Following a deadly outbreak of hospital-acquired pneumonia in China, a team of researchers there has identified the cause to be a newly-discovered antibiotic-resistant strain of Klebsiella pneumoniae
that has proven lethal.
Part of the family of “superbugs” called carbapenem-resistant Enterobacteriaceae
(CRE), Klebsiella bacteria
have plagued health care settings in recent years. In fact, these pathogens have managed to form resistance to nearly all available antibiotics including carbapenems, a class of beta-lactam antibiotics that has had past success in treating infections caused by Klebsiella
species as well as Escherichia coli
bacteria. These hard-to-treat infections typically occur in hospital patients or nursing home residents, individuals who are susceptible to drug-resistant bacteria after taking long courses of antibiotics and/or have been on devices such as urinary catheters, intravenous catheters, or ventilators. CRE bacteria are one of the biggest drug-resistant threats
according to the Centers for Disease Control and Prevention (CDC), causing an estimated 9,000 infections and 600 deaths each year. Other drug-resistant threats include pneumonia, bloodstream infections, wound or surgical site infections, and meningitis.
In a new study
recently published in the journal The Lancet Infectious Diseases
, researchers from the Hong Kong Polytechnic University investigated a deadly outbreak of K. pneumoniae
that occurred in a Chinese hospital in 2016. From late February to April of that year, 5 patients between the ages of 53 and 73 at a new branch of the Second Affiliated Hospital of Zhejiang University developed cases of severe pneumonia following surgery, antibiotic treatment, and having been placed on ventilators. None of the patients’ infections responded to antibiotic treatment, and all five individuals died from either severe lung infection, multiorgan failure, or septic shock.
The researchers found that while all five cases involved carbapenem-resistant K. pneumoniae
strains belonging to the ST11 type – the most prevalent type in China – the strains in this outbreak caused much more severe infections and higher mortality than other carbapenem-resistant strains. After isolating the bacterial strains from sample specimens from the patients and subjecting them to phenotypic and genotypic characterization, the researchers identified virulence genes that had never been seen in ST11 type strains. They determined that the infections were caused by the convergence of drug-resistant and highly virulent forms of K. pneumoniae
, forming new superbug strains which the authors dubbed ST11 carbapenem-resistant hypervirulent K. pneumoniae
or ST11 CR-HvKP. The new strains are highly resistant to treatment and are capable of causing lethal infection in the lungs, invading the bloodstream, and infecting other organisms.
The ST11 CR-HvKP strains in the investigation were not susceptible to colistin, considered to be the last resort antibiotic for CRE infections, either alone or in combination with other drugs. Senior author Chen Sheng, PhD, told Contagion ®
that his research group is the first to discover the superbug, which could be treatable with a combination of avibactam and ceftazidime that is not currently available in China but is available in the United States. “I can't predict it without data in China,” he says, noting that the superbug may not be susceptible to the combination for long. “Based on the data from the United States, the carbapenem-resistant K pneumoniae
could develop resistance to avibactam and ceftazidime very quickly.”
In the wake of this potential threat to public health, the Chinese hospital where the outbreak occurred has implemented a new infection prevention and control policy, which includes screening and isolation for patients with CRE, along with practicing good hand hygiene and performing equipment disinfection practices. While the new superbug has not been found in the United States, the CDC
recommends that hospital clinicians take similar precautions to prevent the spread of drug-resistant K pneumoniae
and other superbugs.
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