High prevalence of the arginine catabolic mobile element in carriage isolates of methicillin-resistant Staphylococcus epidermidis.
BACKGROUND
the arginine catabolic mobile element (ACME) associated with staphylococcal cassette chromosome mec (SCCmec) in the USA300 clone of community-acquired methicillin-resistant Staphylococcus aureus enhances its fitness and ability to colonize the host. Staphylococcus epidermidis may act as a reservoir of ACME for S. aureus. We assessed the diffusion of ACME in methicillin-resistant S. epidermidis (MRSE) isolates colonizing outpatients.


METHODS
seventy-eight MRSE strains isolated in outpatients from five countries were characterized by multilocus sequence typing (MLST) and SCCmec typing and screened for the arcA and opp3AB markers of ACME. ACME-arcA and ACME-opp3AB were sequenced. ACME type I from MRSE and USA300 were compared by long-range PCR (LR-PCR).


RESULTS
fifty-three (67.9%) MRSE strains carried an ACME element, including 19 (24.4%), 32 (41.0%) and 2 (2.6%) with ACME type I (arcA+/opp3AB+), II (arcA+/opp3AB-) and III (arcA-/opp3AB+), respectively. The prevalence of ACME did not differ between clonal complex 2 (42/60 strains) and other sequence types (11/18 strains, P = 0.7), with MLST data suggesting frequent intraspecies acquisition. ACME-arcA sequences were highly conserved, whereas ACME-opp3AB displayed 11 distinct allotypes. ACME was found in 14/29, 9/11 and 30/37 strains with type IV, type V and non-typeable SCCmec, respectively (P = 0.01). ACME was more frequently associated with ccrC than with ccrAB2 (82.4% versus 60.0%, P = 0.048). LR-PCR indicated structural homologies of ACME I between MRSE and USA300.


CONCLUSIONS
ACME is widely disseminated in MRSE strains colonizing outpatients and may contribute to their spread in a community environment with low antibiotic exposure, as suggested for USA300.
Bacteriology Unit and National Reference Center for Emergence of Resistance in Commensal Flora, Bichat-Claude Bernard Hospital (Assistance Publique-Hôpitaux de Paris), Paris, France.
François
F
Barbier
David
D
Lebeaux
David
D
Hernandez
Anne-Sophie
AS
Delannoy
Valérie
V
Caro
Patrice
P
François
Jacques
J
Schrenzel
Etienne
E
Ruppé
Kevin
K
Gaillard
Michel
M
Wolff
Sylvain
S
Brisse
Antoine
A
Andremont
Raymond
R
Ruimy
D001120:Arginine / Q000378:metabolism*; D015373:Bacterial Typing Techniques; D002353:Carrier State / Q000382:microbiology*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005838:Genotype; D006801:Humans; D020071:Interspersed Repetitive Sequences; D016106:Methicillin Resistance; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010045:Outpatients; D016133:Polymerase Chain Reaction; D015995:Prevalence; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
D004269:DNA, Bacterial; D001120:Arginine