Colonization of long-term care facility residents in three Italian Provinces by multidrug-resistant bacteria

Elisabetta Nucleo, Mariasofia Caltagirone, Vittoria Mattioni Marchetti, Roberto D’Angelo, Elena Fogato, Massimo Confalonieri, Camilla Reboli, Albert March, Ferisa Sleghel, Gertrud Soelva, Elisabetta Pagani, Richard Aschbacher, Roberta Migliavacca, Laura Pagani

Rationale and aims of the study were to compare colonization frequencies with MDR bacteria isolated from LTCF residents in three different Northern Italian regions, to investigate risk factors for colonization and the genotypic characteristics of isolates. The screening includedEnterobacteriaceaeexpressing extended-spectrum β-lactamases (ESβLs) and high-level AmpC cephalosporinases, carbapenemase-producingEnterobacteriaceae,Pseudomonas aeruginosaorAcinetobacter baumannii, methicillin-resistantStaphylococcus aureus(MRSA) and vancomycin-resistant enterococci (VRE). Urine samples and rectal, inguinal, oropharyngeal and nasal swabs were plated on selective agar; resistance genes were sought by PCR and sequencing. Demographic and clinical data were collected. Among the LTCF residents, 75.0% (78/104), 69.4% (84/121) and 66.1% (76/115) were colonized with at least one of the target organisms in LTCFs located in Milan, Piacenza and Bolzano, respectively. ESβL producers (60.5, 66.1 and 53.0%) were highly predominant, mainly belonging toEscherichia coliexpressing CTX-M group-1 enzymes. Carbapenemase-producing enterobacteria were found in 7.6, 0.0 and 1.6% of residents; carbapemenase-producingP. aeruginosaandA. baumanniiwere also detected. Colonization by MRSA (24.0, 5.7 and 14.8%) and VRE (20.2, 0.8 and 0.8%) was highly variable. Several risk factors for colonization by ESβL-producingEnterobacteriaceaeand MRSA were found and compared among LTCFs in the three Provinces. Colonization differences among the enrolled LTCFs can be partially explained by variation in risk factors, resident populations and staff/resident ratios, applied hygiene measures and especially the local antibiotic resistance epidemiology. The widespread diffusion of MDR bacteria in LTCFs within three Italian Provinces confirms that LTCFs are an important reservoir of MDR organisms in Italy and suggests that future efforts should focus on MDR screening, improved implementation of infection control strategies and antibiotic stewardship programs targeting the complex aspects of LTCFs.