Genomic sequencing reveals MRSA spread within, between ICUs
Whole-genome sequencing revealed the spread of MRSA strains among patients, health care workers and the environment, including within — and even between — ICUs, according to findings in Clinical Infectious Diseases.
“Ebola led to renewed interest in personal protective equipment for preventing the spread of potential pathogens to the health care worker (HCW), the hospital environment and other patients,” Kyle J. Popovich, MD, MS, associate professor in the division of infectious diseases at Rush Medical College, told Healio. “For pathogens such as MRSA, hospitals may choose to place patients colonized or infected with this pathogen on contact precautions. HCWs wear personal protective equipment (PPE) when caring for a patient on contact precautions to prevent self-contamination. However, there can be errors in the donning and doffing of PPE, and these errors could impact subsequent HCW contamination.”
According to Popovich, one potential mode for hospital transmission of MRSA is by HCWs who contaminate their hands, equipment or clothes during patient contact. Because whole-genome sequencing (WGS) can better differentiate endemic MRSA strains, Popovich and colleagues wanted to use this technique to improve their understanding of the origins of HCW contamination with MRSA during a patient encounter that involved donning and doffing of PPE.
The researchers enrolled HCWs from four adult ICUs who were caring for patients on MRSA contact precautions between September 2015 through February 2016 to study the spread of MRSA. They collected samples from patient body sites and high-touch surfaces in their rooms. Additionally, HCW hands, gloves and PPE were sampled both before and after the patient encounter. WGS was then used to compare isolates from patients, HCWs and the environment.
According to Popovich, WGS demonstrated that MRSA isolates from the patient, HCW and environment generally were genetically similar for “the vast majority” of patient encounters, which suggests the spread of MRSA within that HCW-patient interaction. In addition, WGS allowed them to detect a small minority of genome-defined clusters of highly related MRSA isolates from different patient encounters. This enabled the researchers “to detect unusual events where there appeared to be spread of MRSA outside of the patient encounter,” Popovich said.
“WGS, in conjunction with robust epidemiologic data, allowed identification of possible unusual opportunities for spread of MRSA strains in the ICU,” she said. “WGS allowed us to further move the needle in our understanding of MRSA transmission in an ICU and, in addition, highlighted important opportunities for infection control improvements to help interrupt nosocomial spread of MRSA.”