To better understand the molecular drivers behind resistance to available antimicrobial treatments, researchers at the Centers for Disease Control and Prevention (CDC) recently conducted a whole-genome analysis of an isolate of Klebsiella pneumoniae cultured from a patient in the United States. The patient, who had a hip infection that did not respond to antibiotics, died in 2016. Their results were published today in mBio.
The microbe is one of the first K. pneumoniae strains reported to the CDC that was resistant to all 26 antibiotics available for treatment, says Tom de Man, a bioinformatics expert at the CDC who led the study.
De Man and his collaborators identified four genes known to confer resistance to beta-lactams, a family of broad spectrum antibiotics often used to treat gram-positive and gram-negative infections. Two of those genes were found on the chromosome. Two were found on plasmids. Other genes identified in the analysis are associated with resistance to fosfomycin, tetracyclines, and other antibiotics.
The isolate at the center of the new study belongs to a strain type that has spread around the world. Plasmids identified in the study also suggested this microbe may be related to resistant bacteria that have been reported in other countries including China, Nepal, India, and Kenya.
The genomic analysis will provide public health workers with better information about resistant infections, says de Man. Knowledge about which strains have which genes can help guide the development of more precise tests that can be used at hospitals and health centers. "We can find new resistance mechanisms," he says. Tests informed by genome-wide analyses may help epidemiologists recognize and contain resistant strains before they spread to other patients. Though it's not possible now, in the future genomic information might help guide treatment decisions and strategies.
In the last two years, the CDC has established a network of laboratories across the United States that track the emergence and spread of resistant pathogens like K. pneumoniae. Those centers are designed to quickly identify dangerous microbes with the goal of stopping transmission as quickly as possible.