Wednesday, September 25, 2013
Superbugs and Prostate Biopsy
I am deeply concerned about the rising incidence of so called ‘superbug’ infections associated with prostate biopsy. These bacteria are resistant to the great majority of antibiotics we have available for use and the only ones that work generally have to be given through the veins. These bacteria have become particularly prevalent in Asia where the indiscriminant use of antibiotics in agriculture has lead to the breeding of antibiotic resistant bacteria in the community. When you are well, they are of no risk and they live harmoniously within your body. Should you be placed in circumstances where your own bacteria turn against you and you happen to have the ‘superbug’, this can lead to serious infection as conventional antibiotics are not effective. For those who wish to get technical, with the term ‘superbug’, I am referring to the so called extended spectrum beta lactamase producing bacteria (ESBL). With increasing travel to Asia, growing numbers of Australians will carry these bacteria within their intestines. Any procedure that carries ANY risk of infection, which happens to include prostate biopsies, will carry a risk of serious infection.
The article published in the The Age today is entitled “Prostate biopsy blamed for preventable superbug deaths”. This headline will understandably place fear in every man who is about to be scheduled to undergo a prostate biopsy should they read this piece. However, there needs to be some perspective on the calls for urgent rectification of the problem of superbugs by having all public hospitals purchase the equipment that will enable the risk of any prostate biopsy related infection to be eliminated. The typical cost of such equipment is $150,000 and multiply this by the number of public hospitals, it poses a massive infrastructure cost and represents monies that have to be taken from somewhere else in the health budget.
Transperineal prostate biopsy (TPB) creates significant burdens on resource utilization. TPB require a general anaesthetic and day surgery admission to hospital as well as utilization of precious operating theatre time. Almost all Transrectal ultrasound prostate biopsies (TRUSPB) are performed in an outpatient setting and typically take 15 to 30 minutes including turnover time. A TPB can typically utilize as much as 45 to 60 minutes of operating time including turnover time. More than 20,000 prostate biopsies are performed in Australia each year and if every one of these were to be immediately pushed into the hospital system, urological surgical resources would be pressed to cope. Waiting lists would likely significantly increase and it is highly unlikely that there would be increased allocations of operating theatre sessions for urological procedures.
Figure 1. Transperineal biopsies performed in the operating theatre setting
Even if a reliable mechanism was found to perform the procedure under local anaesthetic, the procedure would still need to be performed in the hospital setting as appropriate infrastructure such as physical floor space and the operating table which enables coupling to the transperineal biopsy equipment is simply not readily available in the outpatient setting.
The majority of men would need to take the day off for the procedure and often the following day given that they have had a general anaesthetic. If the procedure is performed as a TRUSPB under local anaesthesia, most are able to return to normal activities either the same or following day.
There are certainly issues with infections associated with TRUSPB. These men can become very sick and a small number of cases may require admission to Intensive Care Units. Men should however, be reassured that their risk of dying from a prostate biopsy infection is extremely small. The Victorian data demonstrates a reported incidence of 2 deaths over the past five years. With over 7000 biopsies being performed in Victoria each year, this equates to an incidence of 2 out of over 35,000 prostate biopsy procedures (<0.006%) and in the article published in the Age today, these are attributed to the ‘superbugs’. When we look at the mortality rates associated with infections, a recent paper found that the incidence of community acquired ESBL sepsis was around 10%. In a mix of patients with healthcare related and community acquired ESBL sepsis, the mortality rate was as high as 20%. The patients most likely to die were elderly or had significant medical co-morbidity and exactly the type of patient who perhaps prostate biopsy ought not be undertaken.
There are relatively few invasive procedures that do not carry a risk of infection although transperineal prostate biopsy is one where the risk is negligible if not zero. This data has been repeatedly confirmed and provide a compelling argument to switch completely from TRUSPB to TPB. But are there any medical reasons why we should reflect on this assertion? A recent Australian study published this year, the risk of acute urinary retention was 4.2% whereas following TRUSPB, it is a very rare event.
Rather than see panic stations with public outcry and a call for all hospitals to be immediately armed with the expensive equipment, other processes should be enter into practice with a greater level of urgency. We have to be pragmatic and recognize that hospitals are not about to be funded for this equipment in the immediate future and other strategies need to be sought in the meantime.
With the recognition that too many men diagnosed with prostate cancer die with the disease rather than from it, we need to better select the men in whom prostate biopsies are recommended. We also need better risk assess which men are more likely to carry the ESBL ‘superbug’ and a history of recent travel to Asia should be explored. We also need to get smarter about either using or searching for simple strategies to minimize the risk of ESBL infection such as performing rectal microbial swabs in advance of the prostate biopsy, use of antiseptics such as betadine suppositories in the rectum or dipping the biopsy needle in chemicals such as formaldehyde before each pass. These strategies need more work but represent that the profession recognizes more needs to be done. With growth in the use of MRI scans prior to prostate biopsy, it is also possible that fewer biopsies will need to be taken and there is the potential that fewer numbers of biopsies taken may ultimately be proven to be associated with less risk of infection. We can also potentially improve the recovery from infection by having men appropriately counseled to attend for assistance immediately with the onset of infection rather than ‘sitting on it overnight and attending in the morning’ – when bacteria are capable of double in numbers as fast as 20 minutes for some, early presentation can make a huge difference to recovery.
In conclusion, ‘superbug’ infections are a serious problem and we need to do more to minimize the risk to our patients on many fronts. I believe that transperineal prostate biopsies are one way forward, but the practicalities and priority needs to be considered in the context of other health priorities.
Disclosure - A/Prof Henry Woo has access to TPB equipment at his hospital and does perform this procedure in selected men. The vast majority of his patients undergo TRUSPB under a local anaesthetic prostate block in an ambulatory outpatient setting.