National surveillance of Staphylococcus epidermidis recovered from bloodstream infections in Belgian hospitals.
The objectives of this study were: (i) to determine the species diversity of CoNS isolated from bloodstream infections collected during a national surveillance study; and (ii) to examine the antimicrobial resistance and genomic diversity among Staphylococcus epidermidis isolates.



Eighty CoNS were identified by MALDI-TOF. Antimicrobial resistance determination, molecular characterization of resistance and virulence genes, and molecular typing were performed for S. epidermidis isolates.



The majority (76%) of CoNS were identified as S. epidermidis. Among these S. epidermidis, 77% were resistant to methicillin [methicillin-resistant S. epidermidis (MRSE)] and showed multiresistance to other antimicrobials. Genes implicated in resistance were erm(C), erm(A) and msr(A) for erythromycin, aacA-aphD and aadC for aminoglycosides, tet(K) for tetracycline and mupA for high-level resistance to mupirocin. Molecular typing showed that 34/40 MRSE isolates (85%) belonged to clonal complex (CC) 2 that could be subdivided into CC2-I (ST2) and CC2-II (ST5, ST59 and ST88). In contrast, methicillin-susceptible S. epidermidis displayed high genomic diversity. The majority (70%) of S. epidermidis isolates contained an icaA or arcA gene. The icaA gene was found in the CC2-I subgroup, whereas arcA was more common in methicillin-susceptible S. epidermidis.



S. epidermidis was frequently recovered among CoNS isolated from bloodstream infections with a high proportion of MRSE being multiresistant. A large number of S. epidermidis belonged to CC2, a clone that is disseminated worldwide. More studies are needed to understand its clonal evolutionary success.
National Reference Centre for Staphylococcus aureus, Laboratory of Microbiology - Université Libre de Bruxelles (ULB), Brussels, Belgium ariane.deplano@erasme.ulb.ac.be.
Ariane
A
Deplano
National Reference Centre for Staphylococcus aureus, Laboratory of Microbiology - Université Libre de Bruxelles (ULB), Brussels, Belgium.
Stien
S
Vandendriessche
National Reference Centre for Staphylococcus aureus, Laboratory of Microbiology - Université Libre de Bruxelles (ULB), Brussels, Belgium.
Claire
C
Nonhoff
National Reference Centre for Staphylococcus aureus, Laboratory of Microbiology - Université Libre de Bruxelles (ULB), Brussels, Belgium.
Magali
M
Dodémont
National Reference Centre for Staphylococcus aureus, Laboratory of Microbiology - Université Libre de Bruxelles (ULB), Brussels, Belgium.
Sandrine
S
Roisin
National Reference Centre for Staphylococcus aureus, Laboratory of Microbiology - Université Libre de Bruxelles (ULB), Brussels, Belgium.
Olivier
O
Denis
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology*; D001530:Belgium / Q000453:epidemiology; D018441:Biofilms / Q000187:drug effects; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D014644:Genetic Variation; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008712:Methicillin / Q000494:pharmacology; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D058885:Multilocus Sequence Typing; D011159:Population Surveillance; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D014774:Virulence / Q000187:drug effects
D000900:Anti-Bacterial Agents; D008712:Methicillin