Comparing Species of VRE in Nursing Facilities

It has been long established that patients in long-term care facilities can carry vancomycin-resistant Enterococcus (VRE) at high rates. VRE is also a reservoir of vancomycin resistance for other pathogens, such as methicillin-resistant Staphylococcus aureus. Therefore, preventing VRE colonization is an important step in preventing the rise of additional multidrug resistant organisms.

Previous research has not typically, however, differentiated between vancomycin-resistant Enterococcus faecium and Enterococcus faecalis, despite their potential for divergent epidemiologic characteristics.

A new study published in Open Forum Infectious Diseases explored the differential epidemiology of vancomycin-resistant E faecium and E faecalis colonization in nursing facilities, finding E faecium is carried longer and more strongly associated with device use compared with E faecalis.

The investigators conducted their research at 6 different nursing facilities in Southeastern Michigan, with enrollment taking place between November 2013 and May 2016. Any nursing facility patient recently admitted and not receiving end of life care was eligible.

A total of 651 patients were enrolled into the study. Microbiological samples were collected to assess multidrug-resistant organism colonization on the day of enrollment, day 14, day 30, and monthly for up to 6 months. Species typing was conducted via duplex polymerase chain reaction.

The average age of participants was 74.7 years (standard deviation (SD): 12.2). Men made up 42.2% of participants. In total, 62.4% of participants were white and 37.3% were black.

At time of enrollment, 192 (29.5%) of participants already tested positive for 1 or both species of VRE. Of those participants, 116 (17.8%) were colonized with E faecium and 55 (8.4%) were colonized with E faecalis.

During the overall study period, 1 or both species of VRE were isolated from 265 (40.7%) of 651 participants. Incidence rates were similar for both species, but E faecium was carried for twice as long as E faecalis at 69 and 32 days, respectively.

“The observation of a longer duration of E faecium carriage, 69 days, compared to 32 for E faecalis, is novel…The shorter duration of carriage for E faecalis coupled with the similar incidence rates suggests E faecalis may be more transmissible: new cases are being acquired at a similar rate but is cleared from the host more rapidly,” study authors wrote.

Among the 441 participants that were considered at risk for at least 1 species who completed follow-up visits, 109 were found to be newly colonized during the 6 months of follow-up.

Individuals with antibiotic use in the past 30 days had a greater incidence of both species, but device use was most strongly associated with incidence of E faecium.

“Minimizing duration of device use and following good hygiene practices while inserting, maintaining, and removing devices, would likely reduce [vancomycin-resistant] E faecium colonization, and that of other pathogenic organisms,” study authors concluded.