PFGE diversity within the methicillin-resistant Staphylococcus aureus clonal lineage ST398.
BACKGROUND
Livestock has recently been identified as a new reservoir of methicillin-resistant Staphylococcus aureus (MRSA). Most isolates belong to ST398 and are non-typeable with PFGE using SmaI, making it difficult to study transmission and outbreaks. Therefore, a new PFGE using Cfr9I, a neoschizomer of SmaI was optimized and evaluated to investigate ST398 isolates.


RESULTS
After optimizing and evaluating the Cfr9I PFGE, clear and reproducible banding patterns were obtained from all previously non-typeable MRSA (NT(SmaI) -MRSA) isolates. The PFGE patterns of ST398 isolates showed more diversity than with spa-typing and/or MLST. The PFGE results showed diversity within and between the two most prevalent spa-types of NT(SmaI) -MRSA (t011 and t108). No match was found, when comparing banding patterns of the NT(SmaI) -MRSA with 700 different PFGE types, obtained with SmaI digestion, in our database of more than 4000 strains. Furthermore, possible transmission among veterinarians and their family members was investigated and an outbreak of ST398 MRSA in a residential care facility was confirmed with the Cfr9I PFGE.


CONCLUSIONS
The adjusted PFGE can be used as a method for selecting important and distinct ST398 isolates for further research. The adjustments in the PFGE protocol using Cfr9I are easy to implement to study the ST398 clonal lineage in laboratories which already have a PFGE facility.
Centre for infectious disease control, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands. thijs.bosch@rivm.nl
Thijs
T
Bosch
Albert J
AJ
de Neeling
Leo M
LM
Schouls
Kim W
KW
van der Zwaluw
Jan A J W
JA
Kluytmans
Hajo
H
Grundmann
Xander W
XW
Huijsdens
D004269:DNA, Bacterial / Q000032:analysis; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry / Q000378:metabolism; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods*; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D015203:Reproducibility of Results; D013203:Staphylococcal Infections / Q000382:microbiology*; D013205:Staphylococcal Protein A / Q000235:genetics
D004269:DNA, Bacterial; D013205:Staphylococcal Protein A; C025651:CCCGGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific