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Characterisation of community and hospital-associated Staphylococcus aureus isolates in Southampton

Abstract number: P1416

Green S., Marsh P., Ahmad N., Jeffries J., Clarke S.

Objectives: Meticillin-sensitive S.aureus (MSSA) can acquire the meticillin resistance determinant mecA, in a mobile genetic element known as the staphylococcal cassette chromosome-mec (SCCmec), giving rise to meticillin resistant S.aureus (MRSA). Community-associated (CA)-MRSA strains appear to contain the smaller, more mobile versions of the cassette such as SCCmec IV and V, and some strains may produce Panton-Valentine leukocidin (PVL). We used molecular typing to characterise hospital (HA) and community-associated (CA) S.aureus isolates circulating in Southampton, UK and to investigate the spread of PVL and SCCmec types IV and V.

Methods: We examined 71 CA and HA-MRSA/MSSA isolates (Southampton General Hospital in-patients and patients recently admitted or community healthcentre attendees). Isolates were typed by pulsed-field gel electrophoresis (PFGE), sequence types (STs) identified by multi-locus sequence typing and PCR used to determine SCCmec type and detect lukFS for PVL.

Results: Fifteen PVL positive isolates were identified, ten of which were MRSA that contained SCCmec IV. Seven of these were ST 30. Of the fifteen PVL positive strains, seven were community-associated, four of which were MRSA. Predominant STs were 22 and 30. Amongst ST 22 (n = 38), 12 were confirmed as MRSA, all were PVL negative, and 15 were hospital-associated. Amongst ST 30 (n = 3), 7 were confirmed as MRSA, all of which were PVL positive, and 5 of which were hospital-associated. The predominant PFGE type was EMRSA-15 and related subtypes. For both ST 22 and 30, there was no correlation between site of acquisition and meticillin-resistance.

Conclusions: Our studies reveal the presence of the mobile mecA-determinant SCCmec IV in CA- and HA-MRSA isolates some of which are also PVL positive. SCCmec V was present in two HA-MRSA isolates. The additional presence of PVL positive MSSA in community and hospital-derived isolates suggests a risk of gene transfer from SCCmec IV MRSA to PVL positive MSSA.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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