Bactericidal and Bacteriolytic Effects of Selected Food-Grade Phosphates, Using Staphylococcus aureus as a Model System.

Phosphates have been approved for use in meat products primarily to protect flavor and increase yields. It also is known that phosphates have antimicrobial properties. The objective of this study was to compare the effects of different phosphates in a model system.

Antibacterial Mechanism of Long-Chain Polyphosphates in Staphylococcus aureus.

The results of previous studies indicated that the antibacterial effects of long-chain polyphosphates (sodium polyphosphate glassy [SPG] and sodium ultraphosphate [UP]) to Staphylococcus aureus ISP40 8325 could be attributed to damage to the cell envelope (cell wall or cell membrane). Also, Ca (0.01 M) or Mg (0.

Metal Ions Reverse the Inhibitory Effects of Selected Food-Grade Phosphates in Staphylococcus aureus.

Previous studies showed that levels as low as 0.1% sodium ultraphosphate (UP), 0.1% sodium polyphosphate glassy (SPG) and 0.

Antibiotic Resistance Among Enterococcal Isolates from Environmental and Clinical Sources.

Antibiotic resistance among enterococci and fecal streptococci was examined by testing 149 isolates from pork, water, and clinical material, as well as 50 strains of 13 known species, for resistance to 27 different antimicrobial agents. Tests were performed by using the MicroScan Pos MIC type 6 panels. Pork isolates exhibited less resistance than either water or clinical isolates to most antibiotics, although a larger proportion of pork isolates than others was resistant to tetracycline.

Enterococci in Pork Processing.

The purpose of this study was to determine the numbers and species of enterococci encountered on pork carcasses during different stages in the slaughter process as well as on pork products. Three hog slaughtering plants were surveyed, each 3 times at four processing points. Each hog was swabbed at two sites on the carcass.

Inexpensive, Disposable Presence-Absence Test for Coliforms and Escherichia coli in Water.

Six-ounce (151-g) Whirl-Pak® bags containing 3.05 g of dehydrated Presence-Absence (P-A) Broth and 5 mg of 4-methylumbelliferyl-β-D-glucuronide (MUG) were pasteurized with 10 kGy of gamma irradiation. To conduct a "bag" P-A test, 100 ml of water sample were added to a bag.

Optimal Pyruvate Concentration for the Recovery of Conforms from Food and Water.

Recoveries of coliforms in water and food samples were increased by adding sodium pyruvate to the Tryptic Soy Agar (TSA) base layer, and Violet Red Bile (VRBA) overlay, of the Modified VRBA procedure described in Standard Methods for the Examination of Dairy Products. Six pyruvate levels (0, 0.005, 0.

Aerobic Plate Counts of 100-ml Samples in Plastic Bags .

Counts from samples that contained low numbers of bacteria were determined by mixing the samples with double-strength agar media in 42-oz (1.2-L) Whirl-Pak bags. The bag-plate method was compared with other direct-plating methods and the most-probable-number and membrane-filtration procedures.

Highly Sensitive Paper-Disc Assays for Detecting Penicillin in Milk.

A modified Bacillus subtilis disc-plate assay could detect 0.015 I.U.

Automation for Rapid Identification of Salmonellae in Foods .

Salmonella isolation and identification follow an inseparable continuum of steps from beginning to end. This paper, therefore, encompasses both aspects of the problem. The importance of recovering injured cells is mentioned, and problems in automating the isolation process are described.

The Most Suitable Number of Colonies on Plates for Counting .

Major events that led to acceptance of 30 to 300 as the most suitable number of colonies on plates for counting were reviewed. Three new sets of data were collected, involving triplicate plates of fifteen 1: 1.4 serial dilutions of 65 samples of raw milk.

Modification of Conventional Methods for Recovery of Injured Coliforms and Salmonellae .

This is a review that concentrates primarily on recent developments in the modification of conventional methods for recovery of injured coliforms and salmonellae; 43 of the 58 references were published in 1975 or later. The review encompasses four areas of activity: (a) most probable numbers procedures, (b) membrane filter procedures, (c) direct plating methods, and (d) the influence of other variables.