Most Probable Number Method for Isolation and Enumeration of Staphylococcus aureus in Foods: Collaborative Study

1987 ◽  
Vol 70 (1) ◽  
pp. 35-38 ◽  
Author(s):  
Gayle A Lancette ◽  
John Lanier
Keyword(s):  
Staphylococcus Aureus ◽  
Collaborative Study ◽  
Most Probable Number ◽  
Sodium Pyruvate ◽  
Probable Number ◽  
Milk Samples

Abstract Enumeration of Staphylococcus aureus in foods was collaboratively studied by comparing the present AOAC final action method, 46.062, which uses trypticase soy broth with 10% NaCl to a proposed replacment method which uses the same broth with 1% sodium pyruvate added. Fifteen collaborators analyzed uninoculated samples of milk, tuna salad, and ground turkey, as well as samples inoculated with low (102 cells/g), middle (104 cells/g), and high (106 cells/g) levels of S. aureus. The samples were frozen immediately to maintain the inoculated level of S. aureus in the food. A different strain of S. aureus was used for each food; heat-stressed S. aureus cells were used to inoculate the milk samples. The pyruvate-amended broth significantly (α = 0.05) increased enumeration of low, middle, and high levels of S. aureus from milk and ground turkey, and from tuna salad at middle and high levels. The pyruvate-amended media method has been adopted official first action to replace method 46.062

Current Resuscitation Methods for Recovery of Stressed Staphylococcus aureus Cells from Foods

1986 ◽  
Vol 49 (6) ◽  
pp. 477-481 ◽  
Author(s):  
GAYLE A. LANCETTE
Keyword(s):  
Staphylococcus Aureus ◽  
Egg Yolk ◽  
Single Step ◽  
Most Probable Number ◽  
Sodium Pyruvate ◽  
Probable Number ◽  
Direct Plating ◽  
Selective Agar

Methods and media used to recover stressed and unstressed Staphylococcus aureus cells from foods are reviewed. Most probable number methods using Trypticase soy broth with 10% salt and 1% sodium pyruvate, a liquid modification of Baird-Parker agar and Giolitti and Cantoni's broth with Tween are discussed. Direct plating media reviewed are Baird-Parker agar, modified Vogel and Johnson agar, egg yolk-free Baird-Parker agar and single-step Staphylococcus selective agar.

Enumeration of sublethally heated staphylococci in some dried foods

1976 ◽  
Vol 22 (5) ◽  
pp. 677-683 ◽  
Author(s):  
Andre Hurst ◽  
G. S. Hendry ◽  
Ashton Hughes ◽  
Beverly Paley
Keyword(s):  
Staphylococcus Aureus ◽  
Salt Tolerance ◽  
Adenosine Triphosphate ◽  
Yeast Extract ◽  
Skim Milk ◽  
Most Probable Number ◽  
Acetyl Phosphate ◽  
Sodium Pyruvate ◽  
Probable Number ◽  
Heat Injury

The effect of 45 substances to restore the salt tolerance of sublethally heat-injured Staphylococcus aureus was tested. Sodium pyruvate, yeast extract, L-histidine, casitone (Difco), adenosine triphosphate, and acetyl phosphate were effective. For enumeration a repair medium was first used, containing sodium pyruvate and penicillin in 1% skim milk. This step was followed by counting on Baird-Parker agar with penicillinase. This method was selective; fewer than 100 staphylococci/g food could be enumerated and it gave counts about 8 times higher than the method of Giolitti and Cantoni used as a five-tube most probable number technique. Heat injury sensitized S. aureus to polymyxin.

Occurrence and Characterization of Aeromonas Species in Pasteurized Milk and White Cheese in Rio De Janeiro, Brazil

1993 ◽  
Vol 56 (1) ◽  
pp. 62-65 ◽  
Author(s):  
ANGELA CÔRREA FREITAS ◽  
MARLY PAIVA NUNES ◽  
ARLETE MOREIRA MILHOMEM ◽  
ILVAN DELGADO RICCIARDI
Keyword(s):  
Rio De Janeiro ◽  
Foodborne Pathogen ◽  
Food Samples ◽  
High Rate ◽  
Most Probable Number ◽  
Aeromonas Species ◽  
Probable Number ◽  
Pasteurized Milk ◽  
Milk Samples ◽  
White Cheese

A total of 35 samples (1000 ml each) of pasteurized milk and 25 samples (100 g each) of white cheese purchased at supermarkets in Rio de Janeiro were analyzed for the presence of Aeromonas. Strains of Aeromonas were isolated from 28.5% of pasteurized milk and 32% of white cheese samples. Standard Plate counts in the pasteurized milk samples ranged from 7.2 × 10* to 2.5 × 105 CFU/ml. Total and fecal coliform counts in white cheese samples ranged from 1.9 × 10* to 2.4 × 105 most probable number per g and 3.2 × 102 to 1.2 × 105 most probable number per g, respectively. It was possible to identify Aeromonas caviae (58.9%), Aeromonas hydrophila (12.8%), and Aeromonas schubertii (2.5%) among the cultures isolated from pasteurized milk samples. Twenty-five percent of the strains could only be classified as Aeromonas spp. In white cheese samples, unclassified strains were the most frequent isolates (61.5%) followed by A. hydrophila (26.9%), A. caviae (7.6%) and Aeromonas sobria (3.8%). Only strains of A. hydrophila and A. sobria showed high rate of positive results when tested for the production of hemolysin, cytotoxin, and staphylolytic activity. Heat-stable enterotoxin and autoagglutination test did not correlate as virulence factors. The presence of Aeromonas species in refrigerated food samples suggests that this microorganism could be a potential foodborne pathogen, and dairy products may represent an important vehicle of its transmission.

Detection of Salmonella in Onion and Garlic Powders: Collaborative Study

1979 ◽  
Vol 62 (3) ◽  
pp. 499-502
Author(s):  
Wallace H Andrews ◽  
Dean Wagner ◽  
Mary Jo Roetting
Keyword(s):  
Relative Efficiency ◽  
Collaborative Study ◽  
Most Probable Number ◽  
Rapid Decline ◽  
Improved Method ◽  
Probable Number ◽  
Garlic Powder

Abstract The relative efficiency of trypticase soy broth with added 0.5% K2SO3 and lactose broth as pre-enrichment media for recovering Salmonella from onion powder and garlic powder was collaboratively studied. For each spice, 13 collaborators each received 5 duplicate samples; 4 of the 5 replicate samples were inoculated with 1 of 4 levels of S. thompson ranging, at initiation of analysis, from <3 to 93 organisms/g onion powder and <3 to 43 organisms/g garlic powder. Salmonella growth was inhibited in each of these spices as evidenced by a rapid decline of most probable number values in samples determined immediately after and 7 days following inoculation. Collaborative results of cultural analyses demonstrated superiority of the modified trypticase soy broth for recovering Salmonella in each of the 2 spices. The improved method of detecting Salmonella in onion and garlic powders has been adopted as official first action.

Iron Milk Medium Method for Recovering Clostridium perfringens from Shellfish: Collaborative Study

1994 ◽  
Vol 77 (2) ◽  
pp. 351-356 ◽  
Author(s):  
Carlos Abeyta ◽  
June H Wetherington
Keyword(s):  
Clostridium Perfringens ◽  
Collaborative Study ◽  
Most Probable Number ◽  
Official Method ◽  
Inoculum Level ◽  
Probable Number ◽  
Colony Forming Units ◽  
Aoac Official ◽  
Negative Controls ◽  
Medium Method

Abstract Eleven laboratories participated in a collaborative study analyzing shellfish (oysters, Crassostrea gigas) for the detection and enumeration of Clostridium perfringens by the iron milk medium (IMM) method. The IMM method was compared to AOAC Official Method 976.30. Shellfish were artificially inoculated with C. perfringens cells (vegetative and spores) at low (1 × 103 colony forming units [cfu]/g), medium (1 × 104 cfu/g), and high (1 × 106 cfu/g) levels. Negative controls (zero level) were analyzed by each laboratory. C. perfringens FD-1, the strain involved in a foodborne illness, was used. Blind duplicates of each inoculum level were analyzed, giving a total of 16 samples per laboratory. The selectivity of IMM relies solely on the rapid growth of C. perfringens at 45°C indicated by stormy fermentation reaction within 18 h. C. perfringens is detected and enumerated using the most probable number technique. A statistical evaluation of the data found no significant differences between the estimates from the 2 methods. The IMM method for detection of C. perfringens from shellfish has been adopted first action by AOAC INTERNATIONAL.

Dry Rehydratable Film for Enumeration of Total Coliforms and Escherichia coli in Foods: Collaborative Study

1991 ◽  
Vol 74 (4) ◽  
pp. 635-648 ◽  
Author(s):  
Michael S Curiale ◽  
Therese Sons ◽  
Dawn Mclver ◽  
J Sue McAllister ◽  
Barbara Halsey ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Collaborative Study ◽  
Most Probable Number ◽  
Probable Number ◽  
Total Coliforms ◽  
Repeatability And Reproducibility ◽  
The Mean ◽  
Better Than ◽  
Dry Film

Abstract Rehydratable dry-film plating methods for total coliforms and Escherichia coll In foods have been compared to the AOAC most probable number methods. Fourteen laboratories participated In the collaborative study. Three coliform and £. coll levels In 6 samples of 4 product types (flour, nuts, cheese, and beef with gravy) and in 3 samples of 2 product types (mushrooms and raw turkey) were tested In duplicate by the participants. The mean log counts for the 3 methods were comparable. In general, the repeatability and reproducibility variances of the plating methods were as good as or better than that of the MPN method. The method has been adopted official first action by AOAC.

Precision Parameters for the FDA Shellfish Laboratory Quality Assurance Program for 1973–1989

1995 ◽  
Vol 58 (6) ◽  
pp. 648-650
Author(s):  
JAMES T. PEELER ◽  
THOMAS E. GRAHAM ◽  
LARRY J. MATURIN
Keyword(s):  
Staphylococcus Aureus ◽  
Quality Assurance ◽  
Fecal Coliform ◽  
Quality Assurance Program ◽  
Plate Count ◽  
Most Probable Number ◽  
Probable Number ◽  
Standard Plate Count ◽  
Standard Plate ◽  
The U.S

Precision parameters from four microbiological analytical methods (coliform most probable number [MPN], fecal coliform MPN, Staphylococcus aureus plate count and standard plate count) were computed for the Shellfish Quality Assurance Program of the U.S. Food and Drug Administration (FDA). The pooled reproducibility variance (SR2) for the four methods from 1973 to 1989 were 0.0778, 0.1181, 0.0137, and 0.0087, respectively.

ICMSF Methods Studies. XI. Collaborative/Comparative Studies on Determination of Coliforms Using the Most Probable Number Procedure1

1979 ◽  
Vol 42 (8) ◽  
pp. 638-644 ◽  
Author(s):  
J. H. SILLIKER ◽  
D. A. GABIS ◽  
A. MAY
Keyword(s):  
Comparative Studies ◽  
Confidence Limit ◽  
Collaborative Study ◽  
The Other ◽  
Most Probable Number ◽  
Probable Number ◽  
Collaborative Studies ◽  
Different Types ◽  
Confirmatory Tests

Results of two international collaborative studies on the MPN technique for determination of coliforms in foods are reported. Three methods involving use of different presumptive and confirmatory media were compared. Results of one collaborative study conducted among 15 laboratories using eight different types of inoculated foods showed differences among the laboratories as great as 3.3 log units. The greatest difference between confirmatory tests using different media was 0.5 log units. Results of the other collaborative study conducted among five laboratories using three types of naturally contaminated foods showed differences among the laboratories as great as 1.4 log units. The greatest difference between tests using different media was 0.2 log unit. Both studies showed that the 95% confidence limit for a single value reported by a given laboratory was ± 1 log unit or ± 0.45 log unit for a mean of five values. The second study showed that a major source of variation within laboratories was between replicate aliquots. The findings are discussed in terms of their significance with respect to the monitoring of microbiological specifications for food.

scholarly journals Individual Predisposition to Staphylococcus aureus Colonization in Pigs on the Basis of Quantification, Carriage Dynamics, and Serological Profiles

2014 ◽  
Vol 81 (4) ◽  
pp. 1251-1256 ◽  
Author(s):  
Carmen Espinosa-Gongora ◽  
Jan Dahl ◽  
Anders Elvstrøm ◽  
Willem J. van Wamel ◽  
Luca Guardabassi
Keyword(s):  
Staphylococcus Aureus ◽  
Humoral Response ◽  
Nasal Carriage ◽  
Most Probable Number ◽  
Cross Sectional ◽  
Probable Number ◽  
Content Type ◽  
Luminex Assay ◽  
Nasal Swabs ◽  
Cross Sectional Design

ABSTRACTPrevious research onStaphylococcus aureusin pigs focused on livestock-associated methicillin-resistantS. aureus(MRSA) and had a qualitative cross-sectional design. This study aimed to elucidate the frequency, load, and stability ofS. aureusnasal carriage in pigs over time and investigated possible associations between carriage and immune response. Nasal swabs were collected three times weekly from 480 tagged adult pigs in 20 Danish production farms.S. aureusand MRSA were quantified on selective media by the most-probable-number method. The levels of IgG against 10S. aureusantigens in serum were quantified in selected pigs by a Luminex assay. All the farms were positive forS. aureusand 15 for MRSA, leading to overall prevalences of persistent and intermittent carriers and noncarriers of 24, 52, and 23%, respectively. Carriage frequency and nasal loads were significantly higher on MRSA-positive farms. Logistic-regression modeling revealed the presence of individual pigs characterized by high nasal loads (≥10,000 CFU per swab) and stable carriage regardless of farm- and pen-associated factors. On the other hand, the humoral response was strongly influenced by these environmental factors. The existence of a minority of shedders contributing to maintenance ofS. aureuswithin farms opens up new perspectives on the control of MRSA in pig farming.

scholarly journals Microbiological evaluation of South Australian rock lobster meat

1977 ◽  
Vol 79 (3) ◽  
pp. 373-380 ◽  
Author(s):  
A. S. J. Yap
Keyword(s):  
Staphylococcus Aureus ◽  
Geometric Mean ◽  
Plate Count ◽  
Most Probable Number ◽  
Rock Lobster ◽  
Probable Number ◽  
E Coli ◽  
Processing Plants ◽  
Australian Fish

SUMMARYSamples of frozen precooked rock lobster meat from five South Australian fish-processing plants situated in the West Coast and south-east regions were tested over a period of six months during the 1974/5 lobster fishing season. The most probable number (MPN) ofE. coliand coliforms,Staphylococcus aureusandSalmonella, as well as total plate count (TPC) were determined in 480 samples. Monthly geometric mean TPC ranged from 1600/g to 25,000/g. The highest geometric mean of the MPN of coliforms andE. coliwere 4·9/g and 1·8/g respectively. The highest geometric mean number of staphylococci was 18·6/g.Salmonellawas not detected in the 480 units tested. Only 0·4% of the samples had TPC exceeding 100,000/g. Coliforms andE. coliwere not present in 76·1% and 92·7% respectively of the samples tested.Staphylococcus aureuswas not detected in 67·7% of the samples. The numbers of organisms in 82% of the samples fall within the microbiological standards proposed by the National Health and Medical Research Council of Australia for frozen precooked foods. The results of this study demonstrate the microbial quality of precooked lobster meat attainable when good manufacturing practices are used.

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