Management of infectious diseases

FEW AREAS OF MEDICINE have undergone greater change during the past 50 years than infectious diseases. The optimism and clinical confidence associated with the development of antimicrobial agents from the 1940s onwards has been tempered by the emergence of new diseases, such as AIDS and infections associated with transplantation and cancer therapy, and by the widespread development of antibiotic resistance. Despite many advances, infectious diseases continue to account for about a quarter of all deaths worldwide (Box 1). Furthermore, a security dimension has emerged. A recent report on The global infectious disease threat and its implications for the United States from the US Central Intelligence Agency (CIA) analysed this “non-traditional threat”: The dramatic increase in drug-resistant microbes, combined with the lag in development of new antibiotics, the rise of megacities with severe health care deficiencies, environmental degradation, and the growing ease and frequency of cross-border movements of people and produce have greatly facilitated the spread of infectious diseases. Clinicians today require more knowledge of infectious diseases than ever before. In this issue of the Journal (page 229), we begin MJA Practice Essentials — Infectious Diseases. This series cannot hope to cover all new aspects of infectious disease. Instead, we aim to discuss clinically important areas where recent advances have occurred in diagnosis or treatment, new diseases have been identified, or healthcare changes have necessitated new clinical approaches to “old” diseases (eg, endocarditis and cellulitis) (Box 2). Some important topics, such as HIV infection and bioterrorism, are beyond the scope of this series. Wherever possible, recommendations are evidence-based, with the evidence graded according to the system of the National Health and Medical Research Council3 (Box 3). As with much of medicine, management of infectious diseases is affected by the competing needs for prompt empirical treatment and for a definite diagnosis to allow focused therapy. Advances in diagnostic technology have enhanced the possibilities for rapid, accurate diagnosis of conditions such as sexually transmitted diseases, deepseated infections such as endocarditis and osteomyelitis, and common viral infections. However, identification of bacterial pathogens and their antibiotic susceptibilities still requires careful specimen collection and slow, generally labour-intensive, microbiological culture methods. Furthermore, many rapid diagnostic tests are sufficiently expensive that initial empirical “shot-gun” therapy without investigation can seem attractive. As effective antiviral agents become ever more readily available, many of the issues faced with antibiotics, such as rapid diagnosis, susceptibility testing and dosage monitoring, must also be considered. Current administrative pressure for shorter hospital stays and fewer outpatient or general practitioner consultations appears to encourage use of broad-spectrum empirical antibiotic and antiviral therapy, rather than careful investigation, review and directed therapy. Combined with the community’s apparent ready acceptance or expectation of antibiotic therapy, this may explain Australia’s ranking as the world’s second-largest per-capita consumer of antibiotics (after France).5-7 Similarly, in the US and Canada, it is estimated that about 50% of all outpatient prescriptions for antibiotics are unnecessary.7,8 Antibiotic resistance is now emerging as a key challenge to many healthcare programs. Indeed, developments such as multidrug-resistant tuberculosis and resistance among common pathogens in developManagement of infectious diseases