Antibiotic resistance in Australia: here and now

• Carefully consider if a health condition is self-limiting before prescribing antibiotics: Antibiotics are not recommended as routine therapy for acute otitis media, acute tonsillitis, acute sinusitis or acute bronchitis, all of which mostly resolve on their own.
• When antibiotics are necessary, prescribe the narrowest-spectrum antibiotic at the appropriate dose and duration: Consult relevant guidelines for appropriate dose and duration depending on the site and type of infection, and choose the narrowest-spectrum antibiotic to treat the likely pathogen.
• Provide clear instruction to patients regarding appropriate use and disposal of prescribed antibiotics: Ensure patients understand the directions provided, to reduce the risk of treatment failure or relapse. Advise them to return unused antibiotics to the pharmacy for disposal

Since the introduction of antibiotics the Australian healthcare system has relied heavily on these medicines to prevent and treat bacterial infections across all age groups.^1,2

Over time it has become appreciated that antibiotic use increases antibiotic resistance at an individual level as well as at a population level.

Drug-resistant ‘superbugs’ have emerged as a major global health issue, and are now often reported in the media.^3,4,5

But how common is antibiotic resistance, really? Is it that much of a problem right now, and what can health professionals do about it?

In 2014 more than 30 million prescriptions for antibiotics were provided to Australians through the PBS/RPBS, and nearly half of the Australian population were prescribed at least one course of antibiotics.⁶

In the community setting the most commonly prescribed antibiotics in Australia are amoxicillin, cefalexin and amoxicillin–clavulanate.⁶

Most antibiotic prescriptions are provided by GPs (88%), with other primary care prescribers (dentists, optometrists, midwives and nurse practitioners) issuing a small proportion of total antibiotic prescriptions.⁶

Of the penicillin and cephalosporin prescriptions dispensed in 2014 in the community, moderate- and broad-spectrum agents are being prescribed more often (65% and 25%, respectively), while narrow-spectrum agents only accounted for 8% of prescriptions.⁶

Bacteria can acquire resistance through spontaneous mutation or, more commonly, by gene transfer from other bacteria.

Thus, resistance can spread when resistant populations multiply and confer resistance to the next generation (a visual representation of this has recently been created by scientists at Harvard University), or when transfer of resistant traits occurs within and between bacterial species.¹

Transfer of antibiotic-resistant bacteria and their genes in healthcare settings and the community contribute to the emergence of antibiotic resistance.⁷

Increased rates of resistance have been observed to many frequently used antibiotics and, in some cases, to antibiotics that are considered to be last-resort.⁷

Penicillins continue to be the most commonly prescribed group of antibiotics in Australia (44% in 2014, compared with 46% in 1994).⁶ However, recent Australian data suggest their efficacy against some high-priority bacteria may be at risk.

For example, resistance in Escherichia coli occurred at a rate of about 20% for amoxicillin–clavulanate and around 50% for ampicillin or amoxicillin alone, with about 13% of cases showing multidrug resistance in 2014.⁶

Reports are also emerging of resistance to ‘reserve’ antibiotics such as the quinolones, the carbapenems and vancomycin.⁷

In Australia, Enterococcus faecium resistance to vancomycin, an antibiotic used in patients with complicated infections, methicillin resistance or hypersensitivity to penicillins,⁸ is almost 50%, which is among the highest in the world (Table 1).⁶

MIC: mean inhibitory concentration

Table 1. A summary of some high-priority organisms and rates of antibiotic resistance (hospital and community) in Australia⁶ 

A recent news release reported that a significant increase in the proportion of N. gonorrhoeae strains with reduced susceptibility to azithromycin was observed between January and March 2016.³

Although all strains remain susceptible to ceftriaxone,³ the RACGP recommended that physicians should be on the lookout for treatment failures in patients with gonorrhoea, and remember to collect a specimen for culture when failure is suspected.³

The RACGP has also advised GPs to use culture-based methods for diagnosis of gonococcal infections when possible, to allow for resistance testing.³

Evidence suggests that inappropriate antibiotic prescribing by health professionals may be decreasing. According to BEACH data for example, systemic antibiotics prescribed for acute URTIs dropped from 32.8% of presentations in 2011–2012 to 29.0% in 2013–2014.⁹

However, prescribing data indicate that antibiotics are still being frequently prescribed in situations that are not consistent with evidence-based guidelines, and that antibiotic type is sometimes not optimal.

High-volume prescribing for URTIs

Seasonal fluctuations in the prescribing rates of some antibiotics such as macrolides (eg, azithromycin) have been observed to peak during winter, suggesting a link with treatment of viral infections such as colds and influenza.⁶

Among Australian practice patients prescribed a systemic antibiotic who also had an indication recorded, antibiotics were prescribed in more than 50% who had colds and other URTIs,^a although routine use is not indicated or recommended by guidelines for these situations.⁶

^a Data collected from general practices (n = 182) enrolled in the NPS MedicineWise MedicineInsight program.

Potential overuse in patients with acute tonsillitis, acute or chronic sinusitis and acute otitis media

While systemic antibiotic therapy remains indicated in certain patient presentations and key high-risk patient populations for the treatment of acute tonsillitis, acute or chronic sinusitis, or acute otitis media (AOM), there is increasing recognition of their limited role in most uncomplicated presentations.

NPS MedicineWise MedicineInsight data on antibiotic prescribing rates for acute tonsillitis, acute or chronic sinusitis, or acute otitis media have been compared with recommended treatments in Therapeutic Guidelines.⁶

Results indicate that antibiotic prescribing rates far exceeded the recommended ranges set by the European Centre for Disease Prevention and Control.

For example, 91% of patients (age > 1 year) with acute tonsillitis received a systemic antibiotic, when the acceptable rate of prescribing is suggested to be < 20%.^6,10

Additionally, in many cases, the antibiotic prescribed was not the first-line agent recommended by guidelines, and repeat prescriptions were provided when not necessarily required.⁶

Antibacterial resistance reduces the effectiveness of available treatments and increases the risk of spreading resistant bacteria to others.

With the pipeline of new antibiotics limited,⁷ now more than ever it is crucial to carefully consider a decision to prescribe antibiotics, particularly for bacterial infections that are usually self-limiting.^7,11

GPs and other prescribing health professionals are in a prime position to address the issue of antibiotic resistance.¹¹

To minimise antibiotic resistance, NPS MedicineWise recommends only prescribing an antibiotic:¹¹

• when benefits to the patient are likely to outweigh the potential harms 
  
• of the narrowest spectrum to treat the likely pathogen
  
• at the appropriate dose and for the appropriate duration.
  

The Australian Therapeutic Guidelines recommend health professionals follow the principles of MINDME when prescribing an antibiotic:⁷

Microbiology guides therapy wherever possible

Indications should be evidence-based

Narrowest spectrum required

Dosage individualised to the patient and appropriate to the site and type of infection

Minimise duration of therapy

Ensure oral therapy is used when clinically appropriate

Remember to consider antibiotic resistance when deciding whether to prescribe antibiotics for patients presenting with acute RTIs, and to avoid prescribing an antibiotic for likely viral infections and other self-limiting RTIs.

Prescribers may also refer to the Choosing Wisely website for recommendations supporting appropriate use of antibiotics.