TABLE 1.

Characteristics of the sul3-producing Salmonella isolates used in this study

Integron type, serotype (no. of isolates)PFGEbSourcec (no. of isolates)Isolation: yr/location (no. of isolates)Resistance phenotyped and gene profileIntegron size (bp) and/or gene cassette (5′CS-3′CS)fSize(s) (kb)e of plasmid(s) carrying-sul3-associated integrons (no. of isolates)
I
    Rissen (2)NS (1), U (1)2002 (1), 2004 (1)/north (1), south (1)Strr Chlr Tetr Sulr Tmpr aadA2-aadA1 cmlA1 tetA sul3 dfrA12int1100 (2)
    Typhimurium (7)QH (6), S (1)2000 (1), 2003 (2), 2004 (4)/north (7)Chlr Sulr Tmpr (Strr Kanr Tetr) cmlA1 sul3 dfrA12 (aadA2-aadA1 aphA1 tetBint1100 (1), 160 (1), 165 (1)
    IIIb:65:lv:enxz15 (1)SH (1)2003 (1)/south (1)Strr Chlr Sulr Tmpr aadA2-aadA1 cmlA1 sul3 dfrA12int1100 (1)
    Haifa (1)ZH (1)2004 (1)/north (1)Strr Ampr Chlr Tetr Sulr Tmpr aadA2-aadA1 blaTEM cmlA1 tetA sul2-sul3 dfrA12int1165 (1)
    Typhimurium DT104 (1)aAU (1)2004 (1)/north (1)Strr Ampr Chlr Tetr Sulr Tmpr aadA2-aadA1 blaTEM cmlA1 tetA sul1 sul3 dfrA121,000; aadA2135 (1)
II
    Rissen (3)NS (3)2002 (2), 2003 (1)/ north (3)Strr Ampr Tetr Sulr Tmpr aadA2-aadA2/1 blaTEM tetA sul1-sul3 dfrA122,000; dfrA12 orfF aadA270 (2)
III
    Typhimurium (1)JS (1)2003 (1)/south (1)Strr Kanr Ampr Chlr Tetr Sulr Tmpr aadA2-aadA1 aphA1 blaTEM cmlA1-catA tetB sul1-sul3 dfrA11,700; dfrA1 aadA1240 (1)
    Typhimurium DT104 (2)aXH (2)2004 (2)/south (2)Strr Genr Ampr Chlr Tetr Sulr Tmpr aadA2-aadA1 aac(3)-IV blaTEM cmlA1 tetA sul1-sul2-sul3 dfrA122,000; dfrA12 orfF aadA2220 (1)
    Typhimurium DT104 (29)aOH (17), S (4), P (1), C (2), U (1), E (3), UN (1)2000 (1), 2002 (3), 2003 (12), 2004 (13)/north (19), center (1), south (8), UN (1)Strr Chlr Sulr (Genr Kanr Ampr Tetr Tmpr Nalr) aadA2-aadA1 cmlA1 sul1-sul2-sul3 [floR aac(3)-IV blaTEM tetA tetB dfrA12]2,000; dfrA12 orfF aadA2150 (1), 170 (5), 220 (3), 150 + 170 (1)
  • a PCR assay for the identification of S. enterica serotype Typhimurium DT104 and U302 phage types (15) positive.

  • b Clones are designated by capital letters as previously described (2).

  • c H, humans; S, pork products; P, poultry products; C, beef products; U, unknown food product; E, environment; UN, unknown source.

  • d Antibiotic resistances and resistance genes transferred to transconjugants are underlined. Variable antibiotic resistance and resistance gene among isolates of the same PFGE are in parentheses. The following genes implicated in antimicrobial resistance were detected by PCR (1, 2, 9): blaPSE-1, blaOXA-30, and blaTEM encoding β-lactam resistance; floR, cmlA1, and catA encoding chloramphenicol resistance; tetA, tetB and tetG encoding tetracycline resistance; sul1, sul2 and sul3 encoding sulfonamide resistance; aac(3)-IV and aphA1 encoding, respectively, gentamicin and kanamycin resistance. The characterization of genes associated with streptomycin (aadA) and trimethoprim (dfrA) resistance was done by PCR amplification and DNA sequencing in isolates carrying those genes inserted into integrons, as described previously (2). Antimicrobial agents were tested as previously described (2).Abbreviations: Strr, streptomycin resistance; Genr, gentamicin resistance; Kanr, kanamycin resistance; Ampr, ampicillin resistance; Nalr, nalidixic acid resistance; Chlr, chloramphenicol resistance; Tetr, tetracycline resistance; Sulr, sulfamethoxazole resistance; Tmpr, trimethoprim resistance.

  • e Plasmid profiles obtained by S1 PFGE in the isolates selected for testing; the plasmids transferred to transconjugants are underlined.

  • f int1 gene was detected, as previously described (2) in isolates without a positive 5′CS-3′CS PCR assay.