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Volume 14, Number 11—November 2008

Research

Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus, Rural Southwestern Alaska1

Michael Z. DavidComments to Author , Karen M. Rudolph, Thomas W. Hennessy, Susan Boyle-Vavra, and Robert S. Daum
Author affiliations: University of Chicago, Chicago, Illinois, USA (M.Z. David, S. Boyle-Vavra, R.S. Daum); Centers for Disease Control and Prevention, Anchorage, Alaska, USA (K.M. Rudolph, T.W. Hennessy);

Main Article

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.

Main Article

1Portions of this study were presented at the 47th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy, September 17–20, 2007, Chicago, IL, USA.

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