Molecular epidemiology of Staphylococcus epidermidis in
prosthetic joint infections
av
Emeli Månsson
Akademisk avhandling
Avhandling för medicine doktorsexamen i medicinsk vetenskap, inriktning medicin,
som kommer att försvaras offentligt fredag den 6 december 2019 kl. 09.00, HSC1, Campus USÖ, Örebro universitet
Opponent: professor Kåre Bergh Avdelningen för klinisk och molekylär medicin,
Norges teknisk-naturvitenskapelige universitet Trondheim, Norge
Örebro universitet
Institutionen för medicinska vetenskaper 701 82 ÖREBRO
Abstract
Emeli Månsson (2019): Molecular epidemiology of Staphylococcus
epidermidis in prosthetic joint infections. Örebro Studies in Medicine 203. Staphylococcus epidermidis is ubiquitous in the human microbiota, but
also an important pathogen in healthcare-associated infections, such as prosthetic joint infections (PJIs). In this thesis, aspects of the molecular epidemiology of S. epidermidis in PJIs were investigated with the aim of improving our understanding of the pre- and perioperative measures required to reduce the incidence of S. epidermidis PJIs.
In Paper I, S. epidermidis retrieved from air sampling in the operating field during arthroplasty was characterized by multilocus sequence typ-ing and antibiotic susceptibility testtyp-ing. No isolates belongtyp-ing to se-quence types (STs) 2 and 215, previously associated with PJIs, were found in the air of the operating field. During air sampling, several
Staphylococcus pettenkoferi isolates were identified, and as a spin-off of
Paper I, the genomic relatedness of these isolates to S. pettenkoferi iso-lates from blood cultures was described in Paper II.
In Paper III, genetic traits distinguishing S. epidermidis isolated from PJIs were determined using genome-wide association study accounting for population effects after whole-genome sequencing (WGS) of a popu-lation-based 10-year collection of S. epidermidis isolates from PJIs and of nasal isolates retrieved from patients scheduled for arthroplasty. Genes associated with antimicrobial agents used for prophylaxis in ar-throplasty, i.e., beta-lactam antibiotics, aminoglycosides, and chlorhexi-dine, were associated with PJI origin. S. epidermidis from PJIs were dominated by the ST2a, ST2b, ST5, and ST215 lineages.
In Paper IV, selective agar plates were used to investigate colonization with methicillin resistant S. epidermidis (MRSE) in patients scheduled for arthroplasty. MRSE were further characterized by WGS. A subset of patients was found to harbour PJI-associated S. epidermidis lineages in their microbiota before hospitalization, but no isolates belonging to the ST2a lineage nor any rifampicin-resistant isolates were retrieved.
Keywords: Staphylococcus epidermidis, molecular epidemiology, prosthetic
joint infections, whole genome sequencing, Staphylococcus pettenkoferi Emeli Månsson, School of Medical Sciences, Örebro University, SE-70182 Örebro, Sweden, emeli.mansson@regionvastmanland.se
