Occurrence of Nontuberculous Mycobacteria, Salmonella, Listeria monocytogenes and Staphylococcus aureus in Artisanal Unpasteurized Cheeses in the State of Michoacan, Mexico

2020 ◽  
Author(s):  
Ricardo Jiovanni Soria-Herrera ◽  
Karla Gabriela Dominguez-Gonzalez ◽  
Rebeca Rumbo-Pino ◽  
Arizbeth Piña-Lazaro ◽  
Jose Jesus Alvarez-Perez ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Nontuberculous Mycobacteria ◽  
Microbiological Quality ◽  
The State ◽  
Fecal Coliforms ◽  
Health Authorities ◽  
Unpasteurized Milk ◽  
Fresh Cheese ◽  
And Staphylococcus Aureus

This study investigated the presence of nontuberculous mycobacteria (NTM) for the first time in two types of unpasteurized fresh cheese produced in the state of Michoacan, Mexico. We tested for this pathogen along with the others to broaden the study of microbiological quality in a total of 60 samples of cheese, 30 fresh and 30 adobera, which were collected from six artisanal cheese factories (ACF). The hygienic conditions of these establishments and the practices of cheese manufacture were generally poor. Although Mycobacterium bovis was not detected, four cheese samples harbored NTM isolates. The four NTM isolates were identified using three molecular markers (hsp65, rrs and rpoB genes) which corresponded to Mycolicibacterium fortuitum (n=3) and Mycolicibacterium mageritense (n=1). All 60 cheese samples analyzed had unsatisfactory microbiological quality according to the Mexican Official Guideline. Regarding fresh cheeses, all 30 samples analyzed were positive for aerobic mesophilic bacteria (AMB), total coliforms (TC), fecal coliforms (FC) and yeasts and moulds. Escherichia coli and Staphylococcus aureus were present in 23 and 21 samples, respectively. Listeria monocytogenes was identified in a sample and was isolated from a bulk milk tank in the same ACF. With regard to adobera cheeses, all samples were positive for AMB, TC, FC, yeasts and moulds and S. aureus. E. coli was isolated from 28 samples. Salmonella was isolated from a sample and also from a wooden shovel used in the manufacture of the cheeses in the same ACF. Thus, the consumption of unpasteurized fresh cheese may represent a public health risk. Because of this, health authorities should enforce the legislation that forbids the processing of cheese with unpasteurized milk and encourage producers to follow good manufacturing practices from original ingredients all the way through the production process of the cheese to its sale, in order to assure a safe product.

Microbiological Standards for Cheese: Survey and Viewpoint of the Canadian Health Protection Branch

1977 ◽  
Vol 40 (6) ◽  
pp. 411-414 ◽  
Author(s):  
D. L. COLLINS-THOMPSON ◽  
I. E. ERDMAN ◽  
M. E. MILLING ◽  
D. M. BURGENER ◽  
U. T. PURVIS ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Health Protection ◽  
Fecal Coliforms ◽  
International Commission ◽  
Normal Variation ◽  
Total Coliforms ◽  
Unpasteurized Milk ◽  
Heat Treated ◽  
Canadian Health ◽  
And Staphylococcus Aureus

The Health Protection Branch, Health and Welfare Canada is considering proposals for microbiological standards for cheese. These proposals are based on a 2-year study (1974–1976) carried out by the Branch. The proposed standards per gram are: total coliforms m = 500, M = 1500, fecal coliforms m = 100, M = 500, and Staphylococcus aureus m = 100, M = 1000, for cheeses made from pasteurized milk; total coliforms m = 5000, M = 50,000, fecal coliforms m = 500, M = 1000, and S. aureus m = 1,000, M = 10,000 for cheeses made from heat treated or unpasteurized milk. The type of standard proposed will be based on a three-class acceptance plan as developed by the International Commission on Microbiological Specifications for Foods. Use of this plan in interpretation of the analytical results allows for the normal variation between analytical samples.

scholarly journals The prevalence of Listeria monocytogenes and Staphylococcus aureus and their virulence genes in bulk tank milk in Kosovo

2017 ◽  
Vol 11 (03) ◽  
pp. 247-254 ◽  
Author(s):  
Ibrahim Mehmeti ◽  
Hysen Bytyqi ◽  
Skender Muji ◽  
Ingolf F Nes ◽  
Dzung B Diep
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Virulence Genes ◽  
Microbiological Quality ◽  
Bulk Tank Milk ◽  
Bulk Tank ◽  
Quality Of Milk ◽  
And Staphylococcus Aureus

Introduction: Milk is considered to be a healthy, nutritious food product. Microbiological quality is an important aspect in evaluating the quality of milk. Methodology: A total of 603 bulk tank milk samples from 221 farms distributed across ten different regions were collected for milk quality assessment. Quality was judged by total viable count, and the prevalence of two foodborne pathogens (Listeria monocytogenes and Staphylococcus aureus) by using selective media and 16S rRNA gene sequencing. The presence of virulence genes was detected by polymerase chain reaction (PCR) using specific primers. Results: Milk from only 7% (15/221) of farms were found to comply with the European Union standard. Interestingly, the microbiological quality of milk from the larger herd size farms (more than 10 cows) was better than in smaller herds. L. monocytogenes was found in 2.7% (6/221) of farms, and all the examined L. monocytogenes isolates were positive with respect to the virulence genes prfA, actA, and hlyA. S. aureus was found in 39.8% (88/221) of the farms. In total, 30.7% (27/88) of the staphylococci were positive for enterotoxin production. The enterotoxins identified were toxin B (40.7%), toxin D (33.4%), toxin C (18.5%), and toxin A (7.4%). Conclusions: The total number of bacteria in milk was very high. The presence of two foodborne pathogens in raw milk represents a great health risk to consumers. To improve the microbial quality of milk in Kosovo, important measures to improve hygiene, including better information, guidance, and control, are needed.

Microbiological Quality of Fresh Blue Crabmeat, Clams and Oysters

1983 ◽  
Vol 46 (11) ◽  
pp. 978-981 ◽  
Author(s):  
B. A. WENTZ ◽  
A. P. DURAN ◽  
A. SWARTZENTRUBER ◽  
A. H. SCHWAB ◽  
R. B. READ
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Microbiological Quality ◽  
Fecal Coliforms ◽  
Geometric Means ◽  
Colony Forming Units ◽  
Plate Counts ◽  
The Mean ◽  
Eastern Oysters

The microbiological quality of fresh blue crabmeat, soft- and hardshell clams and shucked Eastern oysters was determined at the retail (crabmeat, oysters) and wholesale (clams) levels. Geometric means of aerobic plate counts incubated at 35°C were: blue crabmeat 140,000 colony-forming units (CFU)/g, hardshell clams, 950 CFU/g, softshell clams 680 CFU/g and shucked Eastern oysters 390,000 CFU/g. Coliform geometric means ranged from 3,6/100 g for hardshell clams to 21/g for blue crabmeat. Means for fecal coliforms or Escherichia coli ranged from <3/100 g for clams to 27/100 g for oysters, The mean Staphylococcus aureus count in blue crabmeat was 10/g.

A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods1

1988 ◽  
Vol 51 (1) ◽  
pp. 53-55 ◽  
Author(s):  
F. A. KHAYAT ◽  
J. C. BRUHN ◽  
G. H. RICHARDSON
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Correlation Coefficient ◽  
Cheddar Cheese ◽  
Plate Count ◽  
Impedance Method ◽  
Colony Forming Units ◽  
Fresh Cheese ◽  
Cheese Products ◽  
And Staphylococcus Aureus

A total of 256 cheese samples were analyzed for coliform plate count using violet red bile agar and for an impedance count using BactometerR Coliform Medium with a correlation coefficient between methods of R=−.91. Fifty-four percent of the samples contained 102 to 107 colony forming units/gram (CFU/g). The highest counts were in cream and fresh cheese products. When 27 Cheddar cheese samples were inoculated with from 102 to 107 CFU of Escherichia coli/g a correlation of R=−.97 was found between methods. Two hundred of the cheese samples were analyzed for Staphylococcus aureus using Baird-Parker medium and impedance count using BactometerR S.aureus Medium. Five samples (2%) contained over 103 CFU/g. The strains isolated were coagulase-positive. When 34 samples of cheese were inoculated with 102 to 107 CFU of staphylococci/g, the correlation between the plate and impedance method was R=0.98.

Comparison of Four Commercial DNA Extraction Kits for PCR Detection of Listeria monocytogenes, Salmonella, Escherichia coli O157:H7, and Staphylococcus aureus in Fresh, Minimally Processed Vegetables

2008 ◽  
Vol 71 (10) ◽  
pp. 2110-2114 ◽  
Author(s):  
P. ELIZAQUÍVEL ◽  
R. AZNAR
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Dna Extraction ◽  
Pcr Detection ◽  
Escherichia Coli O157 ◽  
Minimally Processed ◽  
Green Pepper ◽  
Minimally Processed Vegetables ◽  
And Staphylococcus Aureus

Four commercial DNA extraction methods, PrepMan Ultra (Applied Biosystems), InstaGene Matrix (BioRad), DNeasy Tissue kit (Qiagen), and UltraClean (MoBio), were tested for PCR detection of Listeria monocytogenes, Escherichia coli O157: H7, Salmonella, and Staphylococcus aureus in fresh, minimally processed vegetables. For comparative purposes, sensitivity assays with specific PCRs were carried out after DNA extraction with the four methods in green pepper, broccoli, and onion artificially inoculated with the four pathogens separately. As confirmed by statistical analysis, the DNeasy Tissue kit rendered the highest sensitivity values in the three matrices assayed for Salmonella, L. monocytogenes, and E. coli O157:H7 and in onion for S. aureus. Despite being the most expensive of the methods compared, the DNeasy Tissue Kit can be successfully applied for any of the four most commonly studied pathogens, thus saving time and overall reducing the cost of the analysis.

Viability Loss of Salmonella Species, Staphylococcus aureus, and Listeria monocytogenes in Complex Foods Heated by Microwave Energy

1996 ◽  
Vol 59 (8) ◽  
pp. 813-818 ◽  
Author(s):  
RONALD A. HEDDLESON ◽  
STEPHANIE DOORES ◽  
RAMASWAMY C. ANANTHESWARAN ◽  
GERALD D. KUHN
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Chemical Composition ◽  
Food Systems ◽  
Sodium Content ◽  
Salmonella Spp ◽  
Uht Milk ◽  
Mixed Mean ◽  
Liquid Whole Egg ◽  
And Staphylococcus Aureus

The chemical composition of five foods (UHT milk, beef broth, pudding, cream sauce, and liquid whole egg) was examined to determine factors important in achieving uniform temperatures within foods heated in a 700 W microwave oven. Proximate analyses were performed on all food systems to relate their chemical composition to temperatures and to destruction of microwave-heated Salmonella species, Listeria monocytogenes Scott A and V7 and Staphylococcus aureus ATCC 25923. Microwave heating times were chosen such that the final mixed mean temperature achieved by systems was 60°C for Salmonella spp. and L. monocytogenes, and 65°C for S. aureus. The amount of destruction of Salmonella spp. varied from 3.17 log CFU/ml in UHT milk to 0.44 log CFU/ml in beef broth. L. monocytogenes strains incurred the greatest amount of destruction in pudding (2.39 log CFU/g), while the least amount of destruction was observed in cream sauce (1.63 log CFU/ml). There were no significant differences in the amount of destruction of S. aureus heated in the five foods. The pH and aw of these foods did not affect survival of thermally stressed Salmonella, L. monocytogenes, or S. aureus cells. Of the food components examined, sodium content was the primary influence on the uniformity of temperatures achieved within foods, and, in turn, on the survival of bacteria.

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