Occurrence and diversity of genetic resistance determinants among Enterobacteriaceae clinical isolates in Aveiro, Portugal

Abstract number: 1733_524

Ferreira S., Toleman M., Walsh T., Mendo S.

Objectives: The aim of the present study was to assess the occurrence of antimicrobial resistance determinants and their genetic apparatus among clinical isolates from Aveiro, Portugal.

Methods: The isolates population was composed by Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Providencia stuartii, Stenotrophomonas maltophilia, Citrobacter freundii, Enterobacter cloacae, Enterobacter aerogenes, Morganella morganii and Proteus mirabilis. PCR, sequencing and sequence analysis was used to assess b-lactamase encoding sequences, class 1 and class 2 integrases, integron variable regions and ISCR elements. The Biological Sequence Alignment Editor, BioEdit version 7.0.0 was used for DNA and amino acid sequence alignments. Sequences obtained were compared with others deposited in the EMBL Genebank.

Results: PCR specific for CTX-M encoding sequence showed the presence of this gene in 33.3% of the isolates bearing an ESBL. The intI1 gene was present in 20.7% of the Enterobacteriaceae isolates. The intI2 gene was present in 3 isolates possessing the same cassette array (dfrA1, sat1, aadA1). A total of 14 cassettes included in 6 different cassette arrays were identified – the most frequently found genes were aadA variants. The ISCR elements were present in 8.1% of the isolates and were present in 9 E. coli strains and 1 Enterobacter cloacae.

Conclusion: This is the first report of ISCR elements from Portugal and as they are intrinsically linked to antibiotic resistant genes, their high incidence, particularly among E. coli strains, is disconcerting. The high percentage of CTX-M genes confirms that these have now become the dominant ESBL genotype within this region.