Antibiotics: Introduction
NB: See learning outcomes for this tutorial mapped to competencies and a PDF of the whole text, and a one-page summary.
☞ Why this subject matters...
Antibiotic resistance is a serious, global problem. Every decision you make about antibiotics matters not just for your patient but for everyone. You therefore need to be able to guide antibiotic prescribing with confidence, considering the patient, the causative organism and the site of infection.It’s a huge topic and this section cannot cover everything you will ever need to know, but it will give you a framework for reviewing an antibiotic prescription guide you how to tailor therapy to your individual patient and signpost you to current guidelines on commonly encountered infections.
Prescribing responsibly
Resistance occurs naturally over time, but inappropriate antibiotic use means that this problem has increased significantly over the last 40 years. That, together with fewer new antibiotics being developed, means quite simply that we may struggle to treat patients effectively in the future. It’s a worldwide issue but you have the potential to make a difference with every antibiotic prescription you review.
Assess
• Assess patient for clear evidence of infection – to establish whether the patient is likely to benefit from antimicrobials as unnecessary use can increase the risk of patient harm.
• Perform a comprehensive patient risk assessment to guide selection of proportionate treatment and determine the appropriate care environment. This should include considering disease severity, immunocompromised patients, likelihood of resistant pathogen, prior exposure to antimicrobials, and patients with factors commonly associated with health inequalities where appropriate.
Investigate
• Obtain appropriate specimens for culture prior to commencing therapy where possible, including blood cultures before starting antimicrobial treatment if appropriate (but do not delay treatment in cases of severe sepsis) – to guide targeting of treatment in the event of subsequent deterioration and to support de-escalation to narrow-spectrum treatment.
• Follow local guidelines for ordering appropriate laboratory investigations (biochemistry, haematology, immunology, organ function) and medical imaging where available.
• Implement any required source control interventions as soon as medically or surgically practical – to reduce the risk of treatment failure.
Prescribe
• Initiate prompt antimicrobial treatment for patients with severe sepsis or life-threatening infections based on local guidelines – to reduce avoidable morbidity and mortality.
• Comply with local antimicrobial prescribing guidance informed by local resistance patterns or national guidance (as appropriate) – to improve clinical outcomes for patients.
• Take a detailed drug allergy history, document and consider de-labelling allergies where appropriate – to ensure patients are not denied access to the most effective therapy.
• Avoid indiscriminate use of broad-spectrum antimicrobials – to preserve the effectiveness of these agents, reduce collateral damage to the patient’s microbiota and reduce the risk of opportunistic infection (such as C. difficile).
• For surgical prophylaxis: Prescribe single dose antimicrobials where single dose antimicrobials have been shown to be effective – to minimise post-operative surgical site infection at an acceptable risk of harm from antimicrobial exposure.
Document
• Document evidence of infection, working diagnosis (and disease severity), drug name, dose, formulation, and route on the prescription chart and in the clinical notes – in accordance with good clinical record-keeping.
• Consider using the ‘antibiotic review kit (ARK) decision aids’ to categorise prescribing for possible or probable infection – to facilitate subsequent review and refinement of the treatment plan.
• Include treatment duration where possible or specify a review date – to avoid unnecessarily prolonged treatment.
• Record a clear clinical plan for patient management – to ensure safe handover of care between clinical teams.
• If clinically essential to consider medical prophylaxis with antimicrobials, document clearly the indication and plan for review – to inform subsequent clinical decisions.
Then Focus - antimicrobial review:
• Review and revise the clinical diagnosis and the continuing need for antimicrobials at 48 to 72 hours* and document a clear plan of action from the antimicrobial review outcomes.
• The 5 antimicrobial review outcomes (CARES) are to:
1. Cease antimicrobial prescription if there is no evidence of infection – to reduce the risk of harm from antimicrobial treatment in the absence of benefit.
2. Amend antimicrobials – ideally to a narrower spectrum agent – or broader if required – to ensure that treatment is effective and proportionate.
3. Refer to non-ward based antimicrobial therapy services (such as ‘complex outpatient antimicrobial therapy’ – COPAT, or virtual wards) for appropriate patients if available – to facilitate timely discharge from hospital and reduce risk of acquisition of healthcare-associated infection.
4. Extend antimicrobial prescription and document next review date or stop date – to avoid inappropriately prolonged treatment.
5. Switch antimicrobials from intravenous to oral according to national intravenous to oral switch (IVOS) criteria – to facilitate timely discharge from hospital and reduce the risk of harm from intravenous administration.
It is essential that the review and subsequent decision is clearly documented in the clinical notes and on the drug chart where possible, for example ‘stop antimicrobial’. The antimicrobial review may encompass more than one of the outcomes depending on clinical circumstances.
*48 to 72 hours is the anticipated typical interval before ‘review and revise’ as results of diagnostic investigations are expected within 72 hours; however, factors such as rapid diagnostics and acute changes in clinical circumstances may facilitate or mandate earlier review and/or intervention.
Before choosing an antibiotic several factors need to be considered - the patient, the causative organism and the site of infection. The next few pages will guide you through the key considerations in making this decision.