Stationary-phase cells of Listeria monocytogenes grown in glucose-free or glucose-containing medi... more Stationary-phase cells of Listeria monocytogenes grown in glucose-free or glucose-containing media were exposed for 90 min to various stresses, including acid stress (pH 4.0 to 7.0), osmotic stress (10.5 to 20.5 % NaCl), and various temperatures (5 to 50°C), and were further exposed to pH 3.5. Exposure to a mildly acidic (pH 5.0 to 6.0) environment provided protection of the pathogen against acid upon subsequent exposure. This adaptive response, however, was found to be strongly dependent on other environmental conditions during the shock, such as temperature or the simultaneous presence of a second stress factor (NaCl). Growth of L. monocytogenes in the presence of glucose resulted in enhanced survival of the pathogen at pH 3.5. Sublethal stresses other than acidic stresses, i.e., osmotic, heat, and low-temperature stresses, did not affect the acid resistance of L. monocytogenes (P> 0.5). More-severe levels of these stresses, however, resulted in sensitization of the pathogen to...
Ruminants are one of the reservoirs for Listeria, Salmonella and Escherichia coli O157:H7, and th... more Ruminants are one of the reservoirs for Listeria, Salmonella and Escherichia coli O157:H7, and therefore a potential source of contamination for the household environment. Understanding consumer behavior may help in reducing infections caused by these microorganisms. This study evaluated consumer behaviors in households with/without ruminants, which may be related to increased prevalence of these pathogens. The study was completed over a three-year period, with samples collected during years 1 and 3. Rural Colorado households were recruited, and samples (food, environmental, and fecal) were collected and tested for Listeria, Salmonella and E. coli O157:H7 presence. Participants answered surveys regarding household cleaning habits and food/animal handling. None of the samples tested positive for E. coli O157:H7, while Salmonella was isolated only from households with ruminants. Listeria spp. was isolated from all types of samples with higher, but not significant (P ≥ 0.05), prevalenc...
One steam-vacuuming unit (Unit A) was evaluated for removal of visible contamination and reductio... more One steam-vacuuming unit (Unit A) was evaluated for removal of visible contamination and reduction of bacterial counts on beef carcass surfaces in five processing plants; a second steam-vacuuming unit (Unit B) was evaluated in two of those same plants at a later date. Experimental treatments included appropriate Controls: steam vacuuming carcass surfaces with or without visible contamination, and knife trimming surfaces with visible contamination. Depending on the processing plant, carcasses were tested on the midline or on the round. Each treatment was applied to a 103-cm2 area of the carcass surface, which was scored for visible contamination and analyzed for aerobic plate counts (APC) at 25°C and for total coliform counts (TCC). Average reductions in APC of 0.57 (Unit A) and 0.72 (Unit B) log CFU/cm2 and in TCC of 0.33 (Unit A) and 0.26 (Unit B) log CFU/cm2 were obtained by steam-vacuuming carcass surfaces which had no visible fecal contamination. Steam vacuuming and knife trimmi...
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Three strains of Escherichia coli O157:H7 were grown in tryptic soy broth (TSB) or in a sterile c... more Three strains of Escherichia coli O157:H7 were grown in tryptic soy broth (TSB) or in a sterile cattle manure extract at 35°C for 18 ± 2 h. Aliquots from both inocula containing 106 CFU/ml were used to inoculate 1-cm3 cubes of beef muscle or adipose tissue by immersion for 20 min at 21°C. After removal from the inoculum, one-half of the samples were analyzed for bacterial cell numbers and pH, and the other half were stored at 4°C for 2 or 3 h before analysis. Samples were analyzed by enumerating bacteria present in liquid droplets deposited on the tissue and bacteria loosely or strongly attached to the tissue in order to determine attachment strength. Total numbers of cells on beef muscle tissue (bacteria in liquid droplets, as well as those loosely and strongly attached) were 5.65 ± 0.14 and 5.76 ± 0.26 log CFU/cm2 for E. coli O157:H7 inocula grown in TSB and manure extract, respectively. The differences in attachment strength between inocula from the two media were not significant...
Ten grain-fed steers or heifers were selected to be dehaired at slaughter, while another 10 cattl... more Ten grain-fed steers or heifers were selected to be dehaired at slaughter, while another 10 cattle (of the same kind) were slaughtered and dressed without dehairing. The carcasses of these animals were evaluated for bacterial contamination (aerobic plate count [APC], total coliform count [TCC], Escherichia coli biotype I, and count and presence of Salmonella spp. and Listeria monocytogenes) after sampling from the brisket, flank, and inside round at each of three sites (after dehiding, after evisceration, and after final carcass washing). Visual defects (hairs and specks) and weight associated with trimmings were also evaluated. Overall, there were no major differences in APC, TCC, or E. coli counts between samples from dehaired cattle and those from conventionally slaughtered animals. Dehaired carcasses had fewer (P < 0.05) visible specks and fewer total carcass defects before trimming (but not after trimming) than did carcasses of conventionally slaughtered animals. There were ...
Separate inocula of four strains of Listeria monocytogenes were prepared at 4°C and inoculated (3... more Separate inocula of four strains of Listeria monocytogenes were prepared at 4°C and inoculated (3.58 to 4.67 log10 colony forming units [CFU]/g) in top round ground beef (< 4.0% fat) patties (78.8 ± 6.7 g) of normal (5.47 ± 0.03) or high (6.14 ± 0.08) pH, which were stored (4°C) vacuum-packaged for 56 days and analyzed for L. monocytogenes, total aerobic plate counts (APC) and pH. In normal-pH ground beef, strain N-7143 (serotype 3a), multiplied from 4.25 ± 0.71 log10 CFU/g at day of inoculation to 6.53 ± 0.34 log10 CFU/g at 35 days of storage (P < 0.05); a 2.3 log10 CFU/g increase. Populations of strain Na-19 (serotype 3b) increased 1.8 log10 CFU/g in 35 days of storage, while numbers of strain Na-16 (serotype 1/2a) did not change (P > 0.05) during the 56 days of storage. Strain Scott A (serotype 4b) decreased in numbers from 4.00 ± 1.21 log10 CFU/g at day-0 to 2.72 ± 0.98 log10 CFU/g at 56 days. Populations of strain Scott A were lower (P < 0.05) than other strains aft...
Spore suspensions of Bacillus stearothermophilus (ATCC 7953, 10149, 12980), Bacillus subtilis (AT... more Spore suspensions of Bacillus stearothermophilus (ATCC 7953, 10149, 12980), Bacillus subtilis (ATCC 6633), Bacillus subtilis var. niger (ATCC 9372), Bacillus pumilus (ATCC 27142, and a wild strain) and Bacillus cereus (ATCC 11778) were heated (20 min at 121°C for thermophiles, and 2.5–20 min at 100°C, 105°C, or 107°C for mesophiles) in 1 ml sealed ampoules. Surviving spores were recovered by a 5-tube most probable number (MPN) procedure with soybean casein digest (SCD) or fluid thioglycollate (FTH) broths containing variable concentrations of solids. Numbers of heated thermophilic spores (ATCC 7953) recovered with SCD broths were approximately 1.5 log MPN/ml higher at the 100% broth solids concentration than numbers recovered with FTH broth. Increasing the solids of SCD broth to twice the recommended amount (200%) reduced recovery of heated thermophilic spores compared to regular (100%) strength broth. Recovery of heated thermophilic spores with SCD or FTH broths was higher (P < ...
A direct elevated temperature plate count method utilizing modified fecal coliform agar with roso... more A direct elevated temperature plate count method utilizing modified fecal coliform agar with rosolic acid (ETPC/mFC) was compared to 5-tube and 3-tube most probable number (MPN) procedures for its accuracy in enumerating fecal coliforms and Escherichia coli in naturally and artificially contaminated soft-shell clams (Mya arenaria). The results indicated that the extent of overall recovery of fecal coliforms was similar in the two methods tested. Therefore, the ETPC/mFC method may be considered as a rapid procedure for fecal coliform screening during depuration of soft-shell clams.
This study compares recoveries of Vibrio parahaemolyticus and Vibrio vulnificus with salt-polymyx... more This study compares recoveries of Vibrio parahaemolyticus and Vibrio vulnificus with salt-polymyxin B broth (SPB) and alkaline peptone water (APW) from samples of crab legs, oysters, shrimp, lobster and shark, which were inoculated at three levels (approximately 101 to 102, 102 to 103 and 104 to 105/g) with each of the pathogens. Six samples of each product were analyzed [3-tube most probable number (MPN)] with each broth. Inoculated samples of oysters and slurries of crab and lobster were also tested after cold stress (refrigerated at 2 to 4°C, 3 or 7 days, or frozen at −15°C for 21 or 28 days). For each seafood, geometric means of cells recovered with APW were significantly (P < 0.05) higher than the corresponding means of recovery with SPB. In addition, 12 of 15 calculated estimates of 50% relative detectable levels (RDL50) were lower (P < 0.05) for APW than for SPB. In these samples, the level of detection by APW was found to be 40 to 32,000 and 6- to 42-fold lower for V p...
Carbapenems are broad-spectrum β-lactam antimicrobials used for the treatment of serious infectio... more Carbapenems are broad-spectrum β-lactam antimicrobials used for the treatment of serious infections in humans. To date only sporadic studies have reported the occurrence of carbapenemase-producing (CP) bacteria in foodproducing animals and their environment. The bacteria and enzymes isolated include VIM-1 producing Escherichia coli and Salmonella Infantis from pigs and poultry in Germany, OXA-23-producing Acinetobacter spp. from cattle and horses in France and Belgium, and NDM-producing Acinetobacter spp. from pigs and poultry in China. In the German S. Infantis and E. coli isolates, the VIM-1-encoding genes were located on IncHI2 plasmids. A methodology including selective culture is proposed for the detection of CP strains of Enterobacteriaceae and Acinetobacter spp. The choice of selective media for the surveillance of carbapenem resistance for testing animal and food samples needs to be experimentally evaluated and validated. Biochemical and phenotypic tests for the confirmatory identification of CP bacteria are available. For CP bacteria in animals and food, active/passive monitoring and/or targeted surveys should cover key zoonotic agents, animal pathogens and indicator organisms. Priority should be given to broilers, fattening turkeys, fattening pigs, veal calves and meat thereof. Because there are no data on the comparative efficacy of individual control options, prioritisation is complex. Continued prohibition of the use of carbapenems in food-producing animals would be a simple and effective option. As genes encoding carbapenemase production are mostly plasmid-mediated, and co-resistance may be an important issue in the spread of such resistance mechanisms, decreasing the frequency of use of antimicrobials in animal production in the EU in accordance with prudent use guidelines is also of high priority. The effectiveness of any control measures should be monitored by targeted surveys, using selective isolation methods and pre-enrichment of samples. Control measures should be proactively implemented at national and international levels to prevent CP strains become widespread in livestock.
Culture suspensions of 45 species and strains of Listeria were prepared in tryptic soy broth with... more Culture suspensions of 45 species and strains of Listeria were prepared in tryptic soy broth with 0.6% yeast extract (TSBYE) for 24 h at 37°C, and were then diluted with phosphate buffer solution and standardized to 0.10 ± 0.01 absorbance at 600 nm. Spectrophotometer tubes containing 5 ml of TSBYE (pH 7.2) were inoculated with 0.1 ml of the standardized cultures and incubated at 4, 10 or 37°C. Absorbance readings were taken during storage. Growth curves were fitted using the Gompertz function, and growth parameters were calculated. There were major differences in lag phase duration (LPD), generation time (GT) and exponential growth rate (EGR) among species and strains of Listeria tested. Values for LPD and GT decreased (P <0.05) with increasing temperature of incubation, while EGR and maximum population density (MPD) values increased. Lag phase duration and GT values at a given temperature were lower for Listeria monocytogenes compared to other Listeria spp. At 4°C, LPDs for L. m...
Various chemical solutions (5% hydrogen peroxide, 0.5% ozone, 12% trisodium phosphate, 2% acetic ... more Various chemical solutions (5% hydrogen peroxide, 0.5% ozone, 12% trisodium phosphate, 2% acetic acid, and 0.3% commercial sanitizer), water (16 to 74°C) spray-washing interventions, and hand-trimming/spray-washing treatments were compared for their ability to remove fecal material and to reduce bacterial contamination on beef brisket fat samples in a model spray-washing cabinet. The samples were inoculated with 2.5 cm2 of a bovine fecal paste inoculated with Escherichia coli (ATCC 11370). Hand-trimming followed by spray-washing with plain water (16 to 74°C when it came in contact with the sample; 20.68 bar pressure; for 36 or 12 s corresponding to chain speeds of 100 or 300 carcasses per h) lowered (P < 0.05) microbiological counts, compared to the inoculated control, by 1.41 to 2.50 log colony-forming units (CFU)/cm2. Additionally, spraying with chemical solutions (16°C; 1.38 bar, 12 or 36 s), before or after spray-washing with plain water (20.68 bar) of 16°C (36 s), 35°C (12 s...
This study examined the effect of exposure time of beef-fat fascia to an inoculated fecal paste o... more This study examined the effect of exposure time of beef-fat fascia to an inoculated fecal paste on the efficiency of removal of bacteria by spray washing or rinsing. Brisket fat (obtained <15 min postmortem) samples (10 by 10 by 2 cm) were inoculated, in the geometric center of their fascia surface, with four 0.64-cm diameter loops of a bovine fecal paste containing an inoculum (108 CFU/g) of streptomycin-resistant Escherichia coli ATTC 11370. Triplicate samples were spray washed with water (35°C, 20.7 bar) and then rinsed with solutions of 2% acetic acid, 5% hydrogen peroxide, or 12% trisodium phosphate, or spray washed with water at 35°C or 74°C (20.7 bar), in an automated spray-washing cabinet for 12 s, after 0, 2, or 4 h of exposure to the inoculated fecal paste. The samples were analyzed for streptomycin-resistant bacterial counts. Washing or washing/rinsing at time 0 (immediately after exposure to the inoculated fecal paste) with trisodium phosphate, 35°C water, hydrogen pe...
Microbiological and visual evaluations were performed to compare the efficacy of hand trimming, s... more Microbiological and visual evaluations were performed to compare the efficacy of hand trimming, spray washing, or a combination of treatments, in the removal of bacteria and fecal material from beef adipose tissue. Subcutaneous adipose samples with intact fascia from the surfaces of briskets (obtained within 15 min postmortem) were inoculated on different sizes of surface areas (0, 0.3125, 0,625, 1.25, 1.875, or 2.50 cm2) with a bovine fecal paste containing a culture of streptomycin-resistant Escherichia coli ATCC 11370. The samples were then spray washed with water at 35°C in a specially designed automated spray washing cabinet at pressures of 2.76, 13.79, 20.68, or 27.58 bar and at chain speeds equivalent to 100, 200, or 300 carcasses per hour (exposure times of 36, 18, or 12 s). Total aerobic mesophilic plate counts, streptomycin-resistant bacterial plate counts and visual scores for fecal contamination were obtained. There was a reduction (P < 0.05) in microbiological counts...
Objective This study compared knowledge and food-handling behavior after pathogen-specific (exper... more Objective This study compared knowledge and food-handling behavior after pathogen-specific (experimental treatment) versus basic food safety instruction (active control) presented during nutrition education classes for low-income English- and Spanish-language pregnant women. Methods Subjects (n = 550) were randomly assigned to treatment groups in two different locations in the United States. Food safety instruction was part of an 8-lesson curriculum. Food safety knowledge and behavior were measured pre/post intervention. Descriptive data were analyzed by Chi-Square or ANOVA; changes after intervention were analyzed by regression analysis. Results Knowledge improved after intervention in the pathogen-specific treatment group compared to active control, especially among Spanish-language women. Behavior change after intervention for the pathogen-specific treatment group improved for thermometer usage, refrigeration and consumption of foods at high risk for safety; however, all other im...
Stationary-phase cells of Listeria monocytogenes grown in glucose-free or glucose-containing medi... more Stationary-phase cells of Listeria monocytogenes grown in glucose-free or glucose-containing media were exposed for 90 min to various stresses, including acid stress (pH 4.0 to 7.0), osmotic stress (10.5 to 20.5 % NaCl), and various temperatures (5 to 50°C), and were further exposed to pH 3.5. Exposure to a mildly acidic (pH 5.0 to 6.0) environment provided protection of the pathogen against acid upon subsequent exposure. This adaptive response, however, was found to be strongly dependent on other environmental conditions during the shock, such as temperature or the simultaneous presence of a second stress factor (NaCl). Growth of L. monocytogenes in the presence of glucose resulted in enhanced survival of the pathogen at pH 3.5. Sublethal stresses other than acidic stresses, i.e., osmotic, heat, and low-temperature stresses, did not affect the acid resistance of L. monocytogenes (P> 0.5). More-severe levels of these stresses, however, resulted in sensitization of the pathogen to...
Ruminants are one of the reservoirs for Listeria, Salmonella and Escherichia coli O157:H7, and th... more Ruminants are one of the reservoirs for Listeria, Salmonella and Escherichia coli O157:H7, and therefore a potential source of contamination for the household environment. Understanding consumer behavior may help in reducing infections caused by these microorganisms. This study evaluated consumer behaviors in households with/without ruminants, which may be related to increased prevalence of these pathogens. The study was completed over a three-year period, with samples collected during years 1 and 3. Rural Colorado households were recruited, and samples (food, environmental, and fecal) were collected and tested for Listeria, Salmonella and E. coli O157:H7 presence. Participants answered surveys regarding household cleaning habits and food/animal handling. None of the samples tested positive for E. coli O157:H7, while Salmonella was isolated only from households with ruminants. Listeria spp. was isolated from all types of samples with higher, but not significant (P ≥ 0.05), prevalenc...
One steam-vacuuming unit (Unit A) was evaluated for removal of visible contamination and reductio... more One steam-vacuuming unit (Unit A) was evaluated for removal of visible contamination and reduction of bacterial counts on beef carcass surfaces in five processing plants; a second steam-vacuuming unit (Unit B) was evaluated in two of those same plants at a later date. Experimental treatments included appropriate Controls: steam vacuuming carcass surfaces with or without visible contamination, and knife trimming surfaces with visible contamination. Depending on the processing plant, carcasses were tested on the midline or on the round. Each treatment was applied to a 103-cm2 area of the carcass surface, which was scored for visible contamination and analyzed for aerobic plate counts (APC) at 25°C and for total coliform counts (TCC). Average reductions in APC of 0.57 (Unit A) and 0.72 (Unit B) log CFU/cm2 and in TCC of 0.33 (Unit A) and 0.26 (Unit B) log CFU/cm2 were obtained by steam-vacuuming carcass surfaces which had no visible fecal contamination. Steam vacuuming and knife trimmi...
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Three strains of Escherichia coli O157:H7 were grown in tryptic soy broth (TSB) or in a sterile c... more Three strains of Escherichia coli O157:H7 were grown in tryptic soy broth (TSB) or in a sterile cattle manure extract at 35°C for 18 ± 2 h. Aliquots from both inocula containing 106 CFU/ml were used to inoculate 1-cm3 cubes of beef muscle or adipose tissue by immersion for 20 min at 21°C. After removal from the inoculum, one-half of the samples were analyzed for bacterial cell numbers and pH, and the other half were stored at 4°C for 2 or 3 h before analysis. Samples were analyzed by enumerating bacteria present in liquid droplets deposited on the tissue and bacteria loosely or strongly attached to the tissue in order to determine attachment strength. Total numbers of cells on beef muscle tissue (bacteria in liquid droplets, as well as those loosely and strongly attached) were 5.65 ± 0.14 and 5.76 ± 0.26 log CFU/cm2 for E. coli O157:H7 inocula grown in TSB and manure extract, respectively. The differences in attachment strength between inocula from the two media were not significant...
Ten grain-fed steers or heifers were selected to be dehaired at slaughter, while another 10 cattl... more Ten grain-fed steers or heifers were selected to be dehaired at slaughter, while another 10 cattle (of the same kind) were slaughtered and dressed without dehairing. The carcasses of these animals were evaluated for bacterial contamination (aerobic plate count [APC], total coliform count [TCC], Escherichia coli biotype I, and count and presence of Salmonella spp. and Listeria monocytogenes) after sampling from the brisket, flank, and inside round at each of three sites (after dehiding, after evisceration, and after final carcass washing). Visual defects (hairs and specks) and weight associated with trimmings were also evaluated. Overall, there were no major differences in APC, TCC, or E. coli counts between samples from dehaired cattle and those from conventionally slaughtered animals. Dehaired carcasses had fewer (P < 0.05) visible specks and fewer total carcass defects before trimming (but not after trimming) than did carcasses of conventionally slaughtered animals. There were ...
Separate inocula of four strains of Listeria monocytogenes were prepared at 4°C and inoculated (3... more Separate inocula of four strains of Listeria monocytogenes were prepared at 4°C and inoculated (3.58 to 4.67 log10 colony forming units [CFU]/g) in top round ground beef (< 4.0% fat) patties (78.8 ± 6.7 g) of normal (5.47 ± 0.03) or high (6.14 ± 0.08) pH, which were stored (4°C) vacuum-packaged for 56 days and analyzed for L. monocytogenes, total aerobic plate counts (APC) and pH. In normal-pH ground beef, strain N-7143 (serotype 3a), multiplied from 4.25 ± 0.71 log10 CFU/g at day of inoculation to 6.53 ± 0.34 log10 CFU/g at 35 days of storage (P < 0.05); a 2.3 log10 CFU/g increase. Populations of strain Na-19 (serotype 3b) increased 1.8 log10 CFU/g in 35 days of storage, while numbers of strain Na-16 (serotype 1/2a) did not change (P > 0.05) during the 56 days of storage. Strain Scott A (serotype 4b) decreased in numbers from 4.00 ± 1.21 log10 CFU/g at day-0 to 2.72 ± 0.98 log10 CFU/g at 56 days. Populations of strain Scott A were lower (P < 0.05) than other strains aft...
Spore suspensions of Bacillus stearothermophilus (ATCC 7953, 10149, 12980), Bacillus subtilis (AT... more Spore suspensions of Bacillus stearothermophilus (ATCC 7953, 10149, 12980), Bacillus subtilis (ATCC 6633), Bacillus subtilis var. niger (ATCC 9372), Bacillus pumilus (ATCC 27142, and a wild strain) and Bacillus cereus (ATCC 11778) were heated (20 min at 121°C for thermophiles, and 2.5–20 min at 100°C, 105°C, or 107°C for mesophiles) in 1 ml sealed ampoules. Surviving spores were recovered by a 5-tube most probable number (MPN) procedure with soybean casein digest (SCD) or fluid thioglycollate (FTH) broths containing variable concentrations of solids. Numbers of heated thermophilic spores (ATCC 7953) recovered with SCD broths were approximately 1.5 log MPN/ml higher at the 100% broth solids concentration than numbers recovered with FTH broth. Increasing the solids of SCD broth to twice the recommended amount (200%) reduced recovery of heated thermophilic spores compared to regular (100%) strength broth. Recovery of heated thermophilic spores with SCD or FTH broths was higher (P < ...
A direct elevated temperature plate count method utilizing modified fecal coliform agar with roso... more A direct elevated temperature plate count method utilizing modified fecal coliform agar with rosolic acid (ETPC/mFC) was compared to 5-tube and 3-tube most probable number (MPN) procedures for its accuracy in enumerating fecal coliforms and Escherichia coli in naturally and artificially contaminated soft-shell clams (Mya arenaria). The results indicated that the extent of overall recovery of fecal coliforms was similar in the two methods tested. Therefore, the ETPC/mFC method may be considered as a rapid procedure for fecal coliform screening during depuration of soft-shell clams.
This study compares recoveries of Vibrio parahaemolyticus and Vibrio vulnificus with salt-polymyx... more This study compares recoveries of Vibrio parahaemolyticus and Vibrio vulnificus with salt-polymyxin B broth (SPB) and alkaline peptone water (APW) from samples of crab legs, oysters, shrimp, lobster and shark, which were inoculated at three levels (approximately 101 to 102, 102 to 103 and 104 to 105/g) with each of the pathogens. Six samples of each product were analyzed [3-tube most probable number (MPN)] with each broth. Inoculated samples of oysters and slurries of crab and lobster were also tested after cold stress (refrigerated at 2 to 4°C, 3 or 7 days, or frozen at −15°C for 21 or 28 days). For each seafood, geometric means of cells recovered with APW were significantly (P < 0.05) higher than the corresponding means of recovery with SPB. In addition, 12 of 15 calculated estimates of 50% relative detectable levels (RDL50) were lower (P < 0.05) for APW than for SPB. In these samples, the level of detection by APW was found to be 40 to 32,000 and 6- to 42-fold lower for V p...
Carbapenems are broad-spectrum β-lactam antimicrobials used for the treatment of serious infectio... more Carbapenems are broad-spectrum β-lactam antimicrobials used for the treatment of serious infections in humans. To date only sporadic studies have reported the occurrence of carbapenemase-producing (CP) bacteria in foodproducing animals and their environment. The bacteria and enzymes isolated include VIM-1 producing Escherichia coli and Salmonella Infantis from pigs and poultry in Germany, OXA-23-producing Acinetobacter spp. from cattle and horses in France and Belgium, and NDM-producing Acinetobacter spp. from pigs and poultry in China. In the German S. Infantis and E. coli isolates, the VIM-1-encoding genes were located on IncHI2 plasmids. A methodology including selective culture is proposed for the detection of CP strains of Enterobacteriaceae and Acinetobacter spp. The choice of selective media for the surveillance of carbapenem resistance for testing animal and food samples needs to be experimentally evaluated and validated. Biochemical and phenotypic tests for the confirmatory identification of CP bacteria are available. For CP bacteria in animals and food, active/passive monitoring and/or targeted surveys should cover key zoonotic agents, animal pathogens and indicator organisms. Priority should be given to broilers, fattening turkeys, fattening pigs, veal calves and meat thereof. Because there are no data on the comparative efficacy of individual control options, prioritisation is complex. Continued prohibition of the use of carbapenems in food-producing animals would be a simple and effective option. As genes encoding carbapenemase production are mostly plasmid-mediated, and co-resistance may be an important issue in the spread of such resistance mechanisms, decreasing the frequency of use of antimicrobials in animal production in the EU in accordance with prudent use guidelines is also of high priority. The effectiveness of any control measures should be monitored by targeted surveys, using selective isolation methods and pre-enrichment of samples. Control measures should be proactively implemented at national and international levels to prevent CP strains become widespread in livestock.
Culture suspensions of 45 species and strains of Listeria were prepared in tryptic soy broth with... more Culture suspensions of 45 species and strains of Listeria were prepared in tryptic soy broth with 0.6% yeast extract (TSBYE) for 24 h at 37°C, and were then diluted with phosphate buffer solution and standardized to 0.10 ± 0.01 absorbance at 600 nm. Spectrophotometer tubes containing 5 ml of TSBYE (pH 7.2) were inoculated with 0.1 ml of the standardized cultures and incubated at 4, 10 or 37°C. Absorbance readings were taken during storage. Growth curves were fitted using the Gompertz function, and growth parameters were calculated. There were major differences in lag phase duration (LPD), generation time (GT) and exponential growth rate (EGR) among species and strains of Listeria tested. Values for LPD and GT decreased (P <0.05) with increasing temperature of incubation, while EGR and maximum population density (MPD) values increased. Lag phase duration and GT values at a given temperature were lower for Listeria monocytogenes compared to other Listeria spp. At 4°C, LPDs for L. m...
Various chemical solutions (5% hydrogen peroxide, 0.5% ozone, 12% trisodium phosphate, 2% acetic ... more Various chemical solutions (5% hydrogen peroxide, 0.5% ozone, 12% trisodium phosphate, 2% acetic acid, and 0.3% commercial sanitizer), water (16 to 74°C) spray-washing interventions, and hand-trimming/spray-washing treatments were compared for their ability to remove fecal material and to reduce bacterial contamination on beef brisket fat samples in a model spray-washing cabinet. The samples were inoculated with 2.5 cm2 of a bovine fecal paste inoculated with Escherichia coli (ATCC 11370). Hand-trimming followed by spray-washing with plain water (16 to 74°C when it came in contact with the sample; 20.68 bar pressure; for 36 or 12 s corresponding to chain speeds of 100 or 300 carcasses per h) lowered (P < 0.05) microbiological counts, compared to the inoculated control, by 1.41 to 2.50 log colony-forming units (CFU)/cm2. Additionally, spraying with chemical solutions (16°C; 1.38 bar, 12 or 36 s), before or after spray-washing with plain water (20.68 bar) of 16°C (36 s), 35°C (12 s...
This study examined the effect of exposure time of beef-fat fascia to an inoculated fecal paste o... more This study examined the effect of exposure time of beef-fat fascia to an inoculated fecal paste on the efficiency of removal of bacteria by spray washing or rinsing. Brisket fat (obtained <15 min postmortem) samples (10 by 10 by 2 cm) were inoculated, in the geometric center of their fascia surface, with four 0.64-cm diameter loops of a bovine fecal paste containing an inoculum (108 CFU/g) of streptomycin-resistant Escherichia coli ATTC 11370. Triplicate samples were spray washed with water (35°C, 20.7 bar) and then rinsed with solutions of 2% acetic acid, 5% hydrogen peroxide, or 12% trisodium phosphate, or spray washed with water at 35°C or 74°C (20.7 bar), in an automated spray-washing cabinet for 12 s, after 0, 2, or 4 h of exposure to the inoculated fecal paste. The samples were analyzed for streptomycin-resistant bacterial counts. Washing or washing/rinsing at time 0 (immediately after exposure to the inoculated fecal paste) with trisodium phosphate, 35°C water, hydrogen pe...
Microbiological and visual evaluations were performed to compare the efficacy of hand trimming, s... more Microbiological and visual evaluations were performed to compare the efficacy of hand trimming, spray washing, or a combination of treatments, in the removal of bacteria and fecal material from beef adipose tissue. Subcutaneous adipose samples with intact fascia from the surfaces of briskets (obtained within 15 min postmortem) were inoculated on different sizes of surface areas (0, 0.3125, 0,625, 1.25, 1.875, or 2.50 cm2) with a bovine fecal paste containing a culture of streptomycin-resistant Escherichia coli ATCC 11370. The samples were then spray washed with water at 35°C in a specially designed automated spray washing cabinet at pressures of 2.76, 13.79, 20.68, or 27.58 bar and at chain speeds equivalent to 100, 200, or 300 carcasses per hour (exposure times of 36, 18, or 12 s). Total aerobic mesophilic plate counts, streptomycin-resistant bacterial plate counts and visual scores for fecal contamination were obtained. There was a reduction (P < 0.05) in microbiological counts...
Objective This study compared knowledge and food-handling behavior after pathogen-specific (exper... more Objective This study compared knowledge and food-handling behavior after pathogen-specific (experimental treatment) versus basic food safety instruction (active control) presented during nutrition education classes for low-income English- and Spanish-language pregnant women. Methods Subjects (n = 550) were randomly assigned to treatment groups in two different locations in the United States. Food safety instruction was part of an 8-lesson curriculum. Food safety knowledge and behavior were measured pre/post intervention. Descriptive data were analyzed by Chi-Square or ANOVA; changes after intervention were analyzed by regression analysis. Results Knowledge improved after intervention in the pathogen-specific treatment group compared to active control, especially among Spanish-language women. Behavior change after intervention for the pathogen-specific treatment group improved for thermometer usage, refrigeration and consumption of foods at high risk for safety; however, all other im...
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Papers by John Sofos