Antimicrobial Therapy and Stewardship
Antimicrobial therapy is the use of agents that kill or inhibit infecting microorganisms—bacteria, viruses, and fungi—while sparing the human host. This area orients the reader to the major drug classes, the mechanisms by which microbes resist them, and the discipline of stewardship that aims to preserve the effectiveness of these agents for future patients.
Definition
Anti-infective agents are drugs used to treat infections by destroying or suppressing the growth of microorganisms; the term spans antibacterial, antiviral, and antifungal agents, and the area also encompasses the resistance these agents select for and the stewardship practices meant to slow it.
Scope
The area groups the foundational topics of anti-infective pharmacology: the principal antibiotic, antiviral, and antifungal drug classes and how they act; the biological and ecological basis of antimicrobial resistance; and antimicrobial stewardship as a coordinated effort to optimise the use of these agents. It is a reference and educational orientation, not a prescribing resource.
Sub-topics
Core questions
- What are the major classes of antibacterial, antiviral, and antifungal agents and how do they act selectively on microbes?
- How do microorganisms acquire and spread resistance to antimicrobial agents?
- What is selective toxicity and why is it harder to achieve for viruses and fungi than for bacteria?
- How does antimicrobial stewardship try to balance effective treatment of the individual with preservation of these drugs for the population?
Key concepts
- Selective toxicity
- Mechanism of action by drug class
- Bactericidal versus bacteriostatic activity
- Spectrum of activity
- Antimicrobial resistance and selection pressure
- Antimicrobial stewardship
Mechanisms
Antimicrobial agents exploit differences between microbial and human cells—for example bacterial cell-wall synthesis, microbial ribosomes, viral enzymes, or the fungal cell membrane and wall—to achieve selective toxicity. The breadth of organisms an agent affects defines its spectrum, and agents may kill organisms (bactericidal) or merely halt their growth (bacteriostatic). Because every exposure selects for less-susceptible organisms, the use of these agents is inseparable from the emergence of resistance, which is the conceptual link between the pharmacology topics and the stewardship topic in this area.
Clinical relevance
Anti-infective agents are among the most widely used drugs in medicine, and understanding how they work, how resistance arises, and why their use must be stewarded is foundational to the health sciences. This area describes the principles that underlie rational antimicrobial use at a conceptual level; it is not a source of dosing or individualised treatment decisions, which depend on the specific organism, infection, and patient and are governed by current clinical guidelines.
Epidemiology
Antimicrobial resistance is recognised globally as a major and growing threat to public health, with broad reviews documenting its drivers across human medicine, agriculture, and the environment and calling for coordinated international action. The scale of the problem motivates stewardship programmes in hospitals and communities worldwide.
Evidence & guidelines
Professional societies publish practice guidelines for antimicrobial stewardship and for the management of specific infections; the IDSA/SHEA stewardship guideline is a widely cited example. These guidelines are voluntary recommendations that cannot account for every individual patient and are periodically updated.
History
The modern era of antimicrobial therapy began with the sulphonamides and with penicillin in the first half of the twentieth century, followed by successive generations of antibacterial, antiviral, and antifungal agents. The recognition that resistance follows closely behind each new agent gave rise, in recent decades, to the formal discipline of antimicrobial stewardship.
Related topics
Seminal works
- laxminarayan-2013
- holmes-2016
- barlam-2016
Frequently asked questions
- What does 'anti-infective' cover?
- It is an umbrella term for agents used against infectious organisms, including antibacterial (antibiotic), antiviral, and antifungal drugs; antiparasitic agents are sometimes included as well.
- Why is antimicrobial stewardship part of this area?
- Because every use of an antimicrobial agent selects for resistance, optimising how these drugs are used is inseparable from understanding the drugs themselves; stewardship is the practice that links individual treatment to the long-term preservation of the agents.