Rapid estimation of Salmonella enterica contamination level in ground beef – Application of the time-to-positivity method using a combination of molecular detection and direct plating

Abstract The 3M™ Molecular Detection Assay (MDA) Salmonella utilizes isothermal amplification of nucleic acid sequences with high specificity, efficiency, rapidity and bioluminescence to detect amplification of Salmonella spp. in food, food-related, and environmental samples after enrichment. A method modification and matrix extension study of the previously approved AOAC Official MethodSM 2013.09 was conducted, and approval of the modification was received on March 20, 2014. Using an unpaired study design in a multilaboratory collaborative study, the 3M MDA Salmonella method was compared to the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) Microbiology Laboratory Guidebook (MLG) 4.05 (2011), Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg, and Catfish Products for raw ground beef and the U.S. Food and Drug Administration (FDA)/Bacteriological Analytical Manual (BAM) Chapter 5, Salmonella reference method for wet dog food following the current AOAC guidelines. A total of 20 laboratories participated. For the 3M MDA Salmonella method, raw ground beef was analyzed using 25 g test portions, and wet dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each matrix were analyzed. Each matrix was artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2–2 CFU/test portion), and a high inoculum level (2–5 CFU/test portion). In this study, 1512 unpaired replicate samples were analyzed. Statistical analysis was conducted according to the probability of detection (POD). For the low-level raw ground beef test portions, the following dLPOD (difference between the LPODs of the reference and candidate method) values with 95% confidence intervals were obtained: –0.01 (–0.14, +0.12). For the low-level wet dog food test portions, the following dLPOD with 95% confidence intervals were obtained: –0.04 (–0.16, +0.09). No significant differences were observed in the number of positive samples detected by the 3M MDA Salmonella method versus either the USDA/FSIS-MLG or FDA/BAM methods.

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An Accelerated Method for Isolation of Salmonella enterica Serotype Typhimurium from Artificially Contaminated Foods, Using a Short Preenrichment, Immunomagnetic Separation, and Xylose-Lysine-Desoxycholate Agar (6IX Method)

Journal of Food Protection ◽

10.4315/0362-028x-72.3.583 ◽

2009 ◽

Vol 72 (3) ◽

pp. 583-590 ◽

Cited By ~ 12

Author(s):

APARNA TATAVARTHY ◽

KEALY PEAK ◽

WILLIAM VEGUILLA ◽

TERESA CUTTING ◽

VALERIE J. HARWOOD ◽

...

Keyword(s):

Salmonella Typhimurium ◽

Salmonella Enterica ◽

Ground Beef ◽

Immunomagnetic Separation ◽

Food Samples ◽

Microbial Load ◽

Source Tracking ◽

Epidemiological Analysis ◽

Rapid Isolation ◽

Peptone Water

Rapid isolation of Salmonella from food is essential for faster typing and source tracking in an outbreak. The objective of this study was to investigate a rapid isolation method that would augment the standard U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM) method. Food samples with low microbial load, including egg salad and ice cream, moderately high–microbial-load tomatoes, and high-microbial-load ground beef were intentionally inoculated with 2 to 48 CFU of Salmonella enterica serotype Typhimurium. The samples were preenriched in buffered peptone water for 6 h, and then selectively concentrated by immunomagnetic separation and plated for isolation on xylose-lysine-desoxycholate agar: the 6IX method. Salmonella Typhimurium was presumptively identified from approximately 97% of the low-microbial-load and moderately high–microbial-load samples by the 6IX method 2 days before the BAM standard method for isolation of Salmonella. In 49% of the beef samples, Salmonella Typhimurium was presumptively identified 1 or 2 days earlier by the 6IX method. Given the inocula used, our data clearly indicated that for most of the food samples tested, with the exception of ground beef, Salmonella Typhimurium could be isolated two laboratory days earlier with the 6IX method compared with the BAM method. In conclusion, this 6IX method may expedite Salmonella isolation and, therefore, has the potential to accelerate strain tracking for epidemiological analysis in a foodborne outbreak.

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Incidence and contamination level of Clostridium perfringens in meat and meat products sold in Sakarya province of Turkey

Food and Health ◽

10.3153/fh21018 ◽

2021 ◽

Vol 7 (3) ◽

pp. 172-178

Author(s):

Serap Coşansu ◽

Şeyma Şeniz Ersöz

Keyword(s):

Clostridium Perfringens ◽

Meat Product ◽

Meat Products ◽

Ground Beef ◽

Chicken Meat ◽

Contamination Level ◽

Biochemical Tests ◽

Contamination Levels ◽

Emulsified Meat ◽

Cooked Meat

Totally 101 meat and meat product samples obtained from local markets and restaurants were analyzed for incidence and contamination level of Clostridium perfringens. The typical colonies grown anaerobically on Tryptose Sulfite Cycloserine Agar supplemented with 4-Methyliumbelliferyl (MUP) were confirmed by biochemical tests. Forty-eight of the samples (47.5%) were contaminated with C. perfringens. The highest incidence of the pathogen was determined in uncooked meatball samples (72.2%) followed by ground beef samples (61.3%). The incidence of C. perfringens in chicken meat, cooked meat döner, cooked chicken döner and emulsified meat product samples were 33.3, 33.3, 28.6 and 16.7%, respectively. Thirteen out of 101 samples (12.9%) yielded typical colonies on TSC-MUP Agar, but could not be confirmed as C. perfringens. Average contamination levels in sample groups ranged from 8.3 to 1.5×102 cfu/g, with the highest ground beef and the lowest chicken meat.

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Prevalence of Multidrug-Resistant Foodborne Pathogens and Indicator Bacteria from Edible Offal and Muscle Meats in Nashville, Tennessee

Foods ◽

10.3390/foods9091190 ◽

2020 ◽

Vol 9 (9) ◽

pp. 1190

Author(s):

Siqin Liu ◽

Agnes Kilonzo-Nthenge ◽

Samuel N. Nahashon ◽

Bharat Pokharel ◽

Abdullah Ibn Mafiz ◽

...

Keyword(s):

Foodborne Pathogens ◽

Salmonella Enterica ◽

Ground Beef ◽

Multidrug Resistant ◽

Indicator Bacteria ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

Beef Liver ◽

E Coli ◽

Retail Meats

This study investigated the prevalence of antimicrobial-resistant bacteria in retail edible offal and muscle meats in Nashville, Tennessee. A total of 348 retail meats (160 edible offal and 188 muscle) were analyzed for Salmonella enterica serovar, Campylobacter, Escherichia coli, E. coli O157:H7, and enterococci. Bacteria was identified using biochemical and PCR methods. Salmonella enterica serovar (4.4% and 4.3%), Campylobacter (1.9% and 1.1%), E. coli (79.4% and 89.4%), and enterococci (88.1% and 95.7%) was detected in offal and muscle meats, respectively. Chicken liver (9.7%) was most frequently contaminated with Salmonella enterica serovar, followed by ground chicken (6.9%) and chicken wings (4.2%). No Salmonella enterica serovar was detected in beef liver, beef tripe, and ground beef. The prevalence of Campylobacter was 6.9%, 2.3%, and 1.4% in beef liver, ground beef, and ground chicken, respectively. None of the meats were positive for E. coli O157:H7. Resistance of isolates was significantly (p < 0.05) highest in erythromycin (98.3%; 99.1%), followed by tetracycline (94%; 98.3%), vancomycin (88.8%; 92.2%) as compared to chloramphenicol (43.1%; 53.9%), amoxicillin/clavulanic (43.5%; 45.7%), and ciprofloxacin (45.7%; 55.7%) in offal and muscle meats, respectively. Imipenem showed the lowest resistance (0%; 0.9%). A total of 41 multidrug-resistant patterns were displayed. Edible offal could be a source of antibiotic-resistant bacteria.

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Evaluation of 3M™ Molecular Detection Assay (MDA) Salmonella for the Detection of Salmonella in Selected Foods: Collaborative Study

Journal of AOAC International ◽

10.5740/jaoacint.13-227 ◽

2013 ◽

Vol 96 (6) ◽

pp. 1325-1335 ◽

Cited By ~ 9

Author(s):

Patrick Bird ◽

Kiel Fisher ◽

Megan Boyle ◽

Travis Huffman ◽

M Joseph Benzinger, Jr ◽

...

Keyword(s):

Confidence Intervals ◽

Molecular Detection ◽

Collaborative Study ◽

Ground Beef ◽

Probability Of Detection ◽

Inoculum Level ◽

Test Portion ◽

Low Level ◽

Dog Food ◽

Detection Assay

Abstract The 3M™ Molecular Detection Assay (MDA) Salmonella is used with the 3M™ Molecular Detection System for the detection of Salmonella spp. in food, food-related, and environmental samples after enrichment. The assay utilizes loop-mediated isothermal amplification to rapidly amplify Salmonella target DNA with high specificity and sensitivity, combined with bioluminescence to detect the amplification. The 3M MDA Salmonella method was compared using an unpaired study design in a multilaboratory collaborative study to the U. S. Department of Agriculture/Food Safety and Inspection Service-Microbiology Laboratory Guidebook (USDA/FSIS-MLG 4.05), Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products for raw ground beef and the U.S. Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) Chapter 5 Salmonella reference method for wet dog food following the current AOAC guidelines. A total of 20 laboratories participated. For the 3M MDA Salmonella method, raw ground beef was analyzed using 25 g test portions, and wet dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each matrix were analyzed. Each matrix was artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2–2 CFU/test portion), and a high inoculum level (2–5 CFU/test portion). In this study, 1512 unpaired replicate samples were analyzed. Statistical analysis was conducted according to the probability of detection (POD). For the low-level raw ground beef test portions, the following dLPOD (difference between the POD of the reference and candidate method) values with 95% confidence intervals were obtained: –0.01 (–0.14, +0.12). For the low-level wet dog food test portions, the following dLPOD with 95% confidence intervals were obtained: –0.04 (–0.16, +0.09). No significant differences were observed in the number of positive samples detected by the 3M MDA Salmonella method versus either the USDA/FSIS-MLG or FDA/BAM methods.

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Characterization of Shiga Toxin-ProducingEscherichia coliIsolated from Ground Beef Collected in Different Socioeconomic Strata Markets in Buenos Aires, Argentina

BioMed Research International ◽

10.1155/2014/795104 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 13

Author(s):

Patricia Llorente ◽

Laura Barnech ◽

Kinue Irino ◽

María Valeria Rumi ◽

Adriana Bentancor

Keyword(s):

Shiga Toxin ◽

Buenos Aires ◽

Ground Beef ◽

Contamination Level ◽

Contamination Rate ◽

E Coli ◽

Virulence Markers ◽

Route Of Transmission ◽

Socioeconomic Strata

Consumption of raw/undercooked ground beef is the most common route of transmission of Shiga toxin-producingE. coli(STEC). The aim of the study was to determine the STEC contamination level of the ground beef samples collected in 36 markets of different socioeconomic strata in Buenos Aires, Argentina, and the characterization of the isolated strains. Ninety-one out of 252 (36.1%) samples werestx+. Fifty-seven STEC strains were recovered. Eleven STEC strains belonged to O157 serogroup, and 46 to non-O157 serogroups. Virulence markers of the 57 STEC werestx1, 5.3% (3/57);stx2, 86.0% (49/57);stx1/stx2, 8.8% (5/57);ehxA, 61.4% (35/57);eae, 26.3% (15/57);saa, 24.6% (14/57). Shiga toxin subtypes werestx2, 31.5% (17/54);stx2c-vhb, 24.1% (13/54);stx2c-vha, 20.4% (11/54);stx2/stx2c-vha, 14.8% (8/54);stx2/stx2c-vhb, 5.6% (3/54);stx2c-vha/vhb, 3.7% (2/54). Serotypes O178:H19 and O157:H7 were prevalent. Contamination rate of STEC in all strata was high, and the highest O157 contamination was observed at low strata at several sampling rounds. Persistence of STEC was not detected. Sixteen strains (28.1%) were resistant to ampicillin, streptomycin, amikacin, or tetracycline. The STEC contamination level of ground beef could vary according to the sociocultural characteristics of the population.

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