Typing of plasmids of multi-resistant E.coli producing or not extended-spectrum lactamases using two different assays: replicon typing and relaxase detection

Abstract number: P1724

Ruiz del Castillo B., Alvarado García A., Garcillán-Barcia M., de la Cruz F., Martínez-Martínez L.

Background: Classification of epidemiologically-relevant plasmids is currently based in the detection of plasmid replication and partition regions, leading to their grouping in incompatibility (Inc) groups. Plasmids conferring antibiotic-resistance are mainly transmissible. They have been recently classified in six MOB families according to the evolutionary relationships or their relaxase, a key protein in the transfer process. Here we have accomplished the identification of plasmids in a multiresistant E. coli collection from clinical isolates. Two classification approaches have been used: the classical PCR-based replicon typing and MOB identification. Results allowed us to compare the efficiency and specificity of both methods and to depict the nature of the plasmids involved in the multiresistant phenotype of the isolates.

Methods and Results: Transconjugants (Tc) were obtained from 19/20 ESBL and 13/20 non-ESBL isolates. Plasmid DNA from donor and Tc were extracted and characterized by replicon typing and MOB identification using a set of degenerate primers specific for each relaxase family. In the multiresistant, non-ESBL collection, the most prevalent group was IncF (12/13), followed by IncI1 (7/13). Members of the groups IncB/O (3/13), K (1/13), A/C (3/13), and Pa (1/13) were also present. Relaxase detection confirmed these results: MOBF12 (12/13), MOBP12 (8/12), MOBH12 (3/12), MOBP11 (1/13). Cryptic mobilizable MOBQ plasmids without Inc group assigned and IncX plasmids, both missed by the replicon typing method, were also found by MOB amplification. In the ESBL collection, MOBP12 plasmids were the most abundant, being present in all isolates. They cluster members of IncI1 (7/19), IncK (14/19) and IncB/O (12/19) groups. MOBF12 plasmids were the second most prevalent (17/19), while 18/19 were found to belong to the F group (FIA, FIB, Frep) by replicon-typing. Also MOBP11 (IncPa plasmids), MOBQ and MOBC12 (both omitted in the replicon typing) were observed in 2/19, 3/19 and 3/19 isolates, respectively.

Conclusions: Our collection contains transmissible plasmids of different incompatibility groups. MOB detection and replicon typing are complementary methods for classifying plasmids in clinical isolates of E. coli. The first one is especially useful for classifying plasmids that harbour multiple replicons and those without Inc group assigned. The use of combined methods provides higher accuracy and more information about the plasmid backbone.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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