Rapid detection of staphylococcal thermonuclease on casings of naturally contaminated fermented sausages

Abstract

Staphylococcal food poisoning associated with fermented sausages has been a recurring problem. By testing for thernonuclease by direct application of sausage casing disks on the surface of thermonuclease assay agar plates, possible Staphylococcus aureus growth in fermented sausages could be detected simply and rapidly. Koupal-Deibel deoxyribonucleic acid agar was somewhat superior to toluidine blue deoxyribonucleic acid agar for thermonuclease assay of fermented sausage casings. The sensitivity of the thermonuclease casing test was comparable to that of the extraction procedure, and the thermonuclease casing test results were in complete agreement with the thermonuclease assay results by the extraction procedure. The thermonuclease casing test offers government and industry laboratories a useful screening tool which could significantly reduce the problem of staphylococcal enterotoxins in fermented sausages.

Survival of Escherichia coli O157:H7 in broth and processed salami as influenced by pH, water activity, and temperature and suitability of media for its recovery

“…Preservation of salami is achieved by the synergistic or hurdle effect of salt, sugar, nitrite, nitrate, polyphosphates, reduced water activity (a w ) and pH, low storage temperature, and decreased oxidation-reduction potential achieved by packaging (casings) and/or drying (4). Growth of lactic acid bacteria, which are commonly added to salami formulations, reduces the pH to 4.8 to 5.0, thus inhibiting growth of food-borne pathogens (15,22). The effectiveness of combined factors such as pH, chemical preservatives, refrigeration temperature, and heating in the preservation of cured meat products has already been described (21).…”

Burden of perianalStaphylococcus aureuscolonization in nursing home residents increases transmission to healthcare worker gowns and gloves

“…It is a common molecular target for the rapid detection of S. aureus in blood and food samples and can be used to determine S. aureus colonization status. [11][12][13] In in vitro validation of our q-PCR methods, the number of nuc gene copies isolated from serial dilutions of standard MSSA (ATCC 43300) and MRSA (ATCC 29213) isolates (American Type Culture Collection, Manassas, VA) correlated well across a range of 10 3 -10 7 CFU with the quantitative cultures of these isolates (r = 0.997 and 0.999, respectively).…”

Factors affecting the production of thermonuclease by Staphylococcus aureus Z88

“…2) speed, and 3) no special techniques or equipment are required (Lachica et al, 1971(Lachica et al, , 1972a. The major dis advantage of the assay is the problem of improper color de velopment (Emswiler-Rose et al, 1980;Koupal and Deibel, 1978) which may be due to protein interference (Lachica et al, 1972b).…”

“…The medium was incubated for 3 hours at 37°C; the appearance of bright pink halos indicated nuclease activity. Problems with the assay included the development of greenish halos with some assays and improper pink color development(Emswiler-Rose et al, 1980; Lachica et al, 19 72b). Another direct application method used byEmswiler- Rose et al (1980) involved the use of the casings of contami nated sausages on TB and KD agars.…”