Dynamics of colonization in patients with health care-associated infections at step-down care units from a tertiary care hospital in Mexico

Background: Patient colonization has been suggested as a risk factor in hospital-associated infections (HAI) development, which are of the most frequent complications in hospitals. Objective: To examine the colonization process and possible transmission routes of HAI-causative agents in step-down care unit (SDCU) patients. Methods: Patients admitted to SDCU within 48 hours of admission that had no evidence of infection present, nurse health care workers (HCWs), and relatives of infected patients were included. Participants were sampled and cultured at different times in different body surfaces. Environmental surfaces and medical devices were also sampled. Antimicrobial susceptibility and clonal relatedness were determined in selected HAI-causative agents, environmental, nurse HCWs, and patient isolates. Results: A total of 2,735 isolates corresponding to 126 species were identified. Of the 11 patients included, 8 developed 1-3 HAls (14 isolates recovered as HAI-causative agents). Acinetobacter baumannii (36% of infections) was distributed in clone A (n = 1), B (n = 3), and F (n = 1); Klebsiella pneumoniae (29%) in clones A (n = 2) and B (n =1) and Enterobacter cloacae (7%) in one clone A. Causative agents were progressively recovered from environmental surfaces and medical devices before and after HAI onset. Conclusions: Highly related strains were recovered from environmental surfaces, patients, and nurse HCWs before and after HAI outcome. This is a first step to examine colonization process in SDCU settings and provides a base for further studies to understand colonization dynamics and the role of patients' relatives and nurse HCWs in organism transmission in the SDCU. (C) 2020 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.