Meticillin-resistant Staphylococcus aureus transmission among healthcare workers, patients and the environment in a large acute hospital under non-outbreak conditions investigated using whole-genome sequencing

Source avec lien : Journal of Hospital Infection, (Prépublication). 10.1016/j.jhin.2021.08.020

L’objectif de cette étude était d’étudier les événements de transmission (TE) impliquant les travailleurs de la santé, les patients et l’environnement dans des conditions non épidémiques dans un hôpital avec un historique de SARM endémique en utilisant le séquençage du génome entier (WGS).

Background The role of MRSA colonization of healthcare workers (HCWs), patients and the hospital environment in MRSA transmission in non-outbreak settings is poorly understood. Aims To investigate transmission events (TEs) involving HCWs, patients and the environment under non-outbreak conditions in a hospital with a history of endemic MRSA using whole-genome sequencing (WGS). Methods HCW (N=326) and patient (N=388) volunteers on nine wards were tested for nasal and oral MRSA colonization over two years. Near-patient environment (N=1,164), high-frequency touch sites (N=810) and air (N=445) samples were screened for MRSA. Representative MRSA and clinical isolates were analysed by WGS and core-genome multilocus sequence typing (cgMLST). Closely-related isolates (≤24 allelic differences) were segregated into related isolated groups (RIGs). Findings In total 155 MRSA were recovered: clinical isolates (N=41), HCWs (N=22), patients (N=37), environmental isolates (N=55). Nine clonal complexes (CCs) were identified among 110/155 MRSA sequenced with 77/110 assigned to CC22. Seventy-nine MRSA segregated into 17 RIGs. Numerous potential TEs were associated with CC22-MRSA (RIGs 1-15), CC45-MRSA (RIG-16) and CC8-MRSA (RIG-17). RIG-1, (the largest RIG) contained 24 ST22-MRSA-IVh from six HCWs, six patients, four clinical and eight environmental samples recovered over 17-months involving 7/9 wards. TEs involving HCW-to-patient, HCW-to-HCW, patient-to-patient and environmental contamination by HCW/patient isolates were evident. HCW, patient, clinical and environmental isolates were identified in four, nine, seven and 13 RIGs, respectively, with 12 /13 of these containing isolates closely-related to HCW and/or patient isolates. Conclusions WGS detected numerous potential hospital MRSA TEs involving HCWs, patients and the environment under non-outbreak conditions.

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