Distribution of the ACME-arcA gene among methicillin-resistant Staphylococcus aureus from England and Wales.
BACKGROUND
The ST8-SCCmecIVa (USA300) methicillin-resistant Staphylococcus aureus (MRSA) clone can harbour the arginine catabolic mobile element (ACME). The arc gene cluster within the ACME may function as a virulence or strain survival factor. We determined the distribution of the ACME-associated arcA gene among genetically diverse MRSA from around England and Wales.


METHODS
MRSA isolates (n = 203) of diverse genetic types, referred to the England and Wales Staphylococcus reference laboratory, were tested for the presence of the ACME-arcA gene. ACME-arcA-positive isolates were characterized by toxin gene profiling, PFGE and spa sequence typing. MICs of a range of antimicrobials were also determined.


RESULTS
The ACME-arcA gene was detected in 17 isolates. Twelve were related to known ST8-MRSA-SCCmecIVa isolates of the USA300 lineage by pulsotype and were resistant to oxacillin, with variable ciprofloxacin and erythromycin resistance. Outside the USA300 lineage, four of the remaining five ACME-arcA isolates were closely related ST97-MRSA-SCCmecV, Panton-Valentine leucocidin (PVL)-negative, resistant to oxacillin and variously resistant to erythromycin, ciprofloxacin, clindamycin, gentamicin, tetracycline and fusidic acid. The remaining isolate was ST1, PVL-positive and resistant to fusidic acid as well as oxacillin. Thirteen out of the 17 isolates were associated with skin and soft tissue infections.


CONCLUSIONS
The detection of ACME-arcA in diverse MRSA types highlights the mobility of the elements encoding ACME-arcA genes. The diversity of strain types and resistance profiles among ACME-arcA-encoding MRSA is a cause for public-health concern and demands continued surveillance and close monitoring.
Ellington
Matthew J
MJ
Staphylococcus Reference Laboratory (SRL), Laboratory of Healthcare Associated Infection, Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK. matthew.ellington@hpa.org.uk
Yearwood
Lianne
L
Ganner
Mark
M
East
Claire
C
Kearns
Angela M
AM
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001120:Arginine / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics; D001483:Base Sequence; D016521:Electrophoresis, Gel, Pulsed-Field; D004739:England / Q000453:epidemiology; D006801:Humans; D006867:Hydrolases / Q000235:genetics*; D016106:Methicillin Resistance / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D014774:Virulence; D014852:Wales / Q000453:epidemiology
D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D001120:Arginine; D006867:Hydrolases; C019723:arginine deiminase