Practical Antibiotic Prescribing & Antibiotic Awareness Berny Baretto (Antibiotic Pharmacist) 21st November 2013

Contents Antibiotic Awareness Day-18 th November 2013 How to prescribe an antibiotic Why is it important? Background Audit What must be included in an antibiotic prescription Practical examples Gentamicin Prescribing Summary

European Antibiotic Awareness Day- campaign to promote prudent antibiotic use(supported by DOH)

European Antibiotic Awareness Day 18 November 2013

Key Messages It is a public health initiative aimed at encouraging responsible use of antibiotics Lack of new antibiotics being developed especially to cover gram negative bacteria. Number of infections due to antibiotic–resistant bacteria is growing Important to preserve the use of the antibiotics currently available eg carbapenems

Background contd-Use selects Resistance Acquired resistance absent from bacteria collected pre Resistance repeatedly followed introduction of new antibiotics Resistance greatest where use heaviest Resistant mutants selected in therapy

Β-Lactam use & resistance in S.pneumoniae Bronzwaer et al Emerg Infect Dis. 2002; 8: Low rates of antibiotic use = low resistance →

How to prescribe an antibiotic –why is it important Department of Health Guidelines-(Advisory Committee on antimicrobial resistance and healthcare associated Infection)-Nov 2011 Antimicrobial stewardship- “start smart-then focus”- Want : Right Drug Right Dose Right Time Right Duration For Every Patient

Start Smart Is : Don’t start antibiotics in the absence of clinical evidence of bacterial infection If there is evidence or suspicion of bacterial infection- use local antibiotic guidelines to start treatment Document on drug chart Indication, duration/review date, route & dose Obtain cultures first Prescribe single dose antibiotics for surgical prophylaxis-where proven efficacy

Then Focus is: Review clinical diagnosis and the coninuing need for antibiotics by 48 hours and make a clear plan of action- “the antimicrobial prescribing decision” 5 options 1. STOP 2. Switch i/v to oral 3. Change –ideally to narrower spectrum or broad if needed 4. Continue (review again at 72 hours) 5. Outpatient Parenteral antibiotics therapy (OPAT) Make sure review and decision is clearly documented in medical notes.

Department of Health Guidance-Antibiotic Stewardship

Good Prescribing Practice Promotes Good Prescribing Practice- no missed doses, ensures continuity in care Adherence to Trust Antibiotic Policy Helps to Reduce Incidence of Clostridium difficile Infection Audit

Quarterly Audit-(overall Trust Data) General Antibiotic Data Sep-12Dec-12Apr-13July-13 % Patients on antibiotics 30%32%34%32% % IV Antibiotics 56%51%47%63% % Oral Antibiotics 44%49%53%37%

Specific Antibiotic Monitoring Sep-12Dec-12Apr-13Jul-13 %i/v >48hrs 47%58%55%46% %>5days but ≤ 7 days 13%7%11%6% % > 7 day course 12%15%18%15% % > 7 day course appropriate 80%98%97%100% % Patients with allergy status documented 86% % Indication stated 67%64%69%71% % antibiotics prescribed appropriately when indication stated 98%95%96%99% % course length or review stated 50%58%51%53%

PRACTICAL EXAMPLES

What must be included in an antibiotic prescription-Documentation of allergy status

UTI Recommendation

Uncomplicated Cystitis

Crossing off an Antibiotic

Re-prescribing after antibiotic sensitivities appear on CRRS

Chest Infection Recommendation

Query Non-severe CAP

Gentamicin Prescribing 5 steps for safe gentamicin prescribing Usually gentamicin is only required for 24-48hrs. Course lengths for gentamicin should not exceed 5 days unless Microbiology have approved its use for extended durations (this may be indicated in some infections eg Endocarditis).

1. Weigh Patient: Weigh patient. If weighing is not possible, estimate weight using ideal body weight formulae (based on height and gender). For obese patients >120% ideal body weight use formula for dosing weight.-see below.

Equations for Ideal Body weight and Obese dosing Imperial Ideal Body weight (Male) = 50 + (2.3 x inches over 5 feet) Ideal Body weight (Female) = (2.3 x inches over 5 feet) Or Metric Ideal Body weight (Male) = 50kg + 0.9kg for each cm above 150cm in height Ideal Body weight (Female) = 45.5Kg + 0.9kg for each cm above 150cm in height For Obese Patients (> 120% of ideal body weight) use obese dosing weight calculation5 : Obese Dosing Weight (in Kg) = ideal body weight (actual Body weight – ideal body weight)

2. Calculate gentamicin Dose : Calculate the gentamicin dose using 5mg/Kg (maximum 400mg od) a)If normal body weight - use actual body weight value b)If Obese (> 120% of ideal body weight)- use obese dosing weight c) if weight unobtainable – calculate ideal body weight

3. Calculate creatinine clearance (CrCl) : Calculate the creatinine clearance using Cockcroft and Gault equation Creatinine = (140-age in years) x weight in Kg(from step 1) x F clearanceSerum Creatinine (in micromole/Litre) F=1.04 (female) or F=1.23 (male)

4. Check dosing Interval and when levels need to be done : Creatinine Clearance Dose IntervalPre-dose level check > 60ml/min24 hourlyBefore 2 nd /3 rd dose 41-60ml/min36 hourlyBefore 2 nd /3 rd dose 21-40ml/min48 hourlyBefore 2 nd dose < 21ml/min> 48 hourlyCheck level after 48 hours Work out the dosing interval and when levels should be checked

5. Check gentamicin serum level If pre-dose gentamicin level is 1mg/L or less continue the original dosing regime If pre-dose gentamicin level is greater than 1mg/L, consult Microbiology or Pharmacy for advice.

Documentation on Medicine Chart

SUMMARY 1. Antibiotic Awareness 2. What to include when prescribing an antibiotic- practical examples 3. Why do we document this- The background 4. Audit 5. Gentamicin prescribing