Urinary superbugs: Are we going about it wrong?

Current guidelines for the treatment of UTIs may be increasingly ineffective amid alarming rates of antibiotic-resistant E. coli found in testing, according to new research from the University of New South Wales (UNSW).
 
The study, published last week in Open Forum Infectious Diseases, is the largest of its kind in Australia and analysed more than 775,000 bacterial isolates from Australian community, hospital and aged care settings from 2016 to shed light on antibiotic resistance trends.
 
Co-author Associate Professor Li Zhang from UNSW’s School of Biological and Biomedical Sciences admits that even she was surprised by the study’s key findings.
 
Hospitals have long been considered the primary hotbeds for antibiotic-resistant superbugs and for generations, GPs and doctors from other disciplines have traditionally used trimethoprim as the first line empirical antibiotic for treatment of UTIs.
 
However, Professor Zhang’s study potentially turns both these presumptions on their head.
 
The new research suggests that prevalence of antibiotic-resistant E. coli in aged care facilities has now overtaken hospitals and an alarming amount – up to 30% – of these bacteria are now resistant to standard treatment with trimethoprim.
 
‘Firstly, I didn’t expect the antibiotic resistance to be so high to trimethoprim,’ Professor Zhang told newsGP.
 
‘Secondly, I always thought hospitals had the highest rates of resistant E. coli, but actually, in aged care it is even higher.’
 
UTIs represent a significant health burden in Australia and are among the top five most common causes of preventable hospitalisations across the country, according to the Australian Institute of Health and Welfare.
 
The One Health antimicrobial resistance economic perspective by the University of Technology Sydney showed they account for 2.62 million GPs visits per year and cost the health system an estimated $909 million annually.
 
Professor Zhang therefore advocates for a revision of current guidelines on the treatment of UTIs. At present, the Therapeutic Guidelines recommends that trimethoprim be used to treat uncomplicated urinary tract infections. However, this does not necessarily take into account that E. coli is increasingly resistant to this antibiotic.
 
Furthermore, the Therapeutic Guidelines do not make any distinction between which antibiotics should be used in aged care, which again fails to account for the increased prevalence of superbugs in these settings.
 
‘Personally, I don’t think trimethoprim should be the first line anymore for community and aged care facilities and we should also look at specific guidelines for aged care,’ Professor Zhang said.
 
The study indicates that resistance to nitrofurantoin in E. coli is in the order of 10% which is far less common than to trimethoprim. This raises the question as to whether Australian guidelines should actually be recommending the use of nitrofurantoin as the first line antibiotic treatment for UTIs, as has now become the practice in the United Kingdom.
 
However, a relatively higher rate of allergic reactions and a more limited body of evidence around the drug’s use have traditionally made change difficult.
 
Dr Zhang believes more research needs to be done to expand upon the findings of the study and inform policymakers.
 
‘We know that the prevalence of antibiotic-resistant E. coli is the highest in aged care. The next step is to ask why,’ she said.
 
‘Is it because older people in aged care facilities have visited hospitals and acquired the resistant UTI there? Or is it because antibiotic resistant strains are circulating in the aged care facility itself? Is it even perhaps because aged care residents are typically an older population who may have had a lifetime of repeated exposure to antibiotics?
 
‘We will now want to look at the genomes of the isolates in our study and analyse their antibiotic-resistant genes to find the bacteria’s source. This will be very useful for policy making to control antibiotic resistance.’
 
In general, antimicrobial resistance continues to be a major problem for aged care residents.
 
The most recent Antimicrobial Stewardship in Australian Health Care report states that three in 100 aged care residents in Australia have an infection at any one given time. Meanwhile, six in 100 are receiving antibiotics at any one point in time and between 50–80% of aged care residents receive at least one course of antibiotics per year.
 
Professor Paul Glasziou, a GP and Director of the Institute for Evidence-Based Healthcare at Bond University, agrees that use of nitrofurantoin instead of trimethoprim to treat UTIs could help reverse antibiotic resistance.
 
However, he also warns that we must be mindful of the specific side effects, for example, the increased risk of allergic reactions to nitrofurantoin when compared with trimethoprim. 
 
‘Resistance is reversible,’ he told newsGP.
 
‘Antibiotic resistance is a selection process rather than the development of new genes. So if you stop using a particular antibiotic, you reverse the selection process.
 
‘It is a trade-off though … how willing are you to accept the increased risk of allergy to improve resistance?’
 
Professor Glasziou also reminds us of the hidden complexity surrounding proper diagnosis of true UTIs and appropriate treatment with both medication and non-medication therapies. He ultimately calls for GPs to lead the treatment of UTIs.
 
‘Multiple studies show lower the rates of recurrent infections with good hydration, ingestion of cranberries and the use of hipprex,’ he said.
 
‘Many patients clearly need antibiotics for their UTIs; however, you need to confirm that it is a true UTI using microscopy and sensitivity testing, at least for the first episode.
 
‘One of the things that worries me about … pharmacists prescribing antibiotics for UTIs in Queensland, is there often hasn’t been a confirmation that there is a true infection and not something else such as urethral irritation.
 
‘That’s what GPs are for – and I’m not sure the pharmacists should be doing it.’
 
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aged care antimicrobial resistance superbugs trimethoprim UTIs