Antibiotic Policies

ANTIBIOTIC POLICIES   

RATIONALE

The plethora of available antimicrobial agents presents both an increasing problem of selection to the prescriber and difficulties for the diagnostic laboratory as to which agents should be tested for susceptibility. Differences in antimicrobial activity among related compounds are often of minor importance but can occasionally be of greater significance and may be a source of confusion to the non-specialist. This applies particularly to large classes of drugs, such as the penicillins and cephalosporins, where there has been an explosion in the availability of new agents in recent years. Guidance, in the form of an antibiotic policy, has a major role to play in providing the prescriber with a range of agents appropriate to his/her needs and should be supported by laboratory evidence of susceptibility to these agents.

In recent years, increased awareness of the cost of medical care has led to a major review of various aspects of health costs. The pharmacy budget has often attracted attention as, unlike many other hospital expenses, it is readily identifiable in terms of cost and prescriber. Thus, an antibiotic policy is also seen as a means whereby the economic burden of drug prescribing can be reduced or contained. There can be little argument with the recommendation that the cheaper of two compounds should be selected where agents are similar in terms of efficacy and adverse reactions. Likewise, generic substitution is also desirable provided that there is bio-equivalence. It has become increasingly impractical for pharmacists to stock all the formulations of every antibiotic currently available, and here again an antibiotic policy can produce significant savings by limiting the amount of stock held. A policy based on a restricted number of agents also enables price reduction on purchasing costs through competitive tendering. The above activities have had a major influence on containing or reducing drug costs, although these savings have often been lost as new and often expensive preparations become available, particularly in the field of biological and anticancer therapy.

Another increasingly important argument in favour of an antibiotic policy is the occurrence of drug-resistant bacteria within an institution. The presence of sick patients and the opportunities for the spread of microorganisms can produce outbreaks of hospital infection.

The excessive use of selected agents has been associated with the emergence of drug-resistant bacteria which have often caused serious problems within high-dependency areas, such as intensive care units or burns units where antibiotic use is often high. One oft-quoted example is the occurrence of a multiple antibiotic-resistant K. aerogenes within a neurosurgical intensive care unit in which the organism became resistant to all currently available antibiotics and was associated with the widespread use of ampicillin. By prohibiting the use of all antibiotics, and in particular ampicillin, the resistant organism rapidly disappeared and the problem was resolved.

Currently the most important hospital-acquired pathogen is methicillin-resistant Staph. aureus, which is responsible for a range of serious infections such as pneumonia, postoperative wound infection and skin infections which may in turn be complicated by bloodstream spread. The use of vancomycin and teicoplanin has escalated as a consequence, and in turn has been linked to the emergence of vancomycin-resistant enterococci. Likewise, the increased prevalence of ESBL-producing Gramnegative pathogens in intensive care settings often leads to increased usage of carbapenems, and a corresponding rise in carbapenem-resistant Klebsiella and Pseudomonas species on these units.

In formulating an antibiotic policy, it is important that the susceptibility of microorganisms be monitored and reviewed at regular intervals. This applies not only to the hospital as a whole, but to specific high-dependency units in particular. Likewise general practitioner samples should also be monitored. This will provide accurate information on drug susceptibility to guide the prescriber as to the most effective agent.

TYPES OF ANTIBIOTIC POLICIES

There are a number of different approaches to the organization of an antibiotic policy. These range from a deliberate absence of any restriction on prescribing to a strict policy whereby all anti-infective agents must have expert approval before they are administered. Restrictive policies vary according to whether they are mainly laboratory controlled, by employing restrictive reporting, or whether they are mainly pharmacy-controlled, by restrictive dispensing. In many institutions it is common practice to combine the two approaches.

a)  Free Prescribing

The advocates of a free prescribing policy argue that strict antibiotic policies are both impractical and limit clinical freedom to prescribe. It is also argued that the greater the number of agents in use the less likely it is that drug resistance will emerge to any one agent or class of agents. However, few would support such an approach, which is generally an argument for mayhem.

b)  Restricted Reporting

Another approach that is widely practised in the UK is that of restricted reporting. The laboratory, largely for practical reasons, tests only a limited range of agents against bacterial isolates. The agents may be selected primarily by microbiological staff or following consultation with their clinical colleagues. The antibiotics tested will vary according to the site of infection, as drugs used to treat urinary tract infections often differ from those used to treat systemic disease.

There are specific problems regarding the testing of certain agents such as the cephalosporins, where the many different preparations have varying activity against bacteria. The practice of testing a single agent to represent first-generation, second-generation or third-generation compounds is questionable, and with the new compounds susceptibility should be tested specifically to that agent. By selecting a limited range of compounds for use, sensitivity testing becomes a practical consideration and allows the clinician to use such agents with greater confidence.

c)   Restricted Dispensing

As mentioned above, the most draconian of all antibiotic policies is the absolute restriction of drug dispensing pending expert approval. The expert opinion may be provided by either a microbiologist or infectious disease specialist. Such a system can only be effective in large institutions where staff are available 24 hours a day. This approach is often cumbersome, generates hostility and does not necessarily create the best educational forum for learning effective antibiotic prescribing.

A more widely used approach is to divide agents into those approved for unrestricted use and those for restricted use. Agents on the unrestricted list are appropriate for the majority of common clinical situations. The restricted list may include agents where microbiological sensitivity information is essential, such as for vancomycin and certain aminoglycosides. In addition, agents that are used infrequently but for specific indications, such as parenteral amphotericin B, are also restricted in use.

Other compounds that may be expensive and used for specific indications, such as broad-spectrum β-lactams in the treatment of Ps. aeruginosa infections, may also be justifiably included on the restricted list. Items omitted from the restricted or unrestricted list are generally not stocked, although they can be obtained at short notice as necessary.

Such a policy should have a mechanism whereby desirable new agents are added as they become available and is most appropriately decided at a therapeutics committee. Policing such a policy is best effected as a joint arrangement between senior pharmacists and microbiologists. This combined approach of both restricted reporting and restricted prescribing is extremely effective and provides a powerful educational tool for medical staff and students faced with learning the complexities of modern antibiotic prescribing.

d)   The Antimicrobial Stewardship Team

In an attempt to ensure antimicrobials are prescribed appropriately in hospitals, antimicrobial stewardship teams have emerged to advise and educate staff while monitoring compliance with prescribing policies as well as ensuring good standards of patient management. Typically these teams comprise, at their core, a consultant in infectious diseases and/or clinical microbiology, and a senior pharmacist specializing in infectious diseases, and may also include infection control practitioners. The team takes a lead in reviewing the therapy of individual patients and setting treatment plans, and, often as part of a wider team, will coordinate the writing and review of antibiotic treatment policies. Other responsibilities may include the education and training of clinical staff, the audit of how well prescribers are adhering to the carefully written policies, and the provision of feedback to prescribers. Evidence suggests that this multidisciplinary approach, aligned with targeted and timely feedback, can improve adherence to prescribing policy, reduce drug expenditure, and improve patient outcomes.