Demonstration of Plasmid-Mediated Drug Resistance in

Plasmid-mediated kanamycin resistance was detected in a strain ofMycobacterium abscessus subsp. bolletii responsible for a nationwide epidemic of surgical infections in Brazil. The plasmid did not influence susceptibility to tobramycin, streptomycin, trimethoprim-sulfamethoxazole, clarithromycin, or ciprofloxacin. Plasmid-mediated drug resistance has not been described so far in mycobacteria. Plasmid-mediated drug resistance is uncommon in mycobac-teria. A 56,267-bp circular plasmid of the broad-host-range IncP-1 subgroup was detected in a strain of Mycobacterium ab-scessus subsp. bolletii (formerly known as Mycobacterium massil-iense [1] andMycobacterium abscessus subsp.massiliense [2]) that was responsible for a nationwide outbreak of mycobacterial sur-gical infections in Brazil in 2004 to 2008 (3, 4). This plasmid, named pMAB01, contains a complete system for conjugative DNA transfer and two genetic load regions carrying antimicrobial resistance genes, including the Tn5393c streptomycin resistance (str) transposon and a typical class 1 integron with an incorpo-rated gene cassette encoding an aminoglycoside 6=-N-acetyltrans-ferase (aac[6=]-Ib), the dihydropteroate synthase type 1 gene (sul1), and a conserved open reading frame (orf5) that carries a GCN5-likeN-acetyltransferase (3). We investigated the contribu-tion of this plasmid to antimicrobial drug resistance inM. absces-sus and in Escherichia coli