MIddlemore Hospital in Auckland recently notified that it had three patients infected with Carbapenem-resistant organisms (CRO) and this is something we should all be very worried about. The World Health Organisation (WHO) has been running a global campaign to raise awareness of antibiotic resistance because it is a major threat to everyone’s health. That reported cases of CRO are increasing in New Zealand is terrifying because once it gets established, it is almost impossible to get rid of and we are fast approaching a time when the simplest of infections could kill you.
So what are carbapenems? The name comes from a class of penicillin antibiotics used in hospitals when all others have failed. They act on gram-negative bacteria, which includes bacteria that normally are no problem to us and live happily in our bodies. The name comes from the identification method used to test the presence of bacteria. Gram-negative bacteria don’t retain the crystal violet dye, while gram-positive do.
These bacteria are found everywhere and include Escherichia coli (E. coli), Salmonella, Shigella. They are tough buggers as their outer cell membrane protects them from many antibiotics and they are often responsible for infections caught in hospital.
Imipenem-cilastatin molecular model. One of the carbapenem family of antibiotics that represent the last resort in the treatment of resistant bacterial infections sometimes called superbugs.
Although we all have them, the danger is when they get into wounds or vulnerable people with suppressed immune systems are exposed, they can cause nasty infections. But more than that, they exchange information easily with other bacteria. They have a loop of free-floating DNA called a plasmid, which they can pass back and forth with other bacteria, so if we come into contact with carbapenem-resistant bacteria, they will exchange plasmids and convert all the bacteria in our bodies to become drug resistant as well – scary!
Because of this ability, bacteria are systematically acquiring resistance to each class of antibiotics. Carbapenems are vital as they are considered to be the most reliable last-resort treatment and safer to use than other last line drugs against multi-drug resistant bacteria.
To date, most cases in New Zealand have been associated with travel as CRO are already endemic in many parts of the world, particularly India. In January 2017 an American woman , who had broken her leg and was treated while traveling in India, was admitted to hospital when she returned to the US with a secondary infection. No antibiotic treatment available in the US could treat her and she died of a secondary infection caused by a CRO.
Last week, the National Burns Unit at Middlemore Hospital in Auckland notified that three patients had infections caused by CRO. The first one had acquired the bacteria offshore, but it seems the other two patients caught it from him when they shared the same ward. According to the hospital, they screen high-risk patients for CRO, so how did the two other patients get cross-infected? The main path of infections in hospitals is via healthcare workers and equipment, and CRO are incredibly difficult to get rid of. A hospital in Dandenong, Australia tracked a CRO infection reservoir to the sinks in the ICU and, despite multiple sterilization attempts, finally had to rip out the sinks and replace them to get rid of the bacteria.
Worryingly, the incidence of infections is steadily climbing. In 2009, there was one reported case of CRO in NZ, by 2017 there were 54 and 11 percent had no history of travel meaning they had acquired the CRO in New Zealand.
Having CRO within our systems doesn’t cause a problem until we, or someone close to us, falls ill. But having them in your system also means you are a carrier and they can be passed along to others. The more people that have them in a population, the higher the risk of vulnerable people getting infections that can’t be treated.
This is the scary part – how to stop them becoming endemic in New Zealand? According to a paper written by a group of microbiologists, we have a small window of opportunity to stop that from happening. It’s a bit like a biosecurity incursion – think foot and mouth disease – when it is detected every animal in a wide radius is burnt to stop it spreading, but obviously you can’t do this for humans, so what are our options?
Remember, gram negative bacteria are everywhere in the environment and they can share the antibiotic resistant to non-restart strains, so as soon as they connect with other bacteria, the resistance is passed along. For example, someone carrying CRO touches a surface, say the keypad of an EFTPOS machine, you touch the same surface and the bacteria enters your system, colonises your bacteria and so on, and so on.
The question is, at what level of infections does this become critical and urgent measures are taken to stop the spread in New Zealand, or is it already too late?
The Ministry of Health does have an action plan, but it is set to roll out over five years – which will probably be too late and, going by the experience with every biosecurity incursion in New Zealand, I wouldn’t be too hopeful. According to the paper’s authors, we have to act now, before it is too late.
So what can we do? One of the major sources of CRO is overseas medical treatment. Medical tourism is a major contributor and even if a stay in an offshore hospital goes well, you can return with CRO happily at home in your bowels, and you are now a carrier.
The papers’ authors also suggest stronger healthcare biosecurity measures in New Zealand hospitals such as screening everyone who has been to an overseas hospital in the last year or travelled to high prevalence areas. If I was a patient, I would also want to know that the healthcare workers treating me were also clear of CROs, so why aren’t they screened as well, especially in high-risk units like ICU and the burns unit?
What can we as individuals do? Unfortunately, not much except being aware of the risk of acquiring CRO when we travel overseas. It may not be worth the risk of getting your teeth fixed in Thailand if you return with a body full of CRO.
It is terrifying as the implications are that soon no antibiotics will work and we will return to the pre-world war two era when people die from simple infections. It may not be every bacteria everywhere, but when it happens and how widespread it becomes is still an open question. New Zealand may still have time to stem the tide – perhaps.