Browsing by Subject "Lactic acid"
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Item Development of a carcass sanitizing spray system for small and very small slaughterhouses(Texas A&M University, 2007-04-25) Rodriguez, Jose GabrielSmall and very small slaughterhouses generally spray lactic acid for carcass decontamination utilizing a hand held sprayer. Even though this tool represents a very small investment, it may present important disadvantages such as uneven delivery of the spray over the carcass surface. If the decontamination treatment is not applied properly, the untreated areas of the carcass will still have high bacterial loads present and could be a source for recontamination of the areas that have been treated. A sanitizer spraying system (sanitizing halo system) was designed and assembled. The sanitizing halo system was tested at the Rosenthal Meat Science and Technology Center, Texas A&M University. Thirteen carcasses were split in halves. Thirteen halves were sampled and used as control after knife trimming and water wash; then they were sprayed with 2% L-Lactic at 55????C with the sanitizing halo system. The other 13 halves were sprayed by the RMSTC employees utilizing a hand held sprayer. Counts of aerobic and mesophilic bacteria obtained from carcasses sprayed with the sanitizing halo system and the hand held sprayer were both significantly lower than the control counts. In addition, coliforms counts were below the detectable limit for the sanitizing halo system and the hand held sprayer. After testing, the sanitizing halo system was installed at two small commercial slaughter plants processing beef and pork carcasses. At each slaughter plant, 24 carcass halves were treated with 2% L-Lactic at 55????C using the sanitizing halo system, and the other 24 halves were used as control. Mesophilic bacteria populations were reduced in beef and pork carcasses by 2.9 and 1.9 log cycles, respectively, after the lactic acid treatment. Also E. coli counts were significantly lower in the three regions sampled after application of the 2% L-Lactic acid with the sanitizing halo system. From the data collected during this study, we recommend the sanitizing halo system as a tool to reduce the bacterial loads on the surface of beef and pork carcasses. The use of this system should help small and very small slaughterhouses to improve food safety performance while providing cost-efficiency, simplicity, and convenience.Item The repercussions of exposure to nalidixic acid for Salmonella Typhimurium: Alterations in phenotype, multi-drug resistance and lactic acid susceptibility(Texas Tech University, 2005-12) Mann, Karen M. K.; Brashears, Mindy M.; Blanton, John R.; Reilly, Brian D.; Francisco, Michael J. D. S.; Thompson, Leslie D.; Warner, Ronald D.Antimicrobial drug resistance in foodborne pathogens has increased in importance for human and animal medicine as well as the food industry. Fluoroquinolones, like ciprofloxacin, are used to treat foodborne infections such as salmonellosis, and resistance to the first-generation quinolone, nalidixic acid, can predict decreased susceptibility to ciprofloxacin. Nalidixic acid is used in food microbiology research to create marker strains similar to the wild-type strain that can be isolated from background flora in foods. Nalidixic acid resistant mutants of Salmonella Typhimurium were developed from a single wild-type strain and examined for alterations in phenotype, multi-drug resistance and lactic acid susceptibility; 18 mutants were developed for full resistance (¡Ý 32 ¦Ìg/ml nalidixic acid) and 12 mutants for intermediate resistance (16 ¦Ìg/ml or 25 ¦Ìg/ml nalidixic acid). The wild-type and mutant strains were confirmed as Salmonella using standard techniques, validated for resistance level to nalidixic acid and examined for cross-resistance to other antimicrobial drugs. The wild-type strain, a cocktail of multi-drug resistant Salmonella Typhimurium DT104 and six nalidixic acid resistant mutants were examined for susceptibility to 1% lactic acid and growth in tryptic soy broth (TSB). Compared to the wild-type strain, two mutants had altered serotypes, and 12 mutants displayed cross-resistance to other antimicrobial drugs. One strain was resistant to six antimicrobial drugs: nalidixic acid, cefoxitin, chloramphenicol, sulfisoxazole, streptomycin and tetracycline. This resistance pattern was similar to the multi-drug resistance pattern associated with Salmonella Typhimurium DT104. For two mutants, area under the growth curve in TSB was significantly (P<0.01) different from the wild-type strain. In lactic acid, one mutant (resistant to five antimicrobial drugs) had a lower (P<0.05) area under the growth curve compared to the wild-type strain and the other mutants. The DT104 cocktail had a lower (P=0.0696) area under the growth curve than the wild-type strain. Resistance to several antimicrobial drugs appeared to increase susceptibility to lactic acid. The development of resistance to nalidixic acid can result in significant alterations in phenotype, antimicrobial drug resistance and growth characteristics emphasizing the importance of strain validation prior to experimental use and the importance of limiting nalidixic acid resistance in environmental isolates.Item The repercussions of exposure to nalidixic acid for Salmonella Typhimurium: alterations in phenotype, multi-drug resistance and lactic acid susceptibility(Texas Tech University, 2005-12) Mann, Karen M. K.; Brashears, Mindy M.; Blanton, John R.; Reilly, Brian D.; Francisco, Michael J. D. S.; Thompson, Leslie D.; Warner, Ronald D.Antimicrobial drug resistance in foodborne pathogens has increased in importance for human and animal medicine as well as the food industry. Fluoroquinolones, like ciprofloxacin, are used to treat foodborne infections such as salmonellosis, and resistance to the first-generation quinolone, nalidixic acid, can predict decreased susceptibility to ciprofloxacin. Nalidixic acid is used in food microbiology research to create marker strains similar to the wild-type strain that can be isolated from background flora in foods. Nalidixic acid resistant mutants of Salmonella Typhimurium were developed from a single wild-type strain and examined for alterations in phenotype, multi-drug resistance and lactic acid susceptibility; 18 mutants were developed for full resistance (¡Ý 32 ¦Ìg/ml nalidixic acid) and 12 mutants for intermediate resistance (16 ¦Ìg/ml or 25 ¦Ìg/ml nalidixic acid). The wild-type and mutant strains were confirmed as Salmonella using standard techniques, validated for resistance level to nalidixic acid and examined for cross-resistance to other antimicrobial drugs. The wild-type strain, a cocktail of multi-drug resistant Salmonella Typhimurium DT104 and six nalidixic acid resistant mutants were examined for susceptibility to 1% lactic acid and growth in tryptic soy broth (TSB). Compared to the wild-type strain, two mutants had altered serotypes, and 12 mutants displayed cross-resistance to other antimicrobial drugs. One strain was resistant to six antimicrobial drugs: nalidixic acid, cefoxitin, chloramphenicol, sulfisoxazole, streptomycin and tetracycline. This resistance pattern was similar to the multi-drug resistance pattern associated with Salmonella Typhimurium DT104. For two mutants, area under the growth curve in TSB was significantly (P<0.01) different from the wild-type strain. In lactic acid, one mutant (resistant to five antimicrobial drugs) had a lower (P<0.05) area under the growth curve compared to the wild-type strain and the other mutants. The DT104 cocktail had a lower (P=0.0696) area under the growth curve than the wild-type strain. Resistance to several antimicrobial drugs appeared to increase susceptibility to lactic acid. The development of resistance to nalidixic acid can result in significant alterations in phenotype, antimicrobial drug resistance and growth characteristics emphasizing the importance of strain validation prior to experimental use and the importance of limiting nalidixic acid resistance in environmental isolates.