A Hospital Sink Spread Drug-Resistant Pseudomonas in an Idaho ICU

Carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa (CP-CRPA) is hard to treat because of its antibiotic resistance, and it spreads readily in health care settings — person to person and from sink drains and toilets. This report describes how Idaho traced a cluster to a single ICU sink.

Two patients, one room

In each case, CP-CRPA appeared only in the last of several sputum samples, pointing to hospital-acquired infection.

• Idaho's state lab found carbapenemase activity but none of the four most common genes. Whole genome sequencing at the Utah Public Health Laboratory, part of CDC's Antibiotic Resistance Laboratory Network, found a rarer one: IMP carbapenemase type 84 (blaIMP-84), in sequence type ST235.
• Patient 2's isolate matched, linking the two cases. Between their stays, 16 other patients occupied room X (median 3.5 days); five had respiratory cultures, none positive.
• Patient 2 was moved to a long-term care facility and not placed on contact precautions for her 10-day stay — the hospital's recommendation hadn't reached that facility's infection preventionist. Screening there and in the ICU found no spread.

Finding the source

On March 21–22, 2022, the state's health care–associated infections team visited, reviewed policies and patient histories, and — because P. aeruginosa survives in biofilm in plumbing — sampled room X's two sinks and toilet and a ventilator used by patient 1.

The same strain turned up in one sink: its drain, P-trap and counter; related bacteria were also in the P-trap water and one toilet sample. Sequencing showed the patients' isolates were closely related to each other and to the sink drain isolate.

Stopping it

Recommendations included:

1. close room X until the sink drain was treated with an EPA-registered foaming disinfectant for drain biofilm;
2. add splash guards to sinks;
3. use the disinfectant weekly in all ICU room drains;
4. adopt sink hygiene practices, such as dedicated handwashing sinks;
5. make sure infection preventionists receive contact-precaution notices when patients transfer;
6. screen the next occupants of room X (for example, the next 10);
7. keep sending resistant isolates to the state lab.

The disinfectant was applied May 9–27, 2022 (daily for 3 days, then every 3–5 days four more times). Eleven weeks after the first visit, the sink and drain tested negative, and as of December 2022 the hospital had reported no more cases.

Takeaways

Collaboration among the hospital, public health programs and laboratories — including testing resistant isolates for carbapenemase genes, genome sequencing and sink hygiene — identified and ended the cluster. Patients on prolonged mechanical ventilation are at higher risk. How often drains must be disinfected to break up biofilm isn't settled, though some studies suggest every 3–7 days can help.

Sources

Based on "Cluster of Carbapenemase-Producing Carbapenem-Resistant Pseudomonas aeruginosa Among Patients in an Adult Intensive Care Unit — Idaho, 2021–2022," Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention; a work of the United States government in the public domain.