Replicon typing of plasmids carrying the sul3-atypical integrons among Salmonella isolates

Abstract number: P2020

Antunes P., Novais A., Coque T.M., Peixe L.

Objectives: The spread of atypical sul3-integron platforms containing three different gene cassette arrays has been recently detected among Salmonella isolates from Portugal. The aim of this study was to characterize the plasmids associated with these genetic elements in a large collection of Portuguese Salmonella isolates.

Methods: Fifty-two representative isolates carrying sul3-atypical integrons (n = 22) and class 1 integrons (n = 30) from different sources (human, food products and environment), serotypes and PFGE-clones were studied. Plasmid analysis included determination of size (Barton's method), comparison of RFLP patterns and characterisation of incompatibility groups by rep-PCR typing method and further hybridisation.

Results: Plasmids belonging to different Inc groups were identified. Those carrying sul3 type I-integrons (5'CS-dfrA12-orfF-aada2-cmlA1-aadA1-qacH-tnpA-sul3-tnp) were diverse and classify as IncI1 (conjugative, 100 Kb, in 2 clones, 2 serotypes), IncN (non-transferable, 135 Kb, n= 1 strain) and FIIA (transferable, 100–165 Kb, 2 clones of 2 serotypes), a common replicon among Salmonella virulence plasmids. Plasmids carrying the sul3 type II-integrons (5'CS-dfrA12-orfF-aadA2/1-qacH-tnpA-sul3-tnp), only described in the MDR S. Rissen clone, did not amplify with rep primers we used (70 Kb). The sul3 type III-integrons (5'CS-estX-psp-aadA2-cmlA1-aadA1-qacH-tnpA-sul3-tnp) were located in non-transferable IncA/C plasmids, (150, 170 and 220 Kb) of S. Typhimurium DT104, or in a conjugative IncHI1 plasmid (240 Kb) of a non-DT104 S. Typhimurium isolate. IncFII plasmids were detected in several isolates carrying class 1 integrons, but the majority of these isolates were negative by rep-PCR method.

Conclusion: The atypical sul3-integron platforms are located within plasmids of different Inc plasmid groups, some of them restricted to specific clones, and mostly not related to those carrying class 1 integrons in Salmonella.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
Back to top