With a multidrug-resistant strain reported in Australia, a local respiratory expert says don’t hesitate to test.
Cases of hypervirulent and multidrug-resistant Klebsiella pneumoniae (hvKp) have been reported in Australia and 15 other countries.
One sequence type of hvKp is of particular concern to the WHO: ST23, which is resistant to carbapenem antibiotics and all available beta-lactam antibiotics.
Australia is one of 12 countries to have reported cases of hvKp ST23, along with Algeria, Argentina, Canada, India, Iran, Japan, Oman, Philippines, Switzerland, Thailand and the UK. So far, only three cases were identified in 2023 and reported by the Interim Australian Centre for Disease Control (CDC) working together with the Public Health Laboratory Network (PHLN). The strain is likely to have so far gone undetected in countries without diagnostic capacity.
“If you’ve got a patient that’s coming to see you and they look sick and they’ve got a high fever, think about doing testing, because in this particular infection it could be a real problem to wait for a week,” said Associate Professor Anthony Byrne, the deputy convenor of the Respiratory Infectious Diseases Special Interest Group, Thoracic Society of Australia and New Zealand.
Klebsiella pneumoniae, which is found in the mucous membranes of mammals, including humans, and also in the environment, in places like soil, surface water and on medical devices, is usually an opportunistic infection affecting immunocompromised people in healthcare settings and causing serious illness such as pneumonia, urinary tract infections, bacteraemia and meningitis.
But hvKp infects both healthy and immunocompromised people and is more likely to result in invasive infection than other strains of K. pneumoniae.
“It can spread to other parts of the body, which is unusual for the classical Klebsiella pneumonia,” said Professor Byrne, who practices as a respiratory physician at St Vincent’s in Sydney and lectures at the University of New South Wales.
“This is a type of virulent strain with certain genetic mutations which allow it to break down defensive systems within the body and metastasise to the liver, classically with a liver abscess. This is in someone without established hepatobiliary disease.”
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And from the liver it can spread to the brain, the meninges and the eyes, causing endophthalmitis (an infection and inflammation of the aqueous and vitreous humours of the eye), meningitis and brain abscesses, he said.
“If you’ve got a patient presenting that’s unwell, that might be a young person or any person, then I would have a very low threshold for sending them for a respiratory viral swab. If it’s not viral, the next step I’d suggest would be a blood test, looking at someone’s liver function, their full blood count, their kidney function and markers of inflammation,” said Professor Byrne.
“If they’ve got abnormal liver function tests, raised markers of inflammation, and this person is getting worse, not better, then at that point really consider this diagnosis or other diagnoses where the patient might need blood cultures and a hospital admission.”
Red flags for hvKp, he said, included being younger and “pretty sick” with headaches, high fevers and weight loss.
Someone with a hepatic abscess might also present with systemic symptoms such as fatigue, lethargy and being too sick to work.
Antimicrobial treatments for hvKp ST23 are “very limited”, the WHO said, emphasising the importance of strict infection control measures once it is identified.
But Professor Byrne said it was not known whether the disease could easily spread in the home environment.
“In classical Klebsiella pneumonia, thinking about close contacts is not something that we would typically do. But for hypervirulent strains, in a healthcare setting, it’s important because there are catheters, shared rooms, shared bathrooms. Would I be giving some advice about sharing things in the household? Potentially, in light of this new information. But it’s not 100% clear. I wouldn’t be treating it like covid, for example.”
A Department of Health and Aged Care spokesperson told ARR molecular testing was performed for all identified or presumed carbapenemase-producing Enterobacterales isolates, based on phenotype. But the capacity to perform whole genome sequencing varies around the country.
“CPE, including K. pneumoniae, are target pathogens in Australian [antimicrobial resistance] surveillance,” the spokesperson said. “In most cases these isolates are sequenced. However, testing for virulent genes or markers in K. pneumoniae is not routinely performed.”
In the 2023 Australian report on antimicrobial use and resistance in human health, it was noted that “[t]here are increasing rates of critical antimicrobial resistances in hospitals, particularly carbapenemase-producing Enterobacterales”.
But carbapenem resistance “remains uncommon and is found more often in the Enterobacter cloacae complex than in E. coli or Klebsiella pneumoniae”.
