Population Dynamics of Staphylococcus aureus in Cystic Fibrosis Patients To Determine Transmission Events by Use of Whole-Genome Sequencing

摘要

Staphylococcus aureus colonization in populations with chronic illness can often lead to repeated infections and severe disease. Patients with the genetic disease cystic fibrosis (CF) are especially vulnerable due to the very nature of their illness, in which thick mucus in the airways provides for an enriched environment suited to bacterial survival and colonization while allowing for evasion of host immune defenses (1, 2). S. aureus is known to be one of the first pathogens to colonize CF lungs with a 69% prevalence rate, peaking at ages 11 to 15 (3). S. aureus is typically isolated first from the upper airways of CF patients, and in many cases, colonization of the lower airways follows (3, 4). Repeated or chronic antibiotic usage that is common in the CF population may influence colonization by disturbing the normal upper respiratory microbiome, allowing S. aureus to invade and persist. Once colonization is established in the lungs, eradication efforts are typically unsuccessful and single-strain persistence is thought to occur (5, 6), with only a small percentage of colonized CF patients showing evidence of strain replacement (7). Unfortunately, there is an upward trend toward acquisition of methicillin-resistant strains (methicillin-resistant Staphylococcus aureus [MRSA]), with prevalence increasing from 12% in 2003 to 26% in 2013 (8, 29). MRSA colonization is associated with poorer health outcomes in CF patients than colonization with methicillin-sensitive S. aureus (MSSA) (9, 10).