Abstract
Purpose:
MRSA among ocular isolates continue to increase in frequency and morbidity. Rapid Molecular characterization provides information on origin, distribution, therapeutic choices and transmission. We evaluated the DiversiLab rep-PCR Microbial typing system as a rapid method for documenting the molecular profiles and clonality of ocular MRSA strains to provide a better understanding of ocular MRSA epidemiology and transmission.
Methods:
We compared the use of multiplex PCR with the commercial DiversLab (DL) to identify and discriminate between SCCmec types among 56 MRSA isolates from 6 ocular sources (cornea, N=23, conj or lids, N=14, lacrimal sac, N=10, socket, N=5, vitreous-N=4). Similarity index (% agreement) and feasibility of using the DL system for spa typing and clonality (origin) of ocular MRSA isolates were documented against 2 well characterized, standard ATCC MRSA research panels organized by SCCmec and or PFGE types
Results:
: Concordance of SCCmec types of the two systems was 64.3%. Distribution of SCCmec types via multiplex PCR was: Type II (MRSA-HA), 64.3%,Type IV (MRSA-CA), 23.2% Type V, 3.6% Nontypable, 8.9%, DL profiles included: Type I (MRSA-HA), 16.1%, Type II, 35.7%, Type III (MRSA-CA), 8.9%, Type IV, 35.7% and Nontypable, 3.6%. The greatest discord was for SCCmec type II. Type II isolates were more frequently recovered from lacrimal sac 90% and cornea- 65% cultures. Type IV was most frequently recovered from conj/lids/socket 57.9%. DL divided ocular isolates into 5 clonal complexes, CC8 (41.1%)-which houses epidemic MRSA (EMRSA) community strains, CC5 (30.3%)-housing USA100-the most common healthcare associated-MRSA strain in the US, CC30 (19.6%)-USA200 and EMRSA 16-second most common MRSA-HA strain, CC22 (5.3%)-EMRSA-15 and-CC80 (3.6%)-an emerging ocular MRSA strain. The 5 sequence types (ST), ST5, ST254, ST228, ST30 and ST247 ranged from 8.9% (ST247) to 25% (ST5). Agreement with the standard ATCC panels was 87.5% (7/8).
Conclusions:
Ocular MRSA have diverse clonal origins and may be site specific. The DiversiLab provides a rapid, method for screening ocular MRSA, determining evolutionary origins and documenting the emergence of unique MRSA strains.
Keywords: 593 microbial pathogenesis: clinical studies •
433 bacterial disease •
535 gene microarray