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2011 OMIG Abstract 5

Prevalence of Staphylococcal Cassette Chromosome mec (SCCmec Cassette) types and
Panton-Valentine Leukocidin (PVL) toxin among Staphylococcus aureus isolates

J. Maestre, E.C. Alfonso, E. Perez, M. Diaz, D. Miller
Department of Ophthalmology, Bascom Palmer Eye Institute, Miami, FL

Purpose: To determine the presence of SCCmec types and PVL toxin among ocular Staphylococcus aureus isolates.

Methods: A multiplex PCR assay with seven primer sets was used to characterize SCCmec (I-IV) types among nonrandom Staphylococcus aureus (N=123, MRSA-82 and MSSA-41) collected within the last five years. Separate PCR assays were run to confirm the presence of the mecA gene and detect the PVL gene locus. SCCmec types and PVL genes were correlated with isolate origin (community vs. healthcare), ocular source and presence of fluoroquinolone resistance.

Results: Both healthcare-acquired (HA-MRSA) SCCmec types (I, II, III, N=35, 28.4%) and community-acquired (CA-MRSA, N=32, 60.4%, IV) were documented among these MRSA isolates. The PVL toxin was documented in 63 (51.2%) of the 123 total isolates, SCCmec type (V, N=1, 1.2%). Among the MRSA isolates, PVL toxin was most frequently associated with SCCmec type IV (71.4%, 30/42), followed by SCCmec type II (24.2%, 8/33). The PVL gene was documented in 21/41 (51.2%) of the MSSA isolates. Ocular sources included conjunctiva (43%, N=53), lids (13.8%, N=17), cornea (10.5%, N=13), lacrimal sac (9.7%, N=12), IOF (2.4%, 3) and other ocular, NOS (12.2%, N=15). Community-acquired SCCmec type IV was most commonly associated with conjunctiva (N=18, 42.8%) and lids (N=10, 23.8%) isolates. The six MRSA cornea isolates were SCCmec II. 88.5% of SCCmec types (I-III) were resistant to ciprofloxacin vs. 61.9% for SCCmec type IV. Results for moxifloxacin resistance were 80% and 40.5%, respectively.

Conclusions: The predominant profile for ocular MRSA isolates among this group was SCCmec IV (CA-MRSA) harboring the necrotizing PVL toxin gene with high level fluoroquinolone resistance. Understanding the source and profile of ocular MRSA can aid in therapeutic management and infection prevention strategies.

Disclosure: N

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