Clinical Uses of Antimicrobial Drugs - Introduction

CLINICAL USES OF ANTIMICROBIAL DRUGS

INTRODUCTION

The worldwide use of antimicrobial drugs continues to rise; in 2005 these agents accounted for an expenditure of approximately £ 26 billion. In the UK, prescribing in general practice accounts for approximately 90% of all antibiotics and largely involves oral and topical agents. Hospital use accounts for the remaining 10% of antibiotic prescribing, with a much heavier use of injectable agents. Although this chapter is concerned with the clinical use of antimicrobial drugs, it should be remembered that these agents are also extensively used in veterinary practice and, to a diminishing extent, in animal husbandry as growth promoters. In humans the therapeutic use of anti-infectives has revolutionized the management of most bacterial infections, many parasitic and fungal diseases and, with the availability of aciclovir and a growing number of antiretroviral agents (see Chapters 5 and 11), selected herpesvirus infections and HIV infection, respectively. Although originally used for the treatment of established bacterial infections, antibiotics have proved useful in the prevention of infection in various high-risk circumstances; this applies especially to patients undergoing various surgical procedures where perioperative antibiotics have significantly reduced postoperative infectious complications.

The advantages of effective antimicrobial chemotherapy are self-evident, but this has led to a significant problem in ensuring that they are always appropriately used. Prescribers face a dilemma: initial antimicrobial therapy must be effective against all likely infective organisms for the individual presentation, but excessive use of broad-spectrum agents contributes to the development and selection of drug-resistant organisms. Hence, anti-infectives are the only class of drug where inappropriate use in one patient can jeopardize the efficacy of treatment in other individuals.

Examples of inappropriate antimicrobial use include prescribing in situations where antibiotics are either ineffective, such as viral infections, or where the selected agent, its dose, route of administration or duration of use are inappropriate. Of particular concern is the unnecessarily prolonged use of antibiotics for surgical prophylaxis. Apart from encouraging superinfection by drug-resistant organisms, prolonged use is wasteful of health resources and unnecessarily increases the risk of adverse drug reactions. Thus, it is essential that the clinical use of these agents be based on a clear understanding of the principles that have evolved to ensure safe, yet effective, prescribing.