- Assessment of Baird-Parker Agar as Screening Test for Determination of Staphylococcus aureus in Poultry Meat
-
Rosa Capita , Carlos Alonso-Calleja , Benito Moreno , Maria del Camino Garcia-Fernandez
-
J. Microbiol. 2001;39(4):321-325.
-
-
-
 Abstract
 PDF
-
Baird-Parker agar with egg yolk/tellurite emulsion (BPA) is widely accepted as a medium for the enumeration of Staphylococcus aureus in foods. However, it is not completely selective and colonies of other genera or species could be similar to those of Staphylococcus aureus. Moreover, the strains of Staphylococcus aureus that are lecithinase negative could go unnoticed. Both facts could affect the counts. The aim of this study was to determine whether the enumeration of the colonies with the typical morphology of Staphylococcus aureus on BPA is sufficient to quantify this species in poultry meat. Forty chicken carcasses were tested for Staphylococcus aureus by surface plating using BPA. Results indicate that the predictive value of the morphology of the colonies on BPA is 85.71% and 68.42% for typical and atypical colonies of Staphylococcus aureus, respectively. However, Staphylococcus aureus counts (after identification) and counts of typical colonies did not show any significant differences (P>0.05) and are significantly (P<0.001) correlated (r = 0.996). These results suggest that, for screening purposes, enumeration of Staphylococcus aureus from poultry meat does not require any identification of strains, resulting in a saving of time and money.
- Evaluation of the EF-18 Agar-Hydrophobic Grid Membrane Filter (HGMF) Method to Isolate Salmonella from Poultry Products
-
Rosa Capita , Maite Alvarez-Astorga , Carlos Alonso-Calleja , Maria del Camino , Garcia-Fernandez , Benito Moreno
-
J. Microbiol. 2001;39(3):202-205.
-
-
-
Abstract
PDF
-
The EF-18 agar/hydrophobic grid membrane filter (EF18/HGMF) method was evaluated for the isolation of Salmonella in naturally contaminated chicken carcasses, chicken parts (legs, wings and giblets) and processed chicken products (sausages and hamburgers). Percentages of false positive results for Salmonella (colonies with a similar morphology to those of Salmonella) were 78.75, 81.67 and 80% for carcasses, chicken parts and processed chicken products, respectively. The bacterial isolates that caused false positive reactions using this method were identified as Proteus mirabilis (70.85%), Citrobacter freundii (15.25%), Klebsiella ozaenae (5.83%), Hafnia alvei (4.48%), Escherichia coli (2.69%) and Enterobacter aerogenes (0.90%). The data obtained in this study suggest that the EF-18/HGMF method is not sufficiently selective or specific for isolating Salmonella from meat and chicken products.
- Phage Typing of Staphylococcus aureus Isolates from Poultry Meat in Spain
-
Rosa Capita , Maite Alvarez-Astorga , Carlos Alonso-Calleja , Benito Moreno , Maria del Camino Garcia-Fernandez
-
J. Microbiol. 2001;39(3):219-225.
-
-
-
Abstract
PDF
-
Phage typing is currently used for typing of Staphylococcus aureus strains beyond the species level in epidemiological studies. A total of 168 Staphylococcus aureus isolates from chicken meat and chicken by-products were phage-typed using the international bacteriophage set for typing Staphylococcus aureus of human origin. One hundred and forty-eight (88.09%) strains were phage-typeable (at least one phage produced 20 or more plaques of lysis). Lysis by phages of group III was the most frequent with 99 (58.93%) sensitive strains. This fact coincides with results of other authors. Twenty-nine different phage patterns were observed and three (95, 75/84 and 6/1030/W57) were most common. One hundred and thirty-two (89.19% of typeable strains) showed these or indistinguishable (only one phage reaction difference) patterns. Twenty-six out of seventy chicken samples (37.14%) harboured more than one phage type of Staphylococcus aureus. This fact emphasizes the convenience of subtyping several Staphylococcus aureus isolates from the same sample in epidemiological studies. 80% of sausages and hamburgers contained the same Staphylococcus aureus phage types, which were not found in any of the other food types. This fact suggests a cross contamination during the processing of these foods. Phages 6, 75, 84, 1030 and W57 showed the greatest activity. None of the Staphylococcus aureus strains were sensitive to phages 47, 81 and 94.
|
MSK
