Antibiotic guidelines - Introduction

Introduction

Antimicrobial Prescribing Tips (Mala Shah CUH)

LRTIs:

• Piperacillin-tazobactam should not be used for the empiric treatment of community acquired pneumonia.
• Ciprofloxacin should not be used to treat community acquired LRTIs, and should not be used as a sole agent for empiric treatment of hospital acquired LRTIs as it has poor activity against S. pneumoniae.

UTIs:

• Ciprofloxacin and trimethoprim should not be used for empiric treatment (resistance).

Warfarin drug interactions:

• INR must be closely monitored and warfarin doses adjusted for antimicrobials, particularly macrolides (Clarithromycin*, Erythromycin).

Monitoring levels:

• Gentamicin, Vancomycin, tobramycin, streptomycin and amikacin levels must be monitored appropriately and where possible. resistance.

Vancomycin Loading Dose

All patients should receive a Vancomycin Loading Dose (hover for details) then 15mg/kg maintenance (assuming normal renal function).

Teicoplanin:

• Should be dosed according to patient weight.
• A standard dose is 6mg/kg (round up to the nearest 200mg): Seek advice. Don’t forget the loading dose (q12h for first 3 doses, then q24h thereafter).

IV to PO switch:

• Use oral treatment where possible for: ciprofloxacin, metronidazole, Clarithromycin*, Moxifloxacin **, Linezolid, Fluconazole, Rifampicin, Clindamycin.

Reviewing treatment:

• Always document indication for antimicrobial and proposed duration of treatment.
• Always review cultures daily
• Seek advice if unsure
• Review need for antimicrobial therapy daily. Prolonged therapy can lead to resistance and serious adverse effects, e.g. C. difficile.
• Respect the restricted access policy.
• If in doubt, always seek advice!
• Microbiology: extension 22504 / 22694
• Infectious Diseases SpR: bleep 203
• Antimicrobial Pharmacist: bleep 479
• Pharmacy: extension 22146 / 22542

* Clarithromycin can cause significant ↑↑ in INR. For patients on Warfarin and Clarithromycin*, INR must be monitored very closely.

Before starting antibiotics

• The decision to prescribe an antibiotic must be based on clinical evidence of infection. Establish a provisional diagnosis. This will give an indication of the most likely causative organisms, and the most suitable empiric treatment.
• If possible, take samples (especially blood cultures) for culture and sensitivity testing before starting antibiotics. In certain circumstances, e.g. suspected bacterial meningitis, antibiotics should be given immediately. In patients with life threatening infections, do not delay empirical therapy whilst awaiting microbiology results.
• Consider the patient’s medical history when deciding on treatment options: check allergy status, renal and hepatic function, pregnancy or breast feeding and concomitant medication. Refer to the BNF for drug – drug interactions.
• If there has been a history of anaphylaxis with penicillin avoid the following antibiotics: all ß-lactam antibiotics (e.g. penicillin, flucloxacillin, amoxicillin, ampicillin, co-amoxiclav, piperacillin-tazobactam, meropenem) and cephalosporins.
• There is a 10% cross- sensitivity with cephalosporins in penicillin allergy and they may be trialled in patients with a penicillin allergy that was not severe, e.g. mild rash only. Ensure allergy box is completed on the drug charts and cover of notes.
• Take account of recent culture reports as empiric treatment may require modification as a result: e.g. recent MRSA culture.
  • Recent antibiotic use - consider use of an antibiotic from a different class, if suitable.
• Always document the reason why an antibiotic is commenced, and the proposed duration of treatment.
• Take appropriate samples. Refer to the Laboratory Users Manual.
• A microbiology result should not be examined in isolation: treat the patient, not the result. The sensitivity profile on the report is not necessarily a recommendation to treat with antibiotics, as organisms of no clinical significance may grow from non-sterile sites (colonisation).

Reviewing antibiotic treatment

• Review need and choice of antibiotic daily
• When sensitivities are known, change to the narrowest spectrum agent to which the culture is sensitive. If in doubt, seek advice.
• Route of administration – see Appendix 1 for iv to oral switch policy.
• Duration of treatment: in general, most antibiotic courses need not exceed 5-7 days. Unnecessarily prolonged courses may result in unwanted side effects (e.g. pseudomembranous colitis) and may contribute to the selection of resistant organisms, e.g. MRSA and VRE. Some infections will require a longer duration of treatment: e.g. endocarditis, severe pneumonia and bone and joint infections.
• Antibiotic level monitoring: some antibiotics need levels monitored to avoid toxicity. These include Vancomycin Loading Dose (hover) then, gentamicin, tobramycin, amikacin and streptomycin. Please see Appendices 2 (Aminoglycosides) and 3 (Vancomycin) for details.

Resistance

The development of antimicrobials is generally accepted as the most significant medical development of the last century. In addition to saving thousands of lives, antimicrobials have enabled advances such as the use of cytotoxic chemotherapy, the use of immunosuppressive drugs, transplantation and other types of surgery. The problem of antimicrobial resistance (AMR), however has been recognised since the introduction of penicillin into clinical practice in the 1940s. In the past, the development of new agents partially compensated for this problem. However, over the last 15 years the prevalence of AMR has continued to escalate and the number of new classes of antibacterial drug marketed has been extremely limited.

AMR is now accepted as a major public health threat and is associated with excess morbidity and mortality, prolongation of hospital stay and epidemics of infection, and increased antibiotic costs.

The prevention of spread of antimicrobial resistance focuses on two main strategies: ensuring the appropriate use of antimicrobials and good hygiene.

When agreeing local guidelines in relation to antimicrobial use it is important to consider local variations in resistance rates. These guidelines have been developed taking into account locally available data.

Exposure to antibiotics increases the rate of emergence of resistant strains. Therefore it is important to use antibiotics only when clinically indicated, for the shortest effective duration and using an appropriate dose. Resistant organisms are especially important in a hospital setting and outbreaks of cross infection may be facilitated by inappropriate use of antibiotics. Because of this, some antibiotics are restricted and usually only prescribed after specialist advice.

Prescribers will be advised to seek specialist advice as outlined below before these antimicrobials are dispensed by the Pharmacy Department.

Restricted Antimicrobials

Exposure to antibiotics increases the rate of emergence of resistant strains. Therefore it is important to use antibiotics only when clinically indicated, for the shortest effective duration and using an appropriate dose. Resistant organisms are especially important in a hospital setting and outbreaks of cross infection may be facilitated by inappropriate use of antibiotics. Because of this, some antibiotics are restricted and usually only prescribed after specialist advice.

Prescribers will be advised to seek specialist advice as outlined below before these antimicrobials are dispensed by the Pharmacy Department.

Restricted Antimicrobials

Antimicrobial	Restricted to:
Meropenem	Microbiology / Infectious Diseases / Respiratory Consultant only
Ceftazidime	Microbiology / Infectious Diseases / Respiratory Consultant only
Linezolid	Microbiology / Infectious Diseases / Respiratory Consultant only
Aztreonam	Microbiology / Infectious Diseases / Respiratory Consultant only
Daptomycin	Microbiology / Infectious Diseases only
Tigecycline	Microbiology / Infectious Diseases only
Ambisome® (liposomal amphotericin)	Microbiology / Infectious Diseases / Haematology Consultant only
Caspofungin	Microbiology / Infectious Diseases / Haematology Consultant only
Voriconazole	Microbiology / Infectious Diseases only
Posaconazole	Microbiology / Infectious Diseases only

The following antibiotics are not used at CUH, in adults.

• Imipenem (alternative: meropenem)
• Cefotaxime (alternative: ceftriaxone. Cefotaxime reserved for use in neonates and children)
• Ampicillin (alternative: amoxicillin)
• Oral cephalosporins (except oral cefalexin for treatment of urinary tract infection).
• Oral cefuroxime (poor bioavailability, so reserved for treatment of UTI sensitive only to cefuroxime. Use co-amoxiclav if an oral step-down needed from iv cefuroxime, seek advice in penicillin allergy)
• Oral penicillin (alternative: oral amoxicillin, as penicillin has poor bioavailability. Exception: patients on long-term oral penicillin post splenectomy)

Appendices

• Appendix 1 Switching from IV to PO therapy
• Appendix 2 Aminoglycoside monitoring
• Appendix 3 Vancomycin
• Appendix 4 Clostridium difficile diarrhoea
• Appendix 5 MRSA
• Appendix 6 Renal impairment, antibiotics
• Appendix 7 IV preparations
• Appendix 8 Prescribing Tips
• Prophylaxis - Endocarditis
• Prophylaxis - Meningitis
• Prophylaxis - Post Splenectomy /Hyposplenic
• Penicillin Allergy
• SEPSIS.

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