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

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.

1987 ◽  
Vol 70 (1) ◽  
pp. 35-38 ◽  
Author(s):  
Gayle A Lancette ◽  
John Lanier

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


1986 ◽  
Vol 49 (6) ◽  
pp. 477-481 ◽  
Author(s):  
GAYLE A. LANCETTE

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.


1991 ◽  
Vol 54 (7) ◽  
pp. 532-536 ◽  
Author(s):  
GERALDINE M. FARRELL ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH

Autoclaved whole milk, low-fat milk, protein-fortified skim milk and regular skim milk were inoculated to contain ca. 105 to 106 Borrelia burgdorferi strains 35210, 35211, or EBNI/ml and stored at 34°C for 16 d. Similarly inoculated skim milk also was held at 5°C for 46 d. Numbers of survivors were estimated by the Most Probable Number (MPN) technique. In all instances, numbers of B. burgdorferi decreased over the storage period. At 34°C, no strain of B. burgdorferi was detected after day 12. The mean D-values, at 34°C, for strains 35210, 35211, and EBNI were 2.2, 2.4, and 2.2 d, respectively. The mean D-values, at 34°C, for all strains in whole milk, low-fat milk, protein-fortified skim milk, and regular skim milk were 2.4, 2.3, 1.9, and 2.4 d, respectively. At 5°C, spirochete numbers in regular skim milk decreased, but all three strains remained at a detectable level for 46 d. The mean D-values, at 5°C, for strains 35210, 35211, and EBNI were 12, 15, and 12 d, respectively.


1995 ◽  
Vol 58 (6) ◽  
pp. 648-650
Author(s):  
JAMES T. PEELER ◽  
THOMAS E. GRAHAM ◽  
LARRY J. MATURIN

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.


2006 ◽  
Vol 69 (1) ◽  
pp. 217-220 ◽  
Author(s):  
RITA CAVA ◽  
ELBA SANGRONIS ◽  
FULGENCIO MARIN-INIESTA

Alkaline peptone water (1% peptone, 1% NaCl, pH 8.5) and Trypticase soy yeast extract broth (TSYB) supplemented with 2.5% NaCl (pH 8.5) or 1% NaCl (pH 7.5) were evaluated as enrichment broths for the isolation of Vibrio cholerae O1 from ice. Thirty samples of sterile and nonsterile mineral water were inoculated with cell suspensions of this bacterium, quickly frozen, and stored for 3 days at −18°C. After thawing, samples were analyzed by a three-tube most-probable-number technique. Incubation in TSYB with 2.5% NaCl (pH 8.5) for 18 h at 37°C yielded the highest recovery of V. cholerae O1 cells (P < 0.05), a result that might be attributable to the nutrients and to the NaCl concentration of the TSYB, both of which would promote V. cholerae O1 growth and prevent the growth of competitive microbiota.


2014 ◽  
Vol 81 (4) ◽  
pp. 1251-1256 ◽  
Author(s):  
Carmen Espinosa-Gongora ◽  
Jan Dahl ◽  
Anders Elvstrøm ◽  
Willem J. van Wamel ◽  
Luca Guardabassi

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.


1977 ◽  
Vol 79 (3) ◽  
pp. 373-380 ◽  
Author(s):  
A. S. J. Yap

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.


2011 ◽  
Vol 77 (10) ◽  
pp. 3541-3543 ◽  
Author(s):  
Emily Levin-Edens ◽  
John Scott Meschke ◽  
Marilyn C. Roberts

ABSTRACTRecreational beach environments have been recently identified as a potential reservoir for methicillin-resistantStaphylococcus aureus(MRSA); however, accurate quantification methods are needed for the development of risk assessments. This novel most-probable-number approach for MRSA quantification offers improved sensitivity and specificity by combining broth enrichment with MRSA-specific chromogenic agar.


2016 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
Ratih Dewi Dwiyanti ◽  
Leka Lutpiatina

<p style="text-align: justify;">Abstract: The food was used as a complementary flavor sauces include snacks bulb. Dressing materials according to SNI 01-7388-2009 must comply with the requirements of the parameter Staphylococcus aureus, MPN (Most probable number) Coliform, TPC (total plate count) and molds. This study aims to determine the percentage of tomato sauce snacks bulb in the area around the intersection of four Banjarbaru who do not qualify SNI 01-7388-2009 of parameters MPN Coliform and Staphylococcus aureus. The results showed MPN Coliform tomato sauce ranges from 0-240 and Staphylococcus aureus 5 x 101 to 6.5 x 103. Concluded percentage tomato sauce snacks bulb that does not qualify SNI 01-7388-2009 parameter is 60% MPN Coliform and Staphylococcus aureus 80%. Suggestions to determine the value of TPC (total plate count) and molds and other chemical parameters of tomato sauce.


1993 ◽  
Vol 76 (3) ◽  
pp. 632-634 ◽  
Author(s):  
Alain Martin ◽  
Stanley E Katz

Abstract A resuscitation medium consisting of a trypticase soy broth base supplemented with 0.5% yeast extract, 0.25% sodium pyruvate, 0.01 % sodium thiogly col late, and 0.1 % chicken fat was used in the resuscitation of heat-injured and freeze-injured cells of Listeria monocytogenes. After a resuscitation period of 4-h, the medium was made selective through the addition of nalidixic acid, acriflavin, and cycloheximide. The organisms were incubated in the selectivized medium at 35°C for an additional 16 h. The numbers of resuscitated Listeria monocytogenes cells rose from 101 to 107 cells/mL in 20 h. Similar numbers of Staphylococcus aureus, Escherichia coli, and Salmonella bonn were grown together with Listeria monocytogenes; these organisms did not inhibit the growth of Listeria monocytogenes nor interfere with its detection by the Listeria-Tek kit system. The resuscitation/selection/ kit system (RSK) was compared with the methodology in the Bacteriological Analytical Manual (BAM) for the detection of Listeria monocytogenes in 22 naturally contaminated cheese samples: 8 of these were positive by the BAM system and 12 were positive by the RSK system. The 8 Listeria positives found by the BAM system were positive by the RSK system. All 12 Listeria-presumptive positive samples by the RSK system were confirmed to be Listeria monocytogenes. The use of the RSK system enhanced the recovery of the pathogen, and detection was accomplished within 24 h.


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