IAFP 2009 Program Book and Abstract Book - AB178

P3-80 Antimicrobial Resistance in Escherichia coli O157:H7 from Patients in Alberta SHEILA M. COOK, Christina J. Ferrato, Bryanne Crago, Melissa St. Denis, Linda Chui, Stanford Kim, Tim McAllister, Ranjana Sharma, Rafiq Ahmed and Marie Louie Provinical Laboratory for Public Health (Microbiology), Calgary, AB, Canada Introduction: The use of antibiotics in animals and agriculture may select for antimicrobial resistance (AMR) in Escherichia coli O157:H7. Consumption of AMR bacteria can lead to colonization of the human gastrointestinal tract. Although E. coli O157:H7 infections are not clinically treated with antibiotics, horizontal transfer of resistance genes to susceptible commensal flora can occur and can have serious implications. Purpose: This study was undertaken to determine trends in AMR and assesses strain clonality through phage typing (PT) and pulsed-field gel electrophoresis (PFGE) among E. coli O157:H7 isolates associated with human disease. Methods: E. coli O157:H7 isolates (n = 430) from human origin were isolated by the Alberta Provincial Laboratory for Public Health (APLPH). Sporadic cases and single representative isolates from each outbreak in 2003 to 2006 were subtyped by PFGE at APLPH and PT at the Canadian National Microbiology Laboratory. AMR profiling was obtained using microbroth dilution testing with 15 antimicrobial agents. Results: Of the 430 E. coli O157:H7 isolates, 39 (9.1%) were resistant to at least one antibiotic and 26 (6.0%) were resistant to two or more antibiotics, while the most frequent resistance was to sulfisoxazole (5.3%), tetracycline (4.9%), and chloramphenicol (3.3%). All of the AMR E. coli O157:H7 strains typed as having unique PT and PFGE patterns. An increase in nalidixic acid resistance was observed from 1.0% in 2004 to 3.4% in 2006, and these isolates were limited to two PTs. Significance: Overall AMR among E. coli O157:H7 strains associated with human disease collected between 2003 and 2006 was not common and resistant strains demonstrated no clonality by PT or PFGE. This suggests that the risk of transferring AMR to commensal gut flora was low; however, multi-drug resistance and resistance to nalidixic acid was observed, suggesting that emerging AMR trends should be monitored over time. P3-81 Pediocin PA-1-like Bacteriocin Produced by Enterococcus faecium ST5HA Svetoslav D. Todorov, MARIA TERESA DESTRO, Eb Chiarini, Bernadette D. Franco, Mariza Landgraf and Manuela Vaz-Velho University of São Paulo, Food and Experimental Nutrition, São Paulo, Brazil Introduction: Bacteriocins of lactic acid bacteria (LAB) are ribosomally synthesized antimicrobial peptides. Their bactericidal mechanisms may include pore formation, degradation of cellular DNA, disruption through specific cleavage of 16S rDNA, and inhibition of peptidoglycan synthesis. Purpose: This research is on isolation of an anti-Listeria bacteriocin producing strain, characterization of the genetic determinants of bacteriocin production, and study of some aspects of the bacteriocin mode of action. Methods: The bacteriocin-producing strain ST5HA was isolated from smoked salmon and identified on the basis of API50CHL, PCR with genus-specific-primers and sequencing of the 16s rDNA. The homology of the produced bacteriocin ST5HA to pediocin PA-1 was determined with PCR and sequencing of the amplified product. Results: Enterococcus faecium ST5HA produces a pediocin-like bacteriocin with activity against several LAB, Listeria spp., and some other human and food pathogens. Bacteriocin ST5HA was produced at high levels in MRS broth at 30°C and 37°C and reached maximum production (1.0 × 109 AU/ml against Listeria ivanovii subsp. ivanovii ATCC19119) after 43 h. Its molecular mass, 4.5kDa, was determined by tricine-SDS-PAGE. Addition of bacteriocin ST5HA to a 3-h-old culture of L. ivanovii subsp. ivanovii ATCC19119 inhibited growth for 24 h. Strain ST5HA contains a 1044 bp DNA fragment corresponding in size to that recorded for pediocin PA-1. The combined application of low levels (below MIC) of ciprofloxacin and bacteriocin ST5HA results in a synergetic effect in the inhibition of L. ivanovii subsp. ivanovii ATCC19119. Significance: To our knowledge, this is first report on E. faecium ST5HA as a potential producer of the chromosomally associated pediocin PA-1-like bacteriocin, based on the high similarity to the sequence of pedB. Bacteriocin ST5HA is highly active against L. ivanovii subsp. ivanovii ATCC19119 and exhibits a synergetic effect in the inhibition of this test microorganism when applied with sublethal doses of ciprofloxacin. P3-82 Effect of Carnobacterium maltaromaticum UAL 307 and Enteroccocus faecalis 710C Cultures and Culture DSC Supernatants on the Growth of Listeria monocytogenes in Fresh Beef Sausage EMEFA A. MONU, Kamila Moquin and Lynn M. McMullen University of Alberta, Agricultural, Food and Nutritional Science, Edmonton, AB, Canada Introduction: Bacteriocins are inhibitory compounds produced by several bacteria, including Carnobacterium maltaromaticum and Enterococcus faecalis and inhibit the growth of Listeria monocytogenes in meat products. Recent studies have shown the potential of C. maltaromaticum to enhance the color stability of fresh meat. Purpose: The purpose of this study was to use bacteriocin-producing lactic acid bacteria and their culture supernatant to inhibit the growth of L. monocytogenes in fresh beef sausage and determine the effect of C. maltaromaticum on sausage color stability. Methods: Lean ground beef was used to make fresh sausage in collagen casings, which were inoculated (except for a control treatment) with a cocktail of L. monocytogenes and C. maltaromaticum UAL 307 at approximately 104 CFU/g and 105 CFU/g, respectively, combined with the supernatants of C. maltaromaticum UAL 307 or E. faecalis 710C. Sausages were packaged either aerobically or in an atmosphere of 30% CO2 + 0.4% CO and stored at 4°C for up to 10 or 15 days. The growth of L. monocytogenes and sausage pH and color were measured either every two days (aerobic storage) or every three days (anaerobic storage). Results: Sausages containing C. maltaromaticum UAL 307 with either of the supernatants eliminated L. monocytogenes after 8 days of aerobic storage and 12 days of anaerobic storage; addition of C. maltaromaticum UAL 307 alone resulted 178 — Abstract Book Poster

IAFP 2009 Program Book and Abstract Book

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