The presence of class 1 integrons was investigated in 156 epidemiologically unrelated Salmonella Typhimurium isolates. Of these 156 isolates, 70 were of definitive phage type DT104 and 86 were strains of various phage type, RDNC and untypable, designated here as non-DT104 strains. Integrons were found in 47 of DT104 isolates (67.1%), while in all strains with characteristic pentaresistance (R-type ACSSuT) two integrons 1.0 kb and 1.2 kb in size were found. Among 86 non-DT104 strains, integrons with sizes of 1.6 kb and 1.9 kb in four multidrug-resistant strains DT193 and U302 were found. The integrons from selected strains were further sequenced and the aadA1, aadA2, dhfr1, dhfr12 and bla(PSE) genes were found embedded in cassettes.

2002-12-01·Journal of Clinical Microbiology2区 · 医学

Multiple Genetic Typing of Salmonella enterica Serotype Typhimurium Isolates of Different Phage Types (DT104, U302, DT204b, and DT49) from Animals and Humans in England, Wales, and Northern Ireland

2区 · 医学

Article

作者: Liebana, Ernesto ; Threlfall, E. John ; Lindsay, Elisabeth ; Garcia-Migura, Lourdes ; McDowell, Stanley W. J. ; Davies, Robert H. ; Clifton-Hadley, Felicity A. ; Clouting, Carol

ABSTRACTSalmonella enterica serotype Typhimurium is a common cause of salmonellosis among humans and animals in England, Wales, and Northern Ireland. Phage types DT104 and U302 were the most prevalent types in both livestock and humans in 2001. In addition, Salmonella serotype Typhimurium DT204b was responsible for a recent international outbreak involving England. A total of 119 isolates from humans ( n = 28) and animals or their environment ( n = 91), belonging to DT104 ( n = 66), U302 ( n = 33), DT204b ( n = 12), and DT49 ( n = 8), were fingerprinted by a combination of well-established genetic methods (pulsed-field gel electrophoresis [PFGE], Pst I/ Sph I [PS] ribotyping, and plasmid profiling). The different techniques identified different degrees of polymorphism (from greatest to least, plasmid profiling [40 types], PS ribotyping [34 types], and PFGE [23 types]). It seems clear that a prevalent genomic clone, as well as a variety of less frequent clones, is present for each of the phage types. In most cases, the prevalent clones appeared within isolates from several animal species and from several geographical locations. We did not find clear evidence of a higher degree of diversity for any of the animal species included, or of any link between isolates from particular animal species and humans. The data presented show the inaccuracy of drawing epidemiological conclusions based on a single fingerprinting method. Strains that share one of the markers do not necessarily belong to the same clone, and a multiple typing approach is required to enable enough discrimination to track strains for epidemiological investigations.

1999-05-01·Applied and Environmental Microbiology2区 · 生物学

Combinations of Intervention Treatments Resulting in 5-Log ₁₀ -Unit Reductions in Numbers of Escherichia coli O157:H7 and Salmonella typhimurium DT104 Organisms in Apple Cider

2区 · 生物学

Article

作者: Uljas, Heidi E. ; Ingham, Steven C.

ABSTRACT The U.S. Food and Drug Administration (FDA) recently mandated a warning statement on packaged fruit juices not treated to reduce target pathogen populations by 5 log 10 units. This study describes combinations of intervention treatments that reduced concentrations of mixtures of Escherichia coli O157:H7 (strains ATCC 43895, C7927, and USDA-FSIS-380-94) or Salmonella typhimurium DT104 (DT104b, U302, and DT104) by 5 log 10 units in apple cider with a pH of 3.3, 3.7, and 4.1. Treatments used were short-term storage at 4, 25, or 35°C and/or freeze-thawing (48 h at −20°C; 4 h at 4°C) of cider with or without added organic acids (0.1% lactic acid, sorbic acid [SA], or propionic acid). Treatments more severe than those for S. typhimurium DT104 were always required to destroy E. coli O157:H7. In pH 3.3 apple cider, a 5-log 10 -unit reduction in E. coli O157:H7 cell numbers was achieved by freeze-thawing or 6-h 35°C treatments. In pH 3.7 cider the 5-log 10 -unit reduction followed freeze-thawing combined with either 6 h at 4°C, 2 h at 25°C, or 1 h at 35°C or 6 h at 35°C alone. A 5-log 10 -unit reduction occurred in pH 4.1 cider after the following treatments: 6 h at 35°C plus freeze-thawing, SA plus 12 h at 25°C plus freeze-thawing, SA plus 6 h at 35°C, and SA plus 4 h at 35°C plus freeze-thawing. Yeast and mold counts did not increase significantly ( P < 0.05) during the 6-h storage at 35°C. Cider with no added organic acids treated with either 6 h at 35°C, freeze-thawing or their combination was always preferred by consumers over pasteurized cider ( P < 0.05). The simple, inexpensive intervention treatments described in the present work could produce safe apple cider without pasteurization and would not require the FDA-mandated warning statement.

100 项与 U-302 相关的药物交易

登录后查看更多信息