A helpful new study has combined shoe-leather epi and WGS to establish a transmission rate of CPE in hospitalised patients. Overall, 3 (2%) of 152 exposed patients ended up colonised with the same CPE from 47 index patient exposures. None of the 54 exposed staff ended up colonised with CPE. This transmission rate is a bit lower than I would have expected, but it’s also not zero!

The study was conducted in a large hospital in Seoul, Republic of Korea over a period of 3 years just before the pandemic (2017-2019). All patients admitted to ICU were screened for CRE; CRE was detected outside of the ICU only via clinical diagnostic cultures. Index patients were defined as patients with new CP-CRE that shared a room with other patients. New CP-CRE patients were isolated is single rooms under contact precautions. Exposed patients had to have shared the room with an index patient for at least one day. During this time, a total of 47 index patients, 152 exposed patients, and 54 exposed members of staff were identified.

4 of the exposed patients tested positive for CP-CRE, and 3 of these were a genomic match with the index case, so the overall transmission rate of CPE was 2%. None of the exposed staff tested positive for CP-CRE. On average, the index patients and contacts were together in the same room for 3 days (median, IQR 2-7 days), so this was more than a transient period together.

I suspect some transmission events were missed because contacts were only screened for CPE on one occasion, on average 8 days after the first day of exposure. However, the overall message is reassuring, that CPE transmission doesn’t occur often even when patients are sharing the same space for a couple of days, and transmission to staff is even less common.