Extended-Spectrum β-Lactamase- and Carbapenemase-Producing Enterobacterales Intestinal Carriage Among Outpatients: Microbiological and Epidemiological Differences Between Private Dwelling Residents and Nursing Home Residents.

The aim of this work was to assess the prevalence of carbapenemase-producing and extended-spectrum β-lactamase-producing Enterobacterales (ESBLPE) intestinal carriage among private dwelling residents (PDR) and nursing home residents (NHR) from the catchment area of Hospital Verge de la Cinta (Tortosa. North-Eastern Spain), and to depict clinicoepidemiological features of colonized individuals. Prevalence of ESBLPE carriage amid 762 PDR (0-94 years) who had feces collected for routine culture was 7.3% and 31% among 71 NHR (68-98 years) screened upon hospital admission. The mean age of colonized and noncolonized subjects was 30 and 32.8 years in PDR (p = 0.58) and 85 and 87 years in NHR (p = 0.32). The predominant ESBLPE was CTX-M-15-producing Escherichia coli (42.8% in PDR and 68.2% in NHR [25% and 86.7% belonging to O25b-ST131 clone; p < 0.0001]), followed by CTX-M-9-group- and SHV-producing E. coli and by CTX-M-15-producing Klebsiella pneumoniae. Overall, 72.7% of ESBLPE were multidrug resistant and 46.2% carried transferable quinolone determinants. Institutionalization in a nursing home was a risk factor for ESBLPE and extended-spectrum β-lactamase (ESBL)-producing O25b-ST131 E. coli carriage in individuals over 67 years (odds ratio 7.7 and 14.1). Previous antibiotic use and skin ulcers were significantly associated with ESBLPE carriage in NHR. Age <25 years in PDR and amoxicillin/clavulanate exposure in NHR protected against ESBL-producing O25b-ST131 E. coli colonization. Only two PDR, with known risk factors, bore OXA-48-producing isolates. These results highlight the role of nonhospitalized intestinal carriers, particularly NHR, as ESBLPE reservoirs and the preponderance of CTX-M-15, mainly linked to O25b-ST131 clone, as well as the emergence of carbapenemase-producing Enterobacterales carriers.