High frequency of colonization by extended-spectrum beta-lactamase-producing Gram-negative bacilli in hemodialysis patients and their household contacts: dissemination between community and hospital

Abstract

Objectives: Increase in colonization by beta-lactam-resistant Gram-negative bacilli (BR-GNB) represent a risk for infections and bacterial resistance spread, not only in hospitals but community. Hemodialysis patients and their household contacts transit constantly between the two environments. This study aims to determine the clinical and epidemiological characteristics of BR-GNB colonization in hemodialysis patients and their household contacts, as well as the genetic relationship between their isolates.Methods: A cross-sectional study was conducted on hemodialysis patients from hospital-associated dialysis center in Medellín-Colombia, and their household contacts. Clinical and epidemiological information was collected. Colonization was assessed from stool or rectal swab samples. Bacterial identification and susceptibility were determined using chromogenic media and Vitek-2. Molecular characterization included beta-lactamase detection by PCR, MLST, PFGE, and identification of E. coli phylogroups by Clermont protocol.Results: This study included thirty-six hemodialysis patients and 90 of their household contacts. Colonization by BR-GNB occurred in 58.3% of patients and 22.2% of household contacts. The main beta-lactamase detected was CTX-M group-1 (40.5%). In three of the nine homes that had more than one colonized individual, a genetic relationship was found. MLST showed a high diversity in E. coli isolates, and the most frequent phylogroups were B1 and B2. Conclusions: These results show a high frequency of colonization in our population, and the presence of potentially pathogenic BR-GBN not only in hospitals but in the community. This highlights the importance of populations in transit between the two environments, and the need to prevent the spread of bacterial resistance outside hospitals.