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Volume 7, Number 2—April 2001
4th Decennial International Conference on Nosocomial and Healthcare-Associated Infections


The Changing Epidemiology of Staphylococcus aureus?

Henry F. ChambersComments to Author 
Author affiliation: University of California San Francisco and San Francisco General Hospital, San Francisco, California, USA

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Table 4

Elements found within three types of mec-associated DNA

mec types
Genetic featurea I II III
Size 32 kb 52 kb 60 kb
mecA + + +
mecR1-mecI - + +
ccrAB + + +
pUB110 - + -
IS431 (number) 1 2 4
Tn554 (number) 0 1 2
Tc, Hg resistance - - +

amecA = gene encoding PBP 2a, the penicillin-binding protein with low binding affinity that mediates methicillin resistance; mecR1-mecI = sensor-transducer and repressor genes that regulate production of inducible PBP 2a; ccrAB = cassette chromosome recombinases A and B that mobilize the mec element; pUB110 = integrated plasmid that encodes tobramycin and kanamycin resistance; IS431 = insertion sequence; Tn554 = erythromycin-resistance encoding transposon; Tc = tetracycline-resistance determinant; Hg = mercury-resistance determinant.

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