to vanquish all threats from bacterial infections within a couple of decades. Despite the fact that resistances to most antibiotics were noted already within the first couple of years after their introduction into clinical medicine, there was no great concern, as a steady stream of novel antibiotics was produced continuously.
From the 1930s through the 1960s, 10 different classes, and numerous derivations, of antibiotics became available. Any suggestion that the "bugs could defeat the drugs" was crushed by the exuberance and confidence that the world soon would be purged of bacterial and other infectious diseases. This optimism was shared by the pharmaceutical industry, which started to divert its efforts and resources into research and production of other types of medications. Consequently, no new classes of antibiotics were introduced during the 1970s, 1980s and 1990s. Since 2000, only a couple of new antibiotics have been put on the market, but the question is whether this is too little too late, as startling rates of bacterial resistance to antibiotics has emerged as a serious threat to public health.
It has been estimated that in 1992, more than 13,000 deaths in health care settings could be attributed to antimicrobial resistance. By 2004, this number may have reached 90,000. A report from 2003 projected that 5 to 10 percent of all patients admitted to a hospital in the United States would acquire at least one nosocomial infection.1 However, an even larger threat to public health is the rapidly increasing drug resistance noted in the community. Recent data suggest that up to 27,000 residents of nursing homes have antibiotic-resistant infections.2
The classic example to illustrate the development of bacterial resistance is the story of Staphylococcus aureus. Before the use of penicillin, the mortality rates associated with S. aureus bacteremias were above 80 percent. With the introduction of penicillin in the 1940s, the survival rate increased to an astonishing 98 percent. However, penicillinase-producing strains soon developed. Fortunately, other antibiotics such as methicillin, a penicillinase-stable ß-lactam agent, became available. (ß-lactamase is an enzyme produced by bacteria to prevent the actions of penicillins and cephalosporins.) Regrettably, with the increased use of methicillin, strains of methicillin-resistant Staphylococcus aureus (MRSA) emerged among hospitalized patients.
Today, it is estimated that 60 percent of all hospital-acquired S. aureus infections are MRSA strains. Although most MRSA infections initially were confined to hospitals and other health care institutions, in recent years community-acquired MRSA has surfaced as a significant problem. This type of MRSA is not limited to traditionally susceptible patient populations, such as people with compromised immune systems, patients undergoing renal dialysis, oncology patients and elderly people. Instead, MRSA is infecting all strata of the population.
Severe soft-tissue infections caused by MRSA have been documented among healthy young athletes such as football players, wrestlers and even fencers. A recent study even documented a significant problem with MRSA among professional football players.3 Vancomycin has been used sparingly to save this agent for cases in which no other antibiotic has been successful in combating resistant infections. Soon van-comycin-intermediate S. aureus strains emerged, followed by a critical and devastating hospital-acquired vancomycin-resistant S. aureus (VRSA) strain. In 2002, two cases of community-acquired VRSA infections were documented in the United States. Thus, in less than 70 years, the treatment of S. aureus infection has almost come full circle.
Antimicrobial resistance by ß-lactamase is growing through extended-spectrum ß-lactamases and metallo-ß-lactamases (MBL) producing bacteria. Resistance to MBL is particularly troublesome as it affects carbapenems, a type of antibiotic usually looked on as the last resort for many different infections. Drug resistance is not limited to bacterial infections. Significant resistance exists to antiretroviral medications, as well as to antiparasitic medications used to treat diseases such as malaria.
Microbial pathogens have the capability to alter their genetic structure, possibly allowing them to resist all forms of antimicrobial medications. Bacteria can acquire resistance by altering the binding site for the antibiotic, by forming a lower binding affinity, or by changing the degradative systems or clearing of the antibiotic from the cell. The bacteria are highly adaptable and can transfer resistance genes to other bacteria populations and confer resistance to other antibiotics.
Excessive use of antibiotics often is blamed for the emergence of resistance. Yet, only a causal link exists between antibiotic resistance and antibiotic consumption. The widespread resistance in hospitals instead may be due to close proximity of patients with compromised immune systems and a lack of good infection control, the unnecessary use of broad-spectrum antibiotics, use of an antibiotic for too long a duration, and little attention to the use of the most appropriate antibiotic. Poor patient compliance also is a main reason for the emergence of multidrug-resistant (MDR) bacteria, as has been documented in cases of MDR-tuberculosis (MDR-TB). When patient compliance is monitored, the rate of MDR-TB decreases dramatically.
Another major cause of drug resistance is the practice of adding antibiotics to animal feed to promote growth. This permits resistant bacteria to survive and make their way into meat and, consequently, into humans. Studies in Europe have shown that discontinuing this practice can reduce the development of resistant bacteria substantially.
Microbial drug resistance is associated with dire consequences. It directly affects morbidity and mortality, causes considerable increases in health care spending, and reduces the number of available drugs for future patients. All providers who dispense antibiotics, including dentists, urgently need to address this public health problem.4,5
As health care professionals, we need to look at our dispensing patterns to ensure that antibiotics are administered appropriately and that their use is based on an accurate diagnosis.4,5 Joint efforts between organized dentistry and public health officials through education of professionals and the public may be an important beginning to address this problem.
