Spread of E. coli and Enterobacteriaceae S275 contaminated chicken is an unlikely continuing source for current human gut colonisation with this type. E. coli with CTX-M-2 were isolated from 2/2 and 5/10 chicken meat samples originating from the Netherlands and Brazil, respectively; CTX- M-2 is the most common CTX-M type from clinical E. coli in Brazil but is rare in clinical disease in the UK, although it has been isolated from faecal samples. CTX-M-14 is the second commonest UK isolate and common in other EU countries. Analysis was complicated by the fact that countries of origin of 40 raw chicken samples was not identifiable on packaging, however, it was apparent that there may be significant differences in the CTX-M enzyme found in chicken originating from different countries. Our findings suggest that chicken meat may be a potential source of bowel colonisation with E. coli producing CTX-M enzymes, but do not identify a link to the main CTX-M type (CTX-M-15) from clinical infections in the UK. P1026 Occurrence and diversity of genetic resistance determinants among Enterobacteriaceae clinical isolates in Aveiro, Portugal S. Ferreira, M. Toleman, T. Walsh, S. Mendo (Aveiro, PT; Cardiff, UK) 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 stuar- tii, 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. P1027 Plasmid-mediated AmpC b-lactamases in Enterobacteri- aceae lacking a chromosomal ampC gene and E. coli : preva- lence at a Swiss university hospital and distribution of the different molecular types in the northern part of Switzerland H. Adler, L. Fenner, D. Hohler, R. Frei (Basle, CH) Objectives: (1) to determine the prevalence of plasmid-mediated AmpC b-lactamases in isolates of Enterobacteriaceae lacking a chromosomal ampC gene and E. coli at the University Hospital Basel. (2) to determine which types of plasmid-mediated AmpC b-lactamases occur in the northern part of Switzerland. Methods: Between January 27 and September 27, 2006, a total of 2,100 consecutive clinical isolates of E. coli and Enterobacteriaceae naturally lacking a chromosomal ampC gene were screened for resistance to cefoxitin with the disk diffusion test. Furthermore, clinical isolates suspected to harbour a plasmid-mediated AmpC b-lactamase were collected from laboratories in the northern part of Switzerland. Multiplex AmpC PCR (Perez-Perez and Hanson, 2002, J Clin Microbiol 40: 2153-62) was performed on all cefoxitin-resistant isolates. The ampC genes of the PCR-positive isolates were sequenced. Results: (1) One hundred of the consecutive clinical isolates were cefoxitin-resistant. Plasmid mediated AmpC b-lactamases were found in three isolates of E. coli. Thus, the prevalence of plasmid-mediated AmpC b-lactamases was 0.14%. (2) Plasmid-mediated AmpC b-lactamases were found in 16 isolates from 5 laboratories in the northerm part of Switzerland. Thirteen of the isolates were E. coli, 2 were Klebsiella pneumoniae and one was Proteus mirabilis. CMY-2 and CMY-2 like AmpC b-lactamases were detected in 11 isolates of E. coli, 2 isolates of K. pneumoniae and one isolate of P. mirabilis. DHA-1 was detected in 2 isolates of E. coli. Conclusion: (1) The prevalence of 0.14% of plasmid-mediated AmpC b-lactamases in Enterobacteriaceae lacking a chromosomal ampC-gene plus E. coli at the University Hospital Basel is very low. (2) CMY-2 and CMY-2 like AmpC b-lactamases are the predominant plasmid-mediated AmpC b-lactamases (87.5%) in the northern part of Switzerland. DHA-1 was the only other AmpC b-lactamase that was found (12.5%). P1028 Countrywide spread of CTX-M-3 and CTX-M-15 extended-spectrum b-lactamases among Enterobacteriaceae in Bulgaria R. Markovska, I. Schneider, E. Keuleyan, M. Sredkova, D. Ivanova, K. Rachkova, B. Markova, T. Kostyanev, E. Savov, I. Mitov, A. Bauernfeind (Sofia, BG; Munich, DE; Pleven, Stara Zagora, BG) Objectives: (1) To characterise the distribution of CTX-M producing isolates among eight clinical centres from three towns in Bulgaria. (2) To investigate their epidemiology and mechanism of spread. Methods: Antibiotic susceptibility was determined by disc diffusion method (CLSI standards 2005). The extended-spectrum b-lactamase (ESBL) production was confirmed by CLSI double disc ESBL confirmatory method. Conjugation was performed on solid medium. Isoelectric focusing, followed by bioassay, ESBL-group specific PCR and sequencing of ESBL genes of representative isolates were carried out. RAPD with ERIC-1A and ERIC-2 primers and plasmid fingerprinting with PstI restriction were performed with representative strains. Results: During a survey on ESBLs in Bulgaria from 1996 to 2003, CTX-M-type ESBL-producing Klebsiella spp. (47), E. coli (113), S. marcescens (9), Enterobacter. (5), C. freundii (6) from eight centres in three different towns were detected. The most widespread enzyme was CTX-M-15 (in all centres), followed by CTX-M-3 (in six centres). CTX- M-15 was produced mainly from E. coli strains (83%) and associated with urinary tract infections (49%). CTX-M-3 was produced from K. pneumoniae – in 52%. The rate of CTX-M enzyme harbouring strains has increased rapidly after first detection in 2001 to 56% in 2003. Resistance of CTX-M-3 producing strains was: AUG – 39%, TOB – 89%, GEN – 100%, AMI – 87%, CIP – 0%, TET – 33%, SXT – 85% and CHL – 26%. For CTX-M-15 producers the resistance was: AUG – 87%, TOB – 95%, GEN – 88%, CIP – 84%, TET – 94%, SXT – 52% and CHL – 51%. Epidemiological analysis by RAPD revealed a broader diversity of RAPD-types among CTX-M-3 producing strains in comparison with CTX-M-15 producers. The PstI plasmid fingerprinting showed a broader variety of CTX-M-15 encoding plasmids than CTX-M-3 harbouring plasmids. One of CTX-M-3 carrying plasmid was dominant, we detected it in four different bacterial species, isolated from patients in three towns. Conclusions: In eight clinical centres in three Bulgarian towns CTX-M- 15 and CTX-M-3 were the only CTX-M-type b-lactamases found. Our data suggest that plasmid transfer is the main mechanism of CTX-M-3 spread, while for CTX-M-15 producers spread by clonal dissemination is more prevalent.