These findings contribute to conclusively clarifying why, among S. pyogenes isolates with the M phenotype, the tetracycline- resistant ones are, as a rule, SmaI typeable, while the tetracycline-susceptible ones are not. Previous studies have shown that, while the two related genetic elements (Tn1207.3 and 10394.4) typical of tetracycline-susceptible isolates are inserted into the same prophage, the tet(O)-mef(A) element typical of tetracycline-resistant isolates is inserted into a different prophage (6). The present results show that the R-M cassette encoding, in Tn1207.3-10394.4, the methyltransferase responsible for DNA resistance to cleavage by SmaI is absent in the tet(O)-mef(A) element where, together with an adjacent ORF, it is replaced by three new ORFs flanked, both upstream and downstream, by homologous regions.

SmaI typeability and tetracycline susceptibility/resistance in Streptococcus pyogenes isolates with efflux-mediated erythromycin resistance / Bacciaglia, Alessandro; Brenciani, Andrea; Varaldo, Pietro; Giovanetti, Eleonora. - In: ANTIMICROBIAL AGENTS AND CHEMOTHERAPY. - ISSN 0066-4804. - 51:(2007), pp. 3042-3043. [10.1128/AAC.00249-07]

SmaI typeability and tetracycline susceptibility/resistance in Streptococcus pyogenes isolates with efflux-mediated erythromycin resistance.

BACCIAGLIA, ALESSANDRO;BRENCIANI, Andrea;VARALDO, Pietro;GIOVANETTI, Eleonora
2007-01-01

Abstract

These findings contribute to conclusively clarifying why, among S. pyogenes isolates with the M phenotype, the tetracycline- resistant ones are, as a rule, SmaI typeable, while the tetracycline-susceptible ones are not. Previous studies have shown that, while the two related genetic elements (Tn1207.3 and 10394.4) typical of tetracycline-susceptible isolates are inserted into the same prophage, the tet(O)-mef(A) element typical of tetracycline-resistant isolates is inserted into a different prophage (6). The present results show that the R-M cassette encoding, in Tn1207.3-10394.4, the methyltransferase responsible for DNA resistance to cleavage by SmaI is absent in the tet(O)-mef(A) element where, together with an adjacent ORF, it is replaced by three new ORFs flanked, both upstream and downstream, by homologous regions.
2007
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11566/50844
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