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Superbugs on scopes: how UCLA lab found the outbreak

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Anne Ford

August 2015—It sounds a bit like an Agatha Christie story: Two hospital patients, two lengthy stays, two adjacent but separate rooms. Patient A comes in with a Klebsiella pneumoniae carbapenemase-producing isolate. Patient B doesn’t . . . but within 30 days, he’s acquired it. How?

That’s the question Romney Humphries, PhD, section chief of clinical microbiology in the Department of Pathology and Laboratory Medicine at UCLA Health System, found herself asking recently.

Just like the plot of a classic murder novel, her inquiry—which she discussed as part of “Superbugs on Medical Devices—The UCLA Experience,” a talk at this year’s American Society for Microbiology meeting—yielded additional mysteries, a couple of red herrings, an exciting conclusion, and a few tantalizing loose ends.

After learning in late 2014 of the possible patient-to-patient KPC transmission, Dr. Humphries turned to the Los Angeles County Department of Public Health laboratory, which performed pulsed-field gel electrophoresis strain typing on the isolates. “But it was fairly inconclusive, partly because all our carbapenem-resistant Klebsiella pneumoniae in the Los Angeles area are fairly similar, and so it was hard to really figure out what was going on,” she explained.

Two of UCLA Health’s clinical microbiology fellows, Shaun Yang, PhD, and Peera Hemarajata, PhD, then had the idea of trying whole genome sequencing. “So they pulled these two isolates out of our collection and did some DNA prep, and about the time they were getting ready to send the isolates off for sequencing, they were chatting with the infectious diseases service, who mentioned they had a new patient with a CRE,” Dr. Humphries said. Just for the heck of it, Drs. Yang and Hemarajata decided to test an isolate from that third patient as well.

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