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.
ANTIBIOTIC POLICIES
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.
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.
Related Topics
TH 2019 - 2023 pharmacy180.com; Developed by Therithal info.