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

Abstract

Background: The role of meticillin-resistant Staphylococcus aureus (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 ¼ 326) and patient (N ¼ 388) volunteers on nine wards were tested for nasal and oral MRSA colonization over two years. Near-patient environment (N ¼ 1164), high-frequency touch sites (N ¼ 810) and air (N ¼ 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 ¼ 41), HCWs (N ¼ 22), patients (N ¼ 37), environmental isolates (N ¼ 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 1e15), 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

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

“…17/ 01). HCWs and ward patients were recruited subject to previously described inclusion criteria and with informed consent [3,5]. Previous nasal MRSA or MSSA colonization status of participants was unknown to the researchers.…”

“…Isolate recovery was described previously [3,5]. Briefly, participant samples were taken from the anterior nares using sterile transport swabs, and taken from the oral cavity using a phosphate-buffered saline rinse [3,5,8].…”

“…Isolate recovery was described previously [3,5]. Briefly, participant samples were taken from the anterior nares using sterile transport swabs, and taken from the oral cavity using a phosphate-buffered saline rinse [3,5,8]. Environmental sampling was undertaken in parallel with participant sampling to provide a snapshot of the MSSA environmental burden.…”

“…The authors recently investigated the transmission dynamics of MRSA under non-outbreak conditions in nine wards of a large acute hospital in Dublin, Ireland with a history of endemic MRSA over 2 years using whole-genome sequencing (WGS) [5]. The study focused on potential TEs between HCWs, patients and near-patient environments (NPEs), extended ward environments, and the air.…”

“…The study focused on potential TEs between HCWs, patients and near-patient environments (NPEs), extended ward environments, and the air. Numerous potential HCW-to-patient, HCW-to-HCW and patient-to-patient TEs, and environmental contamination by HCW/patient strains, were identified involving MRSA from multiple multi-locus sequence typing (MLST) clonal complexes (CCs) clustered into related isolate groups (RIGs) determined by core genome (cg)MLST [5]. Isolates within individual RIGs were closely related and exhibited 24 cgMLST allelic differences.…”