AsianScientist (Sep. 7, 2017) – Scientists in Hong Kong have discovered a hyperresistant and hypervirulent superbug in a hospital in China. Their findings have been published in The Lancet Infectious Diseases.
ST11 Klebsiella pneumoniae strains proliferate in the gastrointestinal tract (GI tract) of humans and animals and may cause opportunistic infections such as pneumonia in clinical settings. These strains, after acquiring plasmid encoding a carbapenemase gene, become resistant to carbapenem antibiotics and are thus untreatable.
Occassionally, ST11 strains further evolve to become ST11 carbapenem-resistant hypervirulent K. pneumoniae (ST11 CR-HvKP) strains through the acquisition of hypervirulence plasmids. The ST11 CR-HvKP strains do not only infect the lungs and cause pneumonia, but also invade the bloodstream and other internal organs. Due to their hypervirulence and phenotypic resistance to commonly used antibiotics, ST11 CR-HvKP strains may cause untreatable and fatal infections in relatively healthy individuals with normal immunity.
In this study, Professor Chen Sheng of Hong Kong Polytechnic University, collaborating with Professor Rong Zhang from the Second Affiliated Hospital of Zhejiang University, conducted an investigation into a fatal outbreak of pneumonia in the Second Affiliated Hospital of Zhejiang University in China in February 2016.
The study involved five patients who underwent surgical operation for multiple-trauma. All of them were later infected in the intensive care unit (ICU) and developed severe pneumonia. They eventually died of septicaemia and multiple organ failure. The causative agent of the deaths of these five patients was later attributed to ST11 CR-HvKP strains.
Although the transmission route of ST11 CR-HvKP strains remains unclear, the bacteria possess a mucoid outer layer which enables them to stick to various materials such as the surface of medical devices and tubing as well as other surfaces in the ICU. The researchers highlighted that medical equipment such as ventilators and different catheters may have been responsible for transmitting these new superbug strains.
Human-to-human transmission may also be possible, mainly in hospital settings. Hence, the researchers recommend that hospitals adopt improved infection prevention and control policies, especially in ICUs. Novel strategies must also be devised to prevent ST11 CR-HvKP from proliferating extensively in the human intestinal tract where they were detected by the polymerase chain reaction method targeting specific resistance and virulence genes.
The researchers further demonstrated that the use of colistin, the last-resort drug for carbapenem-resistant enterobacteriaceae infections, alone or in combination with other drugs, was not effective in treating infections caused by ST11 CR-HvKP. They proposed ceftazidime or avibactam as alternative treatments, although ST11 CR-HvKP may develop resistance to this antibiotic very quickly based on the clinical data from the US.
The article can be found at: Gu et al. (2017) A Fatal Outbreak of ST11 Carbapenem-resistant Hypervirulent Klebsiella pneumoniae in a Chinese Hospital: A Molecular Epidemiological Study.
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Source: Hong Kong Polytechnic University.
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