was identified in 17 isolates (19%) (online Appendix Table).
Strains with phenotypes lacking resistance to [greater than or equal to] 1 of the antimicrobial agents (ACSSuT) typical for SGI1 were further investigated for the presence of SGI1 variants.
Most DT104 and DT104b isolates displayed the phenotype ACSSuT (Table 1), which is compatible with the possession of SGI1; 122 (84%) of the 146 strains were resistant to ACSSuT with or without additional antimicrobial drug resistance that is regarded as independent of the SGI1 (e.
Detection of SGI 1-related genes and regions by PCR showed that the ACSSuT isolates were positive in all PCRs as expected for SGI1 (Table 2), whereas the 3 ASu isolates were positive for the left/right junction, but only 1 integron and pse-1 and qac/sull, in accordance with the phenotype and the SGI1-B variant, were positive (3,12).
Paratyphi B dT+ (ApCmSmSpSuTc phenotype) containing SGI1 that causes severe disease in humans, particularly young children.
Age, y/Sex SGI1 ([paragraph]) Set 1 SRC229 <1/F + SRC230 1/M + SRC231 -- + Set 2 SRC232# 11/F + SRC233# 11/F + SRC233A -- ND Set 3 SRC145 74/F + SRC142 -- + SRC143 -- + Set 4 SRC149 12/M + SRC147 -- + SRC148 -- + Control SRC50 14/M + ** * All isolates were resistant to ampicillin, chloramphenicol, streptomycin, spectinomycin, sulfonamides, and tetracycline.
2-kb integrons and gave a PCR product for the left junction amplification reaction but not the right junction, which suggests that a portion of SGI1 downstream of the integrons was missing.
The three strains that did not cluster with the other ACSSuT strains did not harbor SGI1 as described above.
The antibiotic resistance gene cluster represents approximately one third of SGI1 and is located at the 3' end of the structure (6,7).
Recently, SGI1 has also been identified in other serovar Typhimurium phage types (i.
We examined this isolate to determine the presence of SGI1.
The serotype Paratyphi B strain showed a multidrug-resistance profile typical of serotype Typhimurium DT 104 or serotype Agona strains carrying SGI1, i.