Antibiotics

James talks to Dr Rebecca Davis about the use of antibiotics to prevent or treat infections on the wards.

Summary Writer:  Duncan Campbell

Script Writer:. Duncan Campbell

Editor:  James Edwards

Interviewee:  Rebecca Davis

About Dr Rebecca Davis

Rebecca is a Staff Specialist in Infectious Diseases and Microbiology at Royal Prince Alfred Hospital. She has an interest in infections in immunocompromised patients and has been involved in teaching about rational use of antibiotics over many years.

Antibiotics

With Dr Rebecca Davis, Infectious Diseases and Microbiology Consultant at Royal Prince Alfred Hospital, New South Wales, Australia.

Antibiotics are typically prescribed in one of two different scenarios:

  • To prevent infection.
  • To treat suspected or confirmed infection.
  • Individuals may suffer side effects.
  • Antibiotic use will affect an individual’s future bacterial flora, and may increase their risk of infection with multi-resistant organisms or clostridium difficile.
  • Antibiotic use will affect others in the community, and may increase their risk of infection with multi-resistant organisms.
  • The use of broad-spectrum antibiotics is more likely to lead to antibiotic resistance than the use of targeted narrow-spectrum antibiotics.

To prevent infection, prophylactic antibiotics should target the most likely micro-organisms that pose risk to the patient, and for the shortest duration possible.

To treat suspected or confirmed infection, you should first try to find a focus (e.g. respiratory, urinary) and consider the severity of infection.

  • If the infection is mild to moderate, you have time to confirm the source of infection, and to consider if it is more likely to be bacterial or viral.
  • In the setting of severe sepsis, treatment should be commenced early, with broad spectrum intravenous antibiotics that will act quickly.
  • Have they have been colonised with specific bacteria in the past, e.g. MRSA, pseudomonas?
  • What were these bacteria sensitive to?
  • Do they have any allergies?
    • How severe is the allergy?
    • If anaphylaxis to penicillin, avoid penicillins and cephalosporins.
  • Consider co-morbidities, age, renal function, pregnancy and other medications that may interact.
  • Vancomycin:
    • Aim for a trough level of 15-20.
    • In an individual with normal renal function and standard BD dosing:
      • Check the trough level just before the 4th dose.
      • Adjust the 5th dose.
      • E.g. If level is 25, reduce the 5th dosage by ~25% i.e. 1 gram BD to 750 mg BD.
    • If there is an acute deterioration in creatinine clearance, check the level earlier!
  • Gentamicin:
    • Toxicity is more closely related to duration of use rather than dosage.
    • For initial dosage, consider renal function and age and refer to eTG.
    • In otherwise healthy and young individuals, consider 6 mg/kg.
    • In older and sicker individuals, consider 4-5 mg/kg.
    • Generally used short-term e.g. 2-3 doses (at one dose per day).
    • If only used for 2-3 doses, no need for level.
    • If >3 doses, check trough level before 3rd dose and adjust 4th dosage.

 

  • Electronic Therapeutic Guidelines.
  • Infectious diseases physicians and microbiologists on call.

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Tags: #Antibiotics,#gentamicin,#infection,#infectious disease,#Penicillins,#prescribing,#prophylactic,#prophylaxis,#side effects,#vancomycin

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