Epidemiology of plasmid-mediated quinolone resistance in salmonella enterica serovar typhimurium isolates from food-producing animals in Japan

A total of 225 isolates of Salmonella enterica serovar Typhimurium from food-producing animals collected between 2003 and 2007 were examined for the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants, namely qnrA, qnrB, qnrC, qnrD, qnrS, qepA and aac(6')Ib-cr, in Japan. Two isolates (0.8%) of S. Typhimurium DT104 from different dairy cows on a single farm in 2006 and 2007 were found to have qnrS1 on a plasmid of approximately 9.6-kbp. None of the S. Typhimurium isolates had qnrA, qnrB, qnrC, qnrD, qepA and acc(6')-Ib-cr. Currently in Japan, the prevalence of the PMQR genes among S. Typhimurium isolates from food animals may remain low or restricted. The PFGE profile of two S. Typhimurium DT104 isolates without qnrS1 on the farm in 2005 had an identical PFGE profile to those of two S. Typhimurium DT104 isolates with qnrS1. The PFGE analysis suggested that the already existing S. Typhimurium DT104 on the farm fortuitously acquired the qnrS1 plasmid

Phylogenetic groups and cephalosporin resistance genes of Escherichia coli from diseased food-producing animals in Japan

A total of 318 Escherichia coli isolates obtained from different food-producing animals affected with colibacillosis between 2001 and 2006 were subjected to phylogenetic analysis: 72 bovine isolates, 89 poultry isolates and 157 porcine isolates. Overall, the phylogenetic group A was predominant in isolates from cattle (36/72, 50%) and pigs (101/157, 64.3%) whereas groups A (44/89, 49.4%) and D (40/89, 44.9%) were predominant in isolates from poultry. In addition, group B2 was not found among diseased food-producing animals except for a poultry isolate. Thus, the phylogenetic group distribution of E. coli from diseased animals was different by animal species. Among the 318 isolates, cefazolin resistance (minimum inhibitory concentrations: ≥32 μg/ml) was found in six bovine isolates, 29 poultry isolates and three porcine isolates. Of them, 11 isolates (nine from poultry and two from cattle) produced extended spectrum β-lactamase (ESBL). The two bovine isolates produced blaCTX-M-2, while the nine poultry isolates produced blaCTX-M-25 (4), blaSHV-2 (3), blaCTX-M-15 (1) and blaCTX-M-2 (1). Thus, our results showed that several types of ESBL were identified and three types of β-lactamase (SHV-2, CTX-M-25 and CTX-M-15) were observed for the first time in E. coli from diseased animals in Japan

Protection against Pasteurella multocida conferred by an intranasal fowl cholera vaccine in Khaki Campbell ducks

Fowl cholera affects the poultry farming including ducks. The commercial fowl cholera vaccines using parenteral administration are available. Recently, an intranasal fowl cholera vaccines have been developed and tested in layers. This study, we analyzed the biological function of recombinant outer membrane protein H (rOmpH) of Pasteurella multocida strain X-73 and its antiserum. In addition, we also evaluated the protective efficacy in Khaki Campbell ducks. An adhesion inhibition assay on duck embryo fibroblast (DEF) cells was performed demonstrating that rOmpH-immunized duck sera had a potential inhibitory effect on adhesion ability of bacterial strain. An intranasal fowl cholera vaccine was formulated containing 100 μg rOmpH and 3 μg E. coli enterotoxin B (LTB) as an adjuvant. Ducks were intranasally immunized three times at three-week intervals. Challenge exposure was conducted by inoculation at 3.5 × 103 CFU/ml of a strain of X-73 at four weeks after the last immunization. Sera IgY and secretory IgA antibody titers were significantly increased (P ＜ 0.05) post immunization. Lymphocytes from ducks immunized with the rOmpH-LTB-based intranasal vaccine showed higher proliferative response to P. multocida antigens than those from ducks immunized with only rOmpH or LTB (P ＜ 0.05). Protection conferred by immunization with an intranasal or bacterin vaccine in ducks against challenge-exposure were 90% and 80%, respectively. We conclude that the intranasal fowl cholera vaccine protected ducks from artificial P. multocida infection. However, the rOmpH will be formulated with the commercial adjuvant and will be conducted against more P. multocida field strains in the duck flocks