Volume 14, Number 11—November 2008
Research
Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus, Rural Southwestern Alaska1
, Karen M. Rudolph, Thomas W. Hennessy, Susan Boyle-Vavra, and Robert S. Daum
Table 1
Selected characteristics of MRSA isolates from southwestern Alaska, 1997, 2000, and 2004–2006*
| Characteristic | Retrospective collection, no. (%) | Prospective collection, no. (%) |
|---|---|---|
| Drug susceptibility | n = 36 |
n = 120 |
| Ciprofloxacin | 36 (100) | 112 (93.3) |
| Clindamycin, total† | 14 (39) | 51 (42.5) |
| Single-agent testing | 33 (92) | 51 (42.5) |
| D-test negative | 3/22 (14) | NA |
| Erythromycin | 11 (31) | 48 (40.0) |
| Gentamicin | 35 (97) | 115 (95.8) |
| Rifampin | 36 (100) | 117 (97.5) |
| Vancomycin | 36 (100) | 120 (100) |
| Trimethoprim-sulfamethoxazole | 35 (97) | 120 (100) |
| Resistance to >2 non–β-lactam antimicrobial drug classes |
21 (58) |
69 (58) |
| PVL genes present | n = 36 |
n = 42 |
| Yes | 33 (92) | 42 (100) |
| No |
3 (8) |
0 |
| SCCmec type IV |
36 (100) |
42 (100) |
| MLST CC type | ||
| CC1 | 22 (63) | 35 (83) |
| ST1 | 20 (57) | 35 (83) |
| ST1slv‡ | 1 (3) | 0 |
| ST474 | 1 (3) | 0 |
| CC8 | 0 | 3 (7) |
| ST8 | 0 | 3 (7) |
| CC30 | 11 (32) | 4 (10) |
| ST30 | 9 (26) | 4 (10) |
| ST484 | 1 (3) | 0 |
| ST535 | 1 (3) | 0 |
| CC59 | 2 (6) | 0 |
| ST59 | 1 (3) | 0 |
| ST59slv‡ | 1 (3) | 0 |
*MRSA, methicillin-resistant Staphylococcus aureus; NA, not applicable; PVL, Panton-Valentine leukocidin; SCCmec, staphylococcal chromosomal cassette mec; MLST, multilocus sequence typing; CC, clonal complex; ST, sequence type.
†Indicates clindamycin susceptibility by single-agent testing and negative D-test results. D-tests for inducible clindamycin resistance were not indicated for any isolates from the prospective collection and were performed for 22 isolates in the retrospective collection.
‡slv, single-locus variant by MLST testing.
1Portions of this study were presented at the 47th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy, September 17–20, 2007, Chicago, IL, USA.