Peer-Reviewed Research Study

Cluster of Carbapenemase-Producing Carbapenem-Resistant Pseudomonas aeruginosa Among Patients in an Adult Intensive Care Unit

MEGAN E. CAHILL, MARTHA JAWORSKI, VICTORIA HARCY, ERIN YOUNG, D. CAL HAM, PAIGE GABLE, KRIS K. CARTER
CDC, MORBIDITY AND MORTALITY WEEKLY REPORT, AUGUST 2023

Introduction
The report discusses an examination into the infections of carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa (CP-CRPA) in an Idaho hospital (Hospital A) between September 2021 and January 2022. The infections present a significant challenge due to the high antibiotic resistance and their ability to spread from person-to-person and via environmental sources. The study focuses on two patients from the same intensive care unit room, with both isolates characterized by specific carbapenemase gene type and multilocus sequence type.

Results
The investigative team focused on the plumbing in the ICU room because Pseudomonas aeruginosa is known to persist in biofilm, a collection of microorganisms that adhere to one another and to a surface, such as a pipe. Water samples and swabs from two sinks and one toilet were collected.

CP-CRPA with the same gene type isolated in the patients was found in one of the sinks, including swab samples from the drain, p-trap (a bend in a sink drain that holds water to block sewer gases), and sink counter. Water samples from the same sink’s p-trap and a toilet also tested positive for a different strain of CP-CRPA.   

Due to the genetic link between the patient isolate and sink isolate, the investigative team concluded that the most likely source of the outbreak was the ICU room sink.

Conclusion
The report concludes that as of December 2022, no further CP-CRPA had been reported by Hospital A, suggesting the preventative measures implemented were successful. The work highlights the importance of collaboration between healthcare facilities and public health agencies, especially in identification and response to CP-CRPA clusters in a healthcare setting. Such cooperation, alongside the implementation of robust sink hygiene interventions, is critical in controlling the spread of such resistant infections.