Growing worry over bugs that beat even last-resort antibiotics

Carbapenemase producing Enterobacterales, or CPE, is found in the gut bacteria of a carrier. Photo / Centers for Disease Control and Prevention

Scientists have sounded concern over an organism resistant to a type of "last resort" antibiotic which is being seen in a rising number of New Zealand cases this year.

Carbapenemase producing Enterobacterales, or CPE, is found in the gut bacteria of a carrier and is transferred by touch to surfaces, skin or food when that person hasn't washed their hands properly after going to the toilet.

Someone else could then unknowingly transfer the bacteria to their mouth.

This family of organisms was worrying to researchers because they have acquired a gene that enables them to grow in the presence of the carbapenem antibiotics.

ESR microbiologist Dr Kristin Dyet said the bacteria were resistant because they produced a specific enzyme that left the antibiotics inactive - and its rise was partly due to the increased use of the drugs.

What made this more alarming was the fact the antibiotics were used to treat infections caused by multi-drug resistant organisms, and were considered the antibiotics of last resort.

"There are very few, if any antibiotics, available to treat infections caused by CPE bacteria."

While New Zealand had low levels of antimicrobial resistance compared to rates observed internationally, rates were nonetheless on the rise.

So far this year, there have been around 50 cases and most people found to have it here became infected overseas.

Surveillance has linked infections with people receiving care in foreign hospitals – particularly in the Indian subcontinent.

"The rate of exposure to resistant organisms during international travel is likely to be higher than exposure rates in New Zealand."

Infections with CPE, however, remained preventable and extremely rare, and the presence of CPE in the gut did not mean the carrier will get sick.

CPE was detected on standard microbiology tests requested by health professionals, and extra screening was also carried out as part of everyday care in hospital.

However, researchers have called on health authorities to create a national plan to meet the threat.

In a recent paper in the New Zealand Medical Journal, ESR and Auckland District Health Board clinicians said this would have to involve authorities pooling together resources at national and regional scales.

"Nonetheless, such efforts and investment should be regarded as essential in the face of such a serious and urgent public health threat," they wrote.

"While ultimately these measures may only succeed in delaying CPE from becoming endemic in New Zealand, every year free of CPE ensures a safer healthcare system for our patients and buys a little more time for new treatment options and prevention technologies to become available."

Dyet said New Zealand already had in place the Antimicrobial Resistance Action Plan, jointly developed by the Ministry of Health, Ministry for Primary Industries and representatives from across the human health, animal health and agriculture sectors.

"The action plan's vision is that New Zealand manages antimicrobials as a valuable shared resource and maintains their efficacy so they can be used to treat infections in humans, as well as to manage diseases in animals and plants."

CPE was among a list of bacterial isolates regularly referred to ESR's Antimicrobial Reference Laboratory, among them Colistin-resistant E. oli and Klebsiella pneumoniae, Vancomycin-resistant or linezolid-resistant Enterococcus faecium and E. faecalis.