One-year monitorization of the gut colonization by multidrug resistant bacteria in elderly of a single long-term care facility.

Objective: To monitor the gut colonization by multidrug resistant (MDR) bacteria in residents of a single long-term care facility (LTCF) in relation to their clinical evolution, antibiotic consumption and mortality risk.

Methods: In a total of 187 voluntarily enrolled residents, five rectal swabs samples were recovered over 1 year. Selective media were used to isolate MDR bacteria. Clinical data related to infections, antibiotic consumption and mortality were recovered. Mortality risk among residents who were MDR colonized and non-colonized was compared by Kaplan-Meier curves.

Results: Globally, 25% of residents have gut colonization by ESBL-producing Escherichia coli with a lack of other pathogens such as Acinetobacter baumannii or Clostridioides difficile. Monitoring of ESBL-producing E. coli colonization for 1 year allowed to us to establish three categories among residents: 48.6% never colonized, 15.5% had a persistent colonization, and the remaining 35.8% presented intermittent colonization. The rates of mortality, infections and antibiotic exposure were comparable among ESBL-producing E. coli colonized and non-colonized residents, except for the intermittent colonization group in which a higher and statistically significant mortality rate was observed. As expected, urinary and respiratory tract infections were the most prevalent infectious pathologies in the LTCF, with amoxicillin/clavulanate and fluoroquinolones being the most prescribed antibiotics. A high percentage of ESBL-producing E. coli (28%), and fluoroquinolone resistance were detected in clinical samples.

Conclusions: The monitoring of gut colonization by MDR microorganisms in a single LTCF for 1 year demonstrated the predominance of ESBL-producing E. coli. Almost half of the residents were resistant to its colonization, whereas in 15.5% of them gut colonization was stable. Incidence of infectious episodes and antibiotic exposure were comparable between colonized and non-colonized subjects, but the group with the highest risk of mortality was that with intermittent colonization by ESBL-producing E. coli.