Salmonella enterica serovar typhimurium bla(PER-1)-carrying plasmid pSTI1 encodes an extended-spectrum aminoglycoside 6'-N-acetyltransferase of type Ib


Casin I., Hanau-Bercot B., Podglajen I., Vahaboglu H., Collatz E.

ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, cilt.47, sa.2, ss.697-703, 2003 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 47 Sayı: 2
  • Basım Tarihi: 2003
  • Doi Numarası: 10.1128/aac.47.2.697-703.2003
  • Dergi Adı: ANTIMICROBIAL AGENTS AND CHEMOTHERAPY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.697-703
  • Kocaeli Üniversitesi Adresli: Hayır

Özet

We have studied the aminoglycoside resistance gene, which confers high levels of resistance to both amikacin and gentamicin, that is carried by plasmid pSTI1 in the PER-1 beta-lactamase-producing strain of Salmonella enterica serovar Typhimurium previously isolated in Turkey. This gene, called aac(6')-Ib(11), was found in a class I integron and codes for a protein of 188 amino acids, a fusion product between the N-terminal moiety (8 amino acids) of the signal peptide of the beta-lactamase OXA-1 and the acetyltransferase. The gene lacked a plausible Shine-Dalgarno (SD) sequence and was located 45 nucleotides downstream from a small open reading frame, ORF-18, with a coding capacity of 18 amino acids and a properly spaced SD sequence likely to direct the initiation of aac(6')-Ib(11) translation. AAC(6')-Ib(11), had Leu118 and Ser119 as opposed to Gin and Leu or Gin and Ser, respectively, which were observed in all previously described enzymes of this type. We have evaluated the effect of Leu or Gin at position 118 by site-directed mutagenesis of aac(6')-Ib(11) and two other acetyltransferase gene variants, aac(6')-Ib(7) and -Ib(8), which naturally encode Gln118. Our results show that the combination of Leu118 and Ser119 confers an extended-spectrum aminoglycoside resistance, with the MICs of all aminoglycosides in clinical use, including gentamicin, being two to eight times higher for strains with Leu118 and Ser119 than for those with Gln118 and Ser119.