Louis Roller takes a look at the threat of antibiotic resistance

“…this serious threat is no longer a prediction for the future; it is happening right now in every region of the world and has the potential to affect anyone, of any age, in any country.”  World Health Organisation, 2014

Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic, while a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs.

Genes that confer resistance can be transferred between bacteria in a horizontal fashion by conjugation, transduction, or transformation. Thus, a gene for antibiotic resistance that evolves via natural selection may be shared.

Evolutionary stress such as exposure to antibiotics then selects for the antibiotic-resistant trait.

Many antibiotic resistance genes reside on plasmids, facilitating their transfer. If a bacterium carries several resistance genes, it is called multidrug resistant (MDR) or, informally, a superbug or super bacterium. Genes for resistance to antibiotics, like the antibiotics themselves, are ancient.

The increasing prevalence of antibiotic-resistant bacterial infections seen in clinical practice stems from antibiotic use both within human medicine and veterinary medicine. Any use of antibiotics can increase selective pressure in a population of bacteria to allow the resistant bacteria to thrive and the susceptible bacteria to die off.

As resistance towards antibiotics becomes more common, a greater need for alternative treatments arises. However, despite a push for new antibiotic therapies there has been a continued decline in the number of newly approved drugs.

Principles of appropriate antimicrobial use exist for prophylactic, empirical and directed therapy, in both hospital and community practice. These principles are summarised in the antimicrobial creed MIND ME.

Appropriate antimicrobial therapy improves patient outcomes, reduces inappropriate and unnecessary antimicrobial use, and reduces adverse consequences, such as antimicrobial resistance and toxicity.

Most viral and bacterial infections are self-limiting—the immune system successfully eliminates many infections. Therefore, antimicrobial therapy is often not required.

MINDME:  The Antimicrobial Creed

M         microbiology guides therapy wherever possible

I           indications should be evidence based

N         narrowest spectrum required

D         dosage appropriate to the site and type of infection

M         minimise duration of therapy

E          ensure oral therapy is used when clinically appropriate

Appropriate antimicrobial prescribing practice includes the following:

  • Clarification of the indication for antimicrobial therapy.
  • Consideration of appropriate microbiological assessment and, if indicated, collection of specimens before the first dose of antimicrobial.
  • Selection of an antimicrobial for the specified indication that is consistent with appropriate clinical guideline recommendations; consider the required spectrum of activity, potential adverse effects, drug interactions and cost, as well as patient factors such as history of antimicrobial hypersensitivity, recent antimicrobial use, and pregnancy and breastfeeding.
  • Selection of the appropriate dose, frequency and route; consider the severity and site of infection, as well as pharmacokinetic and pharmacodynamic parameters that influence dosage regimen prescribing for the appropriate duration; consider specifying a review or stop date.

The 15th edition of the Antibiotic Guidelines has reduced the length of time of treatment for a number of conditions. For example, treatment of urinary tract infections has been reduced from 14 to seven days.

  • Clearly document all antimicrobial therapy in the patient’s medical records and/or medication chart. Documentation should include the indication and the intended duration of therapy before further review or cessation.

This means that antibiotics may not need to be taken until finished; they should be taken according to the intended duration of therapy.

  • When an antimicrobial is prescribed, provide information about the indication and the intended plan for antimicrobial therapy and the potential adverse effects to the patient or the patient’s carer.

The National Prescribing Service Prescribing Practice review  has the following key messages with respect to antibiotic resistance and respiratory tract infections:

  • Antibiotic resistance requires consideration at both a population and individual level.
  • A patient’s beliefs and expectations about antibiotics for acute respiratory tract infection should be established and communication strategies should be tailored accordingly.
  • Encourage self-management of acute respiratory tract infection and explain why antibiotics may not be appropriate.
  • Consider the issue of resistance when prescribing antibiotics.

Antimicrobial stewardship refers to coordinated interventions designed to improve and measure the appropriate use of antimicrobials by promoting the selection of the optimal antimicrobial drug regimen, dose, duration of therapy, and route of administration. This takes into account all the above.

Along with infection prevention and control, hand hygiene and surveillance, antimicrobial stewardship is considered a key strategy in local and national programs to prevent the emergence of antimicrobial resistance and decrease preventable healthcare associated infection.

One simple act which could help reduce the use of antibiotics would be remove the repeat x 1 allowed on the PBS for most antibiotics. Generally speaking, the second course is not needed and if the infection has not improved after the first course, the patient needs to be reassessed.

Pharmacists should encourage patients not to automatically have the repeat prescription dispensed.

Therapeutic Guidelines: Antibiotic, version 15, Therapeutic Guidelines Limited, Melbourne, 2014.

Associate Professor Louis Roller, from the Faculty of Pharmacy and Pharmaceutical Sciences Monash University, was the 2014 recipient of the PSA Lifetime Achievement Award.